#ash clouds

Walked under a band of candy floss clouds dusted with ash from the weather’s sorrow-lit cigarette, not far, a gutter, a snare drum for the rain beats, and the day marches on. As any child would, we played with paper boats and guided them down the storm drain, and we saw tomorrow unfold before us, who we are and where we are going to be. Our homes walked away where they once stood, and the waves…

Cumbre Vieja - La Palma

02:23 13/10/2021

Fig. 1. One of the kipukas (that is, untouchedby- lava areas of forest).

The abandoned lava cliff at Kalapana

This is a stretch of old cliff face that is now several hundred metres from the sea. It is located among the flows of February 1992 to October 2003, but the area was re-flooded with lava between 2007 and November 2013, when the ocean entry hereabouts was blocked. The site is just under 5km southwest of present-day Kalapana near Poupou, where the Royal Gardens lava flow reached the coast. The walk is well worth the effort for the variety of lava formations, the many tumuli or blisters of lava, and the coastal scenery along the present cliffs. We were guided here by Gary Sleik, who lives on the lava at Kalapana.

Fig. 2. The first section of cliff face, with the lens-shaped tube blocked by cindery flow.

The cliffs are backed up by a small kipuka, which is an area that was left untouched, as the lava flowed around it and therefore is still a lush, well-forested island among the dark bare lava. There are several such fortunate stretches of original forest in the area. The first section of cliff face is a tale of its history – two major flows that came over this area in the distant past, including a lava tube between them, since filled in with an very cindery flow that came though the tube and over the surface. Behind this cliff, there are several windows down into lava tubes, which are mainly blocked up with subsequent flows and one may well lead to this lens-shaped opening. The base of the cliff is now buried by an unknown depth of fresher black pahoehoe lava. The detail of one episode can be seen in one small section, where the lower vesicular flow was several metres thick and formed slightly columnar shrinkage cracks through its depths, but also has a dark ropey lava surface. Above this, there is the clinkery a’a flow at the level of the lens-shaped tube.

Fig. 3. A small section of the cliff face, showing the junction between flows.

On the next section of cliff face, the thick basalt layers are more irregularly broken up and there is a cave entrance at the level of the new flow. This entrance is about half a metre high and little more than a metre wide. Around it, there are slump areas in the new lava, where molten lava was sucked down, perhaps into this cave or others. From the entrance, the cave had a drop of several metres onto fallen blocks and fresh flow. Although it is deep, it is not far across – the opposite wall can be seen with a good torch. It is an a’a flow above a much more columnar basalt face, with its top pediment several metres below the entrance level. Unfortunately, the drop to the floor of the cave is a long way in the dark, especially with no way to climb out. The mass of cobwebs across the entrance doesn’t help, either. However, it is possible to look down to the right and see the next level down in the cave – the floor drops steeply to a lower level, in a lava fall underground. There are interesting dribbles and fingers of lava around the cliff near the cave, such as several openings that contain miniature grottos of stalactites and small pillars of lava. Also, along the edge of the cliff, the remains of the former forest can clearly be seen. Tree moulds are also easily visible in the cliff face, with a complete coconut cast among them.

Fig. 4. The cave entrance, less than a metre high at the base of the cliff.

Moving further along this cliff line, there is a skylight down into a lava tube. Around ten meters deep, the walls seem to be comprised of mainly solid basalt blocks and there are two levels at which the lava flowed for extended periods. The floor and the base of the upper level have pahoehoe surfaces. There is reputedly an extensive network of such tubes in this area, one called the Cave of Refuge, which has a variety of legends attached to its historical uses. It seems that some are several hundred metres long and some are interconnected. Once again, it is difficult to explore without a known way out or the necessary equipment. The columnar nature of the thicker lava is seen in some of the deep cracks in the vicinity.

The cliff then changes entirely in its character. This location was once an ocean entry point, where the lava exited one or more of tubes and flowed over the cliff in a mass of fire-falls. They left innumerable wonderful flows and dribbles in great variety, caught in the act and frozen in a near-vertical face.

Fig. 5. Inside the cave, showing the columnar face opposite the entrance. The flow into the lower level is at lower right, under the columns.

Kapoho Cone and Green Lake Crater

Of course, the whole of Big Island Hawaii is made of lava and this corner of Puna District is no exception. From Kilauea to Kumukahi Cape runs the East Rift Zone, with a parallel graben (down-faulted section). There is thought to be no direct connection between the rift faults and the graben.

Fig. 15. A map of the Kapoho eruption. Cape Kumukahi is the eastern-most point of Hawaii, extended by the a’a and pahoehoe lava floods of 1960.

There have also been several volcanic events in this area. The earliest one that has been dated with any accuracy is from about’ 400 years ago,’ when the Puʻu Kapoho cone formed during a phreatomagmatic (steam-powered) eruption. The hill doesn’t look to be particularly volcanic from the surrounding area, because it lacks the conical height and angle of slope of a true cinder cone (it is only 110m high). This was extremely explosive because of the amount of water present, which is a result of its very low height above sea level. This kind of activity formed a low, broad cone, with abundant fine particles that helped cement the ash and larger fragments and angular blocks together to form a volcanic tuff cone, which soon turned to the reddish brown of iron-rich lavas. Diamond Head, Punchbowl and Koko Head on Oahu are also tuff cones at a low elevation in Hawaii, but are much more famous than Kapoho.

Fig. 16. A view across the a’a field to Kapoho Hill (Pu’u means hill), which erupted sometime in the first half of the seventeenth century, in a series of phreatomagmatic events from four fissures.

It may not appear to be especially volcanic at first, but it has a distinct rim on three sides and it is entered by the gap on the eastern flank, where the lava and pyroclastic materials flowed outwards. The track takes you up to a car park and recreation area. From here, it is possible to see down into the lake and upwards around the rim. Without contemporary accounts, it is not easy to build up a clear picture of the eruption around the 1600 AD, but there were seemingly four active vents erupting explosively, one of which produced the inner crater that began to collect water soon after the eruption ceased. This resulted in Green Lake and the water really is green – with algae. It is known to Hawaiians as Ka Wai a Pele.

Fig. 17. Cross section of reddish tuff deposits blasted out during the very explosive, steam-driven eruption from four fissures. Now covered by more recent lavas.

Opinions differ as to whether this is on private or state land, but there is a gate and an admission charge of five dollars, which goes to local community causes, including the upkeep of the site. While we were visiting, the access from the rim down to the water was said to be closed because of damage caused by Hurricane Iselle, two months earlier. The water had reputedly been polluted by vehicles blown into it during the hurricane, although there was no sign of them or any oil on the surface – just a few damaged trees and forest debris in the lake. It is a very popular picnic spot and recreation ground for local people, and some swimmers were climbing up the path from the water when we arrived. Views down into the lake are restricted by the dense woods that fill the area, but there are glimpses of the lake from the rim.

Fig. 18. An aerial view of the Kapoho tuff cone, with Green Lake almost in the centre and the 1960 flow at bottom right. The almost circular shape of the crater is very clear, with the outflow coming down the middle of the picture.

We had a four-wheel drive rental car and were encouraged by the gate staff to drive to the top rim of the volcano, where there is additional parking and a picnic area. It is about a half-hour walk or five minute drive from the lake overlook. The view from the top is most worthwhile – right across this corner of the island, including all of the eruptive features from earlier and later times. Later eruptions very close by took place in 1840, 1923 (although with no surface lava), in February 1955 and January 1960.

A personal communication from the aerial photographer informs me that he, William Appleton, owns the land and he kindly gave permission to use the picture. He also added that recent thinking suggests that the crater and lake were formed only 350 years ago, rather than the 400 years, as traditionally suggested. There is apparently a proposal to build a geothermal power plant in the vicinity, although current thought is divided about whether the lake water is purely run-off or has a tidal connection (which could contravene groundwater pollution laws).

Tottering on the a’a lava at Kumukahi Lighthouse Point

A real disaster came to the small village of Kapoho, which was a place that lived by growing coffee, papayas and orchids. Early in 1960, there was a major eruption linked to Kilauea, from Puʻu Kapoho. It was one of a series of eruptions from the flank volcanoes of Kilauea. This was the last eruption in this immediate area and centred on a series of fissures just to the north of Kapoho and Green Lake. They are believed to have erupted from the same fissure system as Kapoho and are referred to as the Kapoho eruption, even though they didn’t come out of the actual Kapoho crater, where Green Lake is located. Lava spread eight or nine kilometres across Cape Kumukahi to the sea, extending the coast by an area of two square kilometres during 1960.

Fig. 23. Dominating the town in the early days, the fire fountain produced masses of cinder, as well as lava.

When the summit eruption of Kilauea Iki ceased in December 1959, it was known that the magma chamber was more inflated than it had been at the start of the eruption, so it was no surprise when earthquake rumbles began further along the fault line of the East Rift Zone the following month, with over a thousand recorded on 12 January 1960. Overnight, large cracks opened in the ground in Pahoa and Kapoho towns, both of which are located on the rift line. By 8am, more large cracks opened up and lava fountains began along the main split about 300m from Kapoho, within the graben, rather than along the actual rift line. Within half an hour, lava was spurting up to 30m high, along a fissure of just under a kilometre in length, with flows of pahoehoe and a’a lava flooding away from the fissure. Before long, cinder and spatter cones were being formed as the fountaining increased and started to concentrate in particular points, all about eight kilometres from the sea. The largest of these was Pu’u Laimana, just north of the Kapoho Cone.

There was a period of phreatomagmatic activity, when saltwater from Warm Springs Resort came into contact with the magma, and large quantities of fine black ash were produced by extremely powerful and spectacular outbursts. These clouds and their contents reached as far away as Oahu and even Kauai – a distance of over 535km.

The layers of ash were buried by later lava flows. A huge pahoehoe flow moved smoothly at around 3kph, carrying rafts of crusted lava – known as slag (as in the mining and smelting industries). Later lava fountains were up to 60m high with explosive bursts. A lot of flame was seen from burning ohio trees and methane in buried forest litter. Methane fires erupted from the ground behind photographers, who were then close to the leading edge, forcing speedy retreats. Before long, the rich coffee, orchid and papaya fields were entombed under lava and ash, and a record number of properties were destroyed in one evening (over a hundred). Legally, the fire brigade was obliged to try to stem every single fire, though their hoses were clearly having no effect whatsoever. The town was largely burned out, and then submerged under lava or giant heaps of cinder and ash. Bulldozed ridges and dykes were ignored by the lava, which opened new fissures further west.

Fig. 24. As the lava flowed through Warm Springs Resort, the contact with the underground water source produced powerful steam blasts and clouds reaching thousands of metres into the air.

Activity intensified and the fountains were estimated at 350m for several days, and reaching 450m at times. Vast quantities of lava flowed towards the coast. The mainly pahoehoe flow carried huge slabs of former crust at an estimated 3kph, in enormous amounts over a three-kilometre wide front.

The underside of the slabs is generally either an extremely sharp ‘pluck’ surface, where the near-solid lava has dragged loosely across earlier rock; or a ‘drip’ surface, where the underside has still been molten, but lifted, which allowed the liquid lava to drip downwards into the gap below. Either form is extremely difficult to walk on, when the slabs have been jumbled up and turned over, or left jammed on edge.

Fig. 27. Fast-moving lava flows tumbled over obstructions in lava-falls, carrying large amounts of surface ‘slag’, which are rafts of crust from earlier solidifying areas.

Eventually, the flow began to diminish in power and the great fountains were lessening and sending out ‘soggy bombs’ rather than great heights of spatter, turning red as the temperature dropped and the volume decreased. Within a day or two, the fountaining was finished, but it took another two weeks for all the lava movement to cease. The slowly continuing lava gradually became cooler and the surface was changing into an a’a flow of ‘broken and crumbly’ blocks and cinders, carried along by the slowed-down more fluid lava beneath. This slowly built up to a wall of a’a lava four and a half a metre high, and travelling at less than a half a kilometre an hour across the Kumukahi Cape.

The a’a flow is the one that finally covered most of the area, overrunning the coastguard and lighthouse stations. However, it skirted round the lighthouse itself, leaving it untouched with six metres to spare on three sides. This lava is very broken up a’a, with large and small blocks, and slabs and crust sections. And there, amongst it, stands the open girder-work of the lighthouse – untouched.

Fig. 28. Slab lava being formed from the rafts of crust that were carried along by the still molten lava beneath. My thanks to Darlene Cripps and Gary Sleik for this picture.

The whole surface of the a’a flow is very rough, but stable. The blocks and slabs cooled while still stuck together, as opposed to a mass of loose cindery material, which can be very unstable. If the face of an a’a flow becomes very solidly fixed, it holds back the continuing flow of molten lava behind it. This will cause upward pressure beneath the crusted surface. One way to release the pressure is for the lava to squeeze out between hard slabs and blocks. This can frequently produce an effect like toothpaste being squeezed out of a tube, as the lava exudes onto the surface and is pushed away. The surface flow will often retain the grooved nature of the gap through which it came, making a series of fluted lines along the surface.

Here and there among the tangled masses of a’a blocks and slabs, these flatter areas survive where the ‘toothpaste’ areas of flow have not broken up – presumable among the last active phases of the eruption. Like roadways through the broken jumble, they have longitudinal grooves that reflect the edges of the crack they were forced out of. Some of them also have ‘pressure pulse’ lines across them, which have something of the appearance of a roughly-ploughed field. They indicate that the lava was squeezed out in pulses, perhaps half a metre of forward movement across a nine-metre wide front. They occur at many points throughout the a’a flow, including in the vicinity of the lighthouse, and not just close to the original crater. This implies that the lava travelled a considerable distance under the main surface before it solidified, and then surfaced wherever it was able to force its way upwards.

Similar at first sight to the ‘toothpaste’ roadways are flat runs of lava, which were surface flows of pahoehoe lava, just at the stage where it ran out of strength and heat. However, the pahoehoe flows have curved wrinkles spreading across them and extending back along the edges towards the source of the lava; whereas the toothpaste flows have grooved lines along the length of them, except for the ‘pulse’ lines cutting across the flow, which are usually straight, rather than curved.

Fig. 35. The lighthouse at Cape Kumukahi remained untouched.

Two additional features of this a’a flow are worthy of note. The first is the evidence of the under-surface continuing flows – the numerous lava tubes varying from a foot across to seven metres or so. As the source of lava diminished, so the level within these tubes dropped and left the roof perched above the new tube or cavern. The second feature is the sheer size of some of the slabs of crust. While most are a less than a metre across, broken by continual movement of the lava below, some are huge – as large as a three-storey house, but perhaps less than a metre thick. It is possible that one or two of these may be complete sections of the surface that began to topple into the sea during a cliff collapse (or ‘bench collapse’), when a whole area of the flow was undermined by waves.

Equally interesting for the petrologist or mineralogist is the detailed and varied nature of the rock hereabouts, within six metres of the parking. Some broken blocks reveal very dense, almost bubble-free interiors, probably indicating that hot lava burned out its gaseous content before setting hard. Others are filled with bubbles (vesicles) and are almost as light as pumice. These are sometimes stretched longitudinally in the direction of the flow. It is common here to find blocks containing both kinds of lava, often in layers. In such cases, the bubbles may have acted as a kind of ‘‘oil slick’’ that enabled one layer to slide across the other. It is a common feature of a’a blocks that the whole mass of the flow does not all move at the same speed. These layers of bubbles are one of the mechanisms for the differences in speed.

Three metres beyond the small car park at the lighthouse, many of the rocks contain olivine crystals in abundance. One hand-sized rock displayed more than 20 crystals, but they were only a few millimetres across, with the largest we found being almost a centimetre across. The presence of olivine crystals indicates that the magma originated deep in the Earth’s crust and quite possibly in the upper mantle. They are one of the first minerals to crystallise out of the base rock as it cools, so these indicate a fairly slow cooling process. Olivine – otherwise known as peridot and chrysolite – is magnesium iron silicate, which owes its green colour to the presence of nickel.

Fig. 40. Hot molten lava lurking below the hard crusted surface at the time of the eruption. My thanks again to Darlene Cripps and Gary Sleik for this picture.

The aftermath of the eruption is plain to see. The town and its fields had almost entirely gone in six weeks of eruption. Ten square kilometres were buried under fresh lava and two square kilometres of new land extended into the sea. Around 130 million cubic metres of material were ejected, mostly lava, but also some pyroclastic material. It was the third largest eruption by Kilauea in the last century, after Mauna Ulu from 1969 to 1971 and Pu’u O’o-Kupaianaha from 1983 to the present.

Kapoho was never rebuilt. The area is a desert of a’a blocky and slab lava. Almost all the fields of orchids were ‘rescued’, with the plants being dug up before the lava reached them. One particular type of orchid survived – the bamboo orchid is now one of the most common plants among the lava flows and along the roadsides.

Even our 2014 visits didn’t do justice to this area – a’a lava is just as fascinating as the beauteous pahoehoe type. This lava field is basically a great expanse of shattered blocks and slabs, all tumbled and jumbled together. It is the result of the nature of the lava flow towards the end of an eruption, when the lava was cooling down.

Fig. 44. Some rocks contain great masses of bubbles. This one was very light and was the same structure all the way through.

There is a memoir of the event still available: Kapoho: Memoir of a Modern Pompeii (Paperback) by Frances H. Kakugawa. A professional photographer, Fred Rackle, filmed much of the eruption, and the superb result can be viewed at: https://www.youtube.com/watch?v=2BsIm7iodIs.  There is also further information at the CSAV site of Hilo University http://hilo.hawaii.edu/~csav/.

Visiting Lava Trees State Monument

This is a seven hectare park between Pahoa and Kapoho, on Highway 132. There is free admission in daylight hours, with a circular trail of about a kilometre. The pathway winds among numerous lava trees in a grass parkland and woodland setting that is like a fairy glen in the misty rain. The park is also well known for its living trees and the many different flowering bushes there. What we hadn’t realised was that Hurricane Iselle had torn through Puna District on a August 2014, less than two months before our arrival and this area took the brunt of the strongest tropical cyclone that Hawaii has encountered in recorded history. The Kapoho (132) Road to Lava Trees State Monument had been blocked by hundreds of huge fallen trees. By October, the road had been cleared, but it seems that the modern living trees in the park hadn’t fared as well as the lava-created versions. When we arrived there, the park was still closed, so we didn’t manage to visit in 2014. It was fortunate that we had been on previous occasions, and found other superb examples of lava tree moulds in this district.

Fig. 49. The park is beautifully laid out and manicured.

A flow of tholeiitic basalt (containing less sodium than some other basalts) from Kilauea’s eastern rift zone swept through the ohia forest here in 1790. This was the most devastating eruption in Hawaii’s recorded history, since the one in which at least 80 Hawaiian warriors under Chief Keoua were suffocated by volcanic ash on their way to attack the senior chief, Kamehameha. This forest was drowned to a depth of up to three metres in places and perhaps as much again around a few trees. It is thought that during the eruption, fissures opened up in the area and lava drained into them very rapidly, with the surface level dropping to less than half a metre high within hours of the initial flood. Some of these fissures are still visible around the park and there are notices warning of their hidden risks. It left behind a coating of lava on the standing trees about 15 to 30cm thick and on some that were already fallen, also. However, one mould in particular seems to show that the lava came through in several waves, with each staying long enough to coat the tree in a new layer. It appears that there were at least three such flows and quite likely a fourth.

Fig. 51. A diagram showing the formation of tree moulds. The lava swept through the existing rainforest, but only remained for a short while, before draining away and leaving the tree trunks burned and coated with lava. Almost all the moulds have a central hole, filling with mosses and new shrubs.

It was a luxuriant rainforest before the lava arrived and the trees were wet. The dampness didn’t save them from the lava, but it took some of the heat out of the lava and briefly protected the bark with a cushion of steam. This gave the lava time to cool and settle around the tree, and not rapidly burn it away. Instead, the lava solidified in contact with the bark.

Fig. 53. It really is dangerous to stray into the undergrowth – the fissures are very deep.

For a time, the forest must have had an extremely weird appearance – bare black-lava covering the ground, the trees dead and probably burned of their bark, now bare and bleached white in the sun. And each one with a jacket of black lava wrapped around it up to its waist. Eventually, the trees rotted away in the hot, wet climate, and left the empty moulds standing starkly above the lavascape. A few collapsed and either remained as horizontal tubes or smashed. Some of the still-standing ones have a perfect round hole down the centre, often with clear impressions of the original bark still imprinted around the internal part of the mould. Others are a joined mass of several trunks and small sprouting branches that were growing as a large clump, instead of a single trunk. Some that were already fallen were buried in lava and then rotted away, leaving horizontal tubes.

Fig. 57. The rounded interior of this mould appears to have several grooves down it – almost certainly where vines clung to the trunk – as many still do.

The Kazamura Lava Tube

A lava tube forms within a flow of lava, because the parts of the flow that cool first are the sides and these can create walls, which confine the flow’s direction. The flow may also crust over as it cools, perhaps in phases. Given the right timing and a supply of fresh magma, the lava will continue to flow beneath the new ceiling crust. It retains almost all of its heat and can resurface many kilometres away from its source at virtually the same temperature as when it entered. Such tubes are common on Big Island – 47 of them are said to be exposed on cliffs around the coast. More recently formed tubes in this area are separate and the volcano has not taken advantage of this system by re-occupying this route.

This particular tube stretches erratically for almost [50km][30 miles = 50km, but you refer to 68km below. Which is beneath the ground from volcano towards Hilo. There is an access point about five kilometres south of the Hilo to Volcano Hwy 11 road, between Kurtistown and Mountain View. The tube was formed during an eruption of Kilauea about 700 ago, as part of the Aila’ua flow. It was re-filled and drained intermittently during eruptions for probably 200 years afterwards. Surveyors rate this as the world’s longest known continuous lava tube with a total surveyed length of [68km]. It is a complex system with a main passage 40km long and other passages about 27km in length. Five separate complexes of mazes have been explored. It also lays claim to being the deepest cave in the USA, at over 1,000m below the surface in places, and has the greatest lava tube span from wall to wall at 21m in one place and almost as high. Throughout its length, there are more than 30 lava falls and cascades over three metres high, the highest being 13.7m. There are several scholarly articles about the cave on the Internet.

Fig. 59. Just within the entrance, the roof is coloured in reds, oranges and greens, through the mass of tree roots that penetrate from the ground above.

Tours are run by a small company called ‘Caverns of Fire’, and are by appointment only – but almost every day. The contact number is +1 (808)-217-2363. When we went, we were the only people on the visit. This was fine, as we could talk with the guide all the time and get personalised information from him. If you look on the Internet, you will see that this is a frequent occurrence, so don’t be shy about it.

We took the one-hour tour, which covered a superb range of features commonly seen in lava tubes and many that are unique to this one. The section of the tube that this explores is around 275m long. It was an upper overflow channel for the main tube, so it was periodically flooded and drained. The lava did not pour through here like a giant red river. Rather, it rose and fell more like the water in a bath. This calm and intermittent flow and flooding is what gave rise to the different features found here.

Waterproof jackets are recommended in case of seepage and long trousers in case of a trip. Armed with helmet, gloves and torches (the tube is not lighted), the entrance is just round the back of the office building among the undergrowth of the forest. It isn’t the fine bridge that appears on some websites, but a duck down over steps and rocks into the cavern, at a place where the roof once fell in.

Fig. 65. A further section of ceiling drips, which are larger than others, with some being 15cm long.

The first feature that is truly amazing is the wall and ceiling section just inside the entrance. The colours are phenomenal, and occur in patches of different shades and hues alongside each other. Long, fine tree roots grow down through the rock, in places quite densely and, in one instance, a root has grown through a hollow stalactite ‘straw’ and hangs out the bottom.

The floor varies from a smooth and beautifully coloured flat surface, where a lava surface gently solidified, to heaps of fallen roof rubble, with variations of lava formations, such as ropey flows, a ‘rose’ of dripped lava. There is also a circular section, where a radiating pattern is claimed to be the result of a single drop of falling lava causing ripples. However, in view of the viscosity of lava and its reluctance to transmit clear ripples, combined with the overlapping nature of many of the ‘ripples’, this seems unlikely.

Other sections of the floor are roughly grooved, indicating a flow suface that was moving as it crusted. Towards the end of the easily-accessible area, there is a double floor, with one flow crusted over to about 15cms. The lava beneath then fell in level by around 60cm and crusted over again. Both surfaces can clearly be seen. Other such changes in surface height are seen throughout the cave, forming benches at different levels along the walls and parts of the ceiling. These are often very clearly differentiated by colour differences, as well as the smoothness of their surfaces and the series of lava dribbles below them.

The ceiling, which is mostly a little above head height and therefore close enough to reveal its details, is festooned with a variety of formations. These are most obviously long drips, which have formed over a period during which the lava level rose and fell repeatedly. This caused the drips to be dipped and dipped again into the lava, each time adding a layer and making the drip thicker and longer. Some of the drips are distinctly bent – a mark of the direction of the slight current as the lava drained away. Some areas of the ceiling are ‘sucked rather than plucked’, that is, when lava separates by being pulled apart, it generally produces a patch of sharp, needle-like spikes. However, here, the lava repeatedly pulled apart, as the level ebbed and flowed, and the sharp needles became more rounded with each coating left behind. The surfaces between them are somewhat reminiscent of the water-formed scalloped surfaces in limestone and ice caves. In places, they have joined together to create curtains, with an indication of the (very slow) direction of the flow.

Fig. 72. Where ceiling drips have been coming from the same spot for some time, these spatter spires are formed. The tallest one is less than 60cm high.

Where drips continued to fall from the ceiling and high parts of the walls, they formed patches of dribbles, like small spatter mounds on the floor and on the side benches. Unusually, these are often a different colour from the hanging stalagmites, as well as having a much rougher texture that formed as they solidified when they landed. In other places, lava straws have formed, hanging from the ceiling. These are hollow and were created in the same way as limestone ones – by water droplets evaporating on the lower tip and depositing a tiny amount of mineral each time.

I imagine that we have explored dozens of lava tubes in the past years, but this has to be the one that stands out for variety of form and colour.

There is also a three-hour ‘adventure’ tour into the main, lower passage, which is for the fit and young, seeking physical excitement. A couple we spoke with said it was excellent and many Internet reviews say the same. However, for old and unfit observers, the one-hour tour covers everything. Go to http://www.travelchannel.com/video/hawaiis-kilauea-caverns for a short video (2 minutes, 34 seconds) presented by the manager and guide, Steve Krucker. The Caverns of Fire’s own website (www.kilaueacavernsoffire.com/) has a short computer-animated sequence of how such a lava tube might have appeared during its active period. Many reviews justly use words such as amazing, unforgettable, unique and astonishing, when describing tours of this tube system.

Flights over the area’s different features

Over the years, we have had a number of flights over the craters and lava flows on Big Island, Hawaii. All have been good in some way – you see great fields of grey lava, hot flowing lava sometimes, with the opportunity to look down into the seething craters, and see the ocean entry lava-falls and the skylights through the crusted lava down into the molten lava flowing beneath. However, flights by helicopter are expensive, often quite short and don’t always stick to where they said you were going. The windows are highly reflective and, if you get a middle seat in the back, you don’t get many photo opportunities. In addition, last year, the authorities seemed to be tightening up on where the helicopters can fly, so going in close over moving lava is generally not a likely option. We got $180 knocked off the price of a two-hour flight for two persons, because we attended a two-hour timeshare presentation (never again), but it still cost $300 each for a two-hour flight. One company guarantees a window seat, but, of course, this is more expensive.

Fig. 75. Looking into a ‘skylight’ to see the hot lava beneath.

Flights may leave from the Hilo area or from Kailua-Kona. Which one is best depends on where you are staying and what you want to see. They usually include lots of waterfalls and the amazingly steep forested valleys of the northern coast. Try www.bluehawaiian.com/bigisland/ or www.safarihelicopters.com/big-island-helicopter-tours/. The photographs are all ones that I took on our last three visits, so you can judge if it might be worthwhile for you. However, we don’t all get the luxury of the US Geological Survey, with a privately chartered flight twice a week, and permission to go anywhere.

Fig. 80. Major steam and splatter explosions, when large amounts of lava hit the ocean.

About the author

Trevor lives near Nottingham, England and is a retired teacher, headteacher and school inspector who has had a lifelong interest in geology, particularly volcanoes and dinosaur footprints. He and his wife have travelled worldwide to visit and climb more than a hundred volcanoes – active and otherwise. A few of these visits have been with organised groups, but most have been independent, and frequently involve camping.

Dr Trevor Watts (UK)

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A night walk to the flowing lava from Kalapana

This was one of the major highlights of our previous trip in 2013. Several local guides conduct walks across the old lava (mostly 1981 to 2013 flows) to wherever the current flow is best viewed. Our lead guide was Dave Ewing ([email protected] or (808) 315-2256) and our group met up at his house, located on private properties beyond the “End of the road” signs at Kalapana. This house is one of the very few to survive the 2010 flow, which came through the Royal Gardens subdivision and into Kalapana.

Fig. 1. A going away party to mark the long-expected event of the house burning at Kalapana on the night of 25 July 2010. My thanks to Darlene Cripps and Gary Sleik for this picture.

We began in late afternoon, with around a dozen people in the group. The walk initially passed the remnants of some of the other homes – a corrugated roof, a fridge, some pilings, and so on, before getting onto the fresh lava. It was almost five kilometres each way and, although the walking isn’t especially difficult, a couple of hours scrambling over very uneven and lose ground can be tiring. Also, it isn’t for anyone of a nervous disposition or unsure footing, and it really does need a guide, even though you can see the rising steam and smoke from kilometres away. Getting back through pitch darkness is more difficult and, as if to prove my point, another guideless group joined ours on the return with an injured member (sprained ankle).

Fig. 2. An hour later – the blazing roof is all that remains. My thanks also to Darlene and Gary for this picture.

The fate of Darlene Cripps and Gary Sleik’s home

The fate of one particular home is well documented. The flow that was working its way through and around the village of Kalapana circled round the back of the house, until it was three-quarters surrounded. Then, it restarted from the front, finally touching the woodwork at the foot of the outside stairs. The house was gone in a blaze within the hour, as the owners, friends and neighbours held a ‘going away’ house-burning party on the night their property went up in flames. 25 July 2010 was the final night for the home of Darlene Cripps and Gary Sleik, who took many pictures and made a DVD of the event and the guilty lava. The charred foundations are now under 12m of lava. The lobate lava that covered the area and burned the houses down was fluid and only about a 30cm deep at any one time. The corrugated tin roof collapsed after less than an hour of the fire, but then ‘floated’ on top of the lava, as it continually inflated beneath the roof over the following months.

My thanks to Darlene and Gary for allowing me to use their photographs (Figs. 1 and 2). Gary is now rebuilding his home on the same 23-acre plot; and Darlene manages the accommodation where we stayed in Kaimu: http://www.vrbo.com/460059.

We arrived in the vicinity of the moving lava just before sundown, enabling the taking of several pictures of the lava formations in the daylight. The warmth of the ground was suddenly noticeable and, as the sun disappeared, so the lava seemed to come to life. All around us, there were red glowing patches and streaks – many of them moving slowly or taking on a sudden spurt. We were completely surrounded by small flows less than a metre across. In the daylight, they weren’t visible as molten lava, but with the sun down, it was like a lighted garden park. We stayed in the area for an hour or so, watching the lobes and fronts advancing and swelling; crusting, crinkling and restarting as long tongues, pushing the surface into wrinkled, ropey masses. Other groups were there, with or without guides, but it only added up to about 30 people all told. A few people pushed sticks into the moving surface to watch them catch fire and a few tried jumping over the molten tongues. There was no feeling of any danger (other than from foolishness), as the lava moved quite slowly and the guide was keeping a check on the overall situation. Apart from a few over-excited visitors, most people seemed to have a reverential view of the world-creating happenings around them and simply watched the new land being formed in near-silence. What made the most noise was the surface of the lava as it cooled – a thin, but rigid skin forms as the lobes slow down and settle, but the leisurely continuing movement cracks this and sends flakes scattering away, sometimes several metres into the air. The effect is much more dramatic when it rains and cools the lava surface more suddenly, at which time, there can be a veritable cloud of flying flakes above the lava.

Fig. 3. By May 2013, the roof is rusted and the forest is gone.

From this vantage point among the moving flow, it was possible to look down over the cliff edge (about 30m high at that point), to watch lava slowly pouring towards the sea from a variety of points down the cliff face, where small tubes had their openings. This gave an unearthly glow to the whole water surface and rock faces. However, it wasn’t possible to see the point where the lava actually entered the water.

Fig. 4. The plume of steam and fumes can be seen for miles around.

Watching the lava forming, moving, taking shape all around is the only way to understand the wondrous nature of the stuff – how the various shapes and twists are created, and take on such superbly varied (yet similar) shapes and patterns. Observing it actually happen gives so much more meaning to what you are looking at when walking on cold lava here or anywhere else in the world.

Fig. 5. As evening falls, all around there seem to be glowing patches and cracks that you hadn’t noticed in the full sun.

The walk back to the house and car parking was in complete darkness, apart from carried torches or flashlights. It would definitely not have been easy without a guide, especially as the lava flows here were changing on a daily basis. It only takes a moment for one lava front to stall and another to break out close by, or at a distance of a few hundred metres, for there to be problems. The internal pressures within lava flows are constantly built up and released – inflating one lobe for a time and stalling another. There had been news reports of two people being severely injured earlier in the year, when a foot went through the newly-formed lava skin. During December 2014, it wasn’t possible to do this walk, as the lava stopped moving in this direction late in 2013. Once the current ‘June 27’ flow has settled, it might well be possible to conduct similar day or night walks to the new flow and there are several Internet sites with close-up footage of the flows already. Or Madame Pele might change her mind again and send the lava flowing southwards to the sea once more. Check the Hawaiian Volcano Observatory (HVO) site for daily updates and maps at http://hvo.wr.usgs.gov/activity/kilaueastatus.php or just Google HVO.

Fig. 6. Moving in lobes and rope patches down the hillside, the lava seems to cover the whole slope.

The lava-falls at the ‘Ocean Entry’

In 2008, we visited this area for a short stay and it was a time when the lava was entering the sea a few kilometres or so from Kalapana. The access was controlled by the Civil Defence, just past the ‘End of the road’ signs on Highway 130, where the lava had swallowed the road in a number of flows over the previous years. The column of rising steam and smoke could be seen from at least three kilometres away in Pahoa, driving from Hilo. There was a large car park and a street market, with dozens of enterprising stallholders, some with general merchandise and others with lava-related items, such as lights, drinks, lava ashtrays and photographs of the lava and lava caves. Some of these photographs had been taken from the stern of boats that had backed up perilously close to the lava-falls, to peer inside the active tubes from which the lava was pouring out. The cameramen had to wait until a large wave lifted them to a height sufficient to see inside the lava tubes and take a quick photo, then rev up and depart swiftly. For such bravado, they deserved every cent of their charges for the terrific quality of pictures.

Fig. 7. The sight-seeing boat is getting a closeup view of the lava entering the ocean.

A twenty-minute walk from the car park led to a viewing area a few hundred metres from the active drop into the sea. As we approached, the plume was extremely impressive, particularly the sight of tornadoes within the plume and coming from it. These spun out of the main, hot centre of the steam, whirling away, spinning and twisting until they cut loose and drifted off, to be replaced by another. Closer approach was not permitted, although we did see a few people going over the private land closer to the lava. It was impressive by daylight, with great columns of smoke and steam shooting skywards over our heads. Blasting up through the steam, there were frequent spatter explosions of red lava flying high. Within the steam plume, there were constant sudden updrafts, like vertical tunnels of rock and steam sucking powerfully upwards; followed a moment later by a fall of fine ash, turning the cloud to a mass of dark descending curtains. At times, there would be an especially loud thump, denoting a steam explosion, where a particularly large mass of lava had tumbled into the water and flashed some of the sea into steam. These would result in huge masses of lava fragments and hot cinders hurtling perhaps a hundred metres upwards, and lots of oohs and aahs from the audience.

Fig. 8. Lobes of glowing lava cool within a minute of forming; the flakes that spit off can be seen on the grey cooled patches.

Although it wasn’t possible to see the lava falls hitting the waves, the sea was visible a little further out. The water was steaming heavily and giving rise to whirling tornadoes across the surface. They varied from a meter or so across to the size of a boat – and there was a boat among them at times. This looked incredible – imagine the view that those people must have had – until a particularly large blast sent glowing fragments over a huge area and the boat retreated. Local gossip says that one boat owner has lost two vessels on these forays. Sometimes, there was just the one tornado spinning away and, at other times, there would be a train of them heading out to sea, to disappear as they cooled and lost their source of power.

Fig. 9. A beautiful runnel of ropey lava already beginning to crust over, even as it is only exposed for a few seconds.

Even more amazingly, there were several helicopters buzzing around the whole steaming plume. This was a must, so we were up there two days later as part of a volcanic highlights helicopter ride. We did get as close as it appeared from the ground and it was very spectacular. Photographs were difficult to take, as the craft was being buffeted about in the hot swirling air. Views looking down into the exploding mass are especially interesting, when the fragments are heading straight up towards you.

Fig. 10. A final look back at the spectacular steam cloud lit from beneath, as the lava-falls enter the water.

As the sun dropped, so the glow from the lava picked up and the steam clouds were lit from beneath in great roiling masses. These were extremely spectacular – red clouds blasted by frequent explosions of lava fragments, rising majestically into the gathering gloom. Particularly noticeable was the colour contrast between the glowing steam clouds here and the sulphurous clouds emanating from Halemaumau far away in the background, illuminated by the sun behind them.

In the later evening, the glow within the plume intensified from the dull red ball that it had been and took on the appearance of boiling swirls, illuminated by explosions and short-lived fire fountains. This was breathtaking. The viewing area is not open all night and is locked at 9.00pm. The car park is still there and accessible to lava-walkers during the daytime, and so are most of the signs warning about the eruption and the opening/closing times – six years after it ended. However, this is likely to change very shortly, as this is the Hwy 130 road that is being reconstructed across the earlier flows in case the new lava blocks it north of Pahoa.

Fig. 11. A view of the steam plume from several kilometres north, near the town of Pahoa. This illustrates how enormous it was and how high it rose into the sky.

Fig. 12. A helicopter against the steam cloud. The ‘V’ shape in the bottom right quarter is an airborne tornado, originating within the plume and rapidly spiralling directly away from the camera.

Fig. 13. A particularly strong steam explosion, as a result of a large mass of lava falling into the ocean and blowing itself to fragments.

Fig. 14. The resulting heavy ash and fragments fall after an especially violent explosion. The ridge on the right is made of ash and cinders, which have been deposited during the five-month period that the ocean entry was at this point.

Fig. 19. Into the evening, the lava explosions take on the appearance of temporary fire fountains.

Boat trips to the lava falls

Inspired by seeing where the boats went in 2008, we decided to take a boat trip along the cliffs to experience all this for ourselves. At around four in the morning, we took a boat out the Pohoiki Harbour at Isaac Hales Beach Park, about 20km northeast along the 137 road from Kaimu. Then, it was a rough boat trip back along the coast for about an hour and a half, feeling battered and queasy. The paucity of steam clouds should have alerted us more. Arriving at the scene of the lava falls, all we could see was the exit of one tube partway down a cliff face. Inside, there was the glow of lava, but the active flow had stopped, maybe a couple of hours before we got there. We checked further along the coast for a half-hour, where other falls had been flowing the day before, but there was nothing and, when we returned to the first large tube exit, the glow was entirely gone. After five months, it had stopped moments before we arrived. True, the cliff face was interesting, with a vertical cross-section of the newest land on earth, but it wasn’t what we’d come for and I still haven’t recovered from the disappointment. Even the giant waves battering the cliffs in spectacular crashes of spray didn’t help.

Fig. 20. The cliffs, topped with mountains of black volcanic sand. These are actually obsidian fragments, which are still steaming with internal heat.

We had another go in 2013 and our early morning boat cruised along the face of the cliffs as lava poured into the ocean, getting as close as a few metres and considerably less than ten metres at times. It was absolutely spectacular and, when the steam cleared, we had fleeting glimpses of red-hot lava falling and dribbling down the cliffs. I think this added to the awe – making it something special when the steam blew aside for a few moments. We went to several sites along the cliffs – over a distance of perhaps a kilometre and had superb views of lava dropping five or ten metres in some places, or as a broad sheet in others.

However, the most utterly wonderful trip was an evening voyage the following day, when the lava was flowing at its height. Seen from kilometres away, the steam clouds were very promising and, even as we approached the first mass of fire and steam, another one started up about a hundred metres further along. The boat captain said that one group of falls that was there in the morning had vanished altogether, showing that they are in a state of constant change. As we were watching during the evening, another set of bright falls started up a few hundred metres further along the cliffs.

Fig. 26. An idea of the scale and closeness of the boat to the falls – less than 20m away for much of the time.

The evening there, tossing about on the waves 20m away from lava falls in the dark, was the most memorable sight I have ever experienced – and in 70 years, I’ve seen some good ones. Brilliant lava streams poured down the cliff faces into the red-reflecting waves. Steam flashed everywhere. There were exploding blasts from time to time, sending lava bombs into the air. Some of these landed close to the boat and fizzed madly around for a minute, before succumbing to the cooling water – a bucket of seawater hauled aboard was almost too hot to place a hand in it. There was also water to douse any lava that might land on the decking. Strangely, there wasn’t any feeling of danger, even though lava bombs, almost half a metre across, were whizzing through the air and landing in the water around us. Our boat moved to different locations along almost a kilometre of the cliff face, where the lava was pouring into the waves, sometimes in high vertical falls, sometimes splashing and washing over rocks created only moments earlier. When, or if, they start up again, they have to be the highest priority on anyone’s ‘bucket list’. I count myself as one of the extremely fortunate few to have witnessed such an awesome sight.

Fig. 28. A memorable ending to a memorable evening, as the boat pulls away for the return to Pohoiki Harbour.

A walk on the lava at Kaimu and Kalapana

In this area, from just over a kilometre east of Kaimu, down through Kalapana and into the national park, there are innumerable vistas of multiple forms of lava. Best seen in low light when the shadows etch out their forms, they are especially spectacular at sunrise and take on warmer glows in the sunset.

This area of lava has a complex history. The village of Kalapana was built on old lava flows and was swamped by new ones in phases from July 1986 to February 1992. The whole eruption had begun on 3 January 1983, when fissures opened up along the eastern rift zone, east of Kilauea’s summit. Fire fountains up to 480m high filled the air, but very quickly the outpouring coalesced at one spot. This formed one main cone, about 250m high forming a hill. This cinder and spatter cone was informally coded ‘O’ by the observing volcanologists, who were surveying a line of fissures and vents. It then became Pu’u O (Hill O) and then Puʻu ʻŌʻō, which means both the o’o bird and Pele’s (the Hawaiian Goddess of the Volcano) stick for digging volcanic pits.

Fig. 38. A mound that was pushed up to exude small runnels of lava down its slopes. There are many such cones near the national park boundary, west of Kalapana.

The first three years of eruption produced mainly a great amount of a’a lava, which slowly spread far and wide from the two vents of Puʻu ʻŌʻō and Kupaianaha (slightly to the east of the main cone). Afterwards, these vents flowed fairly vigorously, as the exuding lava became hotter and more fluid. Presumably, the magma chamber was refilling with hotter, more fluid magma from beneath. It flowed away as pahoehoe lava – ropey and lobate – that formed long and wider-spreading smooth-surfaced flows. These crept over the flatlands and swept further and faster down the steeper cliff and hillside sections, south for up to 13km, covering many square kilometres of forest and cultivated land. The lava eventually went across the Chain of Craters Road (HWY 130) that runs near the coast. It did this at various times, sometimes over the re-built sections of road. Very frequently, the fluid lava was again replaced with slow a’a flows and these, in turn, were often overrun by more pahoehoe flows. By the time it finished, the eruption had buried some parts of the road up to 15m deep, over a distance of 13km. Towards the end of the eruption, the lava was again flowing towards and into Kalapana in a series of pulses. A number of homes were swallowed during the summer of 2010, and with the phase not ending until late 2013 or possibly early 2014.

The lava is basic basaltic lava, with a relatively low silica content, which makes it quite fluid. Therefore, close to the issuing crater, it will flow relatively swiftly, up to about 16kph, if it is confined within a channel where the edges or walls have cooled and solidified, or if contained within an underground tube. Such tubes are often formed where a channel has crusted over, but the lava continues to flow beneath the ‘roof’. One such tube towards Hilo is almost 66km long – the Kazamura Tube. (Others include: Thurston, on the rim of Iki Kilauea; Kaumana just west of Hilo; and the Hu`ehu`e lava tubes, a few kilometres north of Kailua-Kona.)

Mostly, such flowing does not produce a large feature on the surface. It mainly acts to get the lava somewhere else quickly. This can be many kilometres away from the originating crater or vent, with little loss of heat and fluidity, so it may then break out of its crusty lid far from where it started. Such breakouts are usually where the gradient slackens off and the lava has to slow down. It ponds back and needs to burst out of its constriction. Once it is exposed on the surface, it is generally still hot enough to flow, but the slope is not sufficient for it to move rapidly and wildly away. Rather, it spreads slowly, seeping onto the landscape, and the surface cools quickly, usually within a minute of being exposed if the flow is slow, to become stiff and then solid in the space of a few minutes.

Fig. 40. White encrustations, in this case, the result of mineralisation, not burned trees.

At the main time of their desolation, beginning in 1990 and lasting most destructively for nine months, much the same thing happened around Kalapana and Kaimu. Flows burst out from channels and tunnels, and began to spread over the land, changing direction, and stalling and restarting on a daily basis. The effect of all this was inflation of the surface of the lava and unpredictable breakouts throughout the flow. This gives rise to an infinity of fascinating shapes to delight the eye and the imagination. It is all the result of cooling lava that swells, becomes wrinkled, seeks a finger-like way out or pops out in bubbles. As well as the inflation, the loss of lava from under the surfaces causes deflation and the whole mass can sink again and crack apart. This very changeable process continued until 2014, with the exact point of ‘ocean entry’ changing its location now and again.

Access to this now cold flow in the Kalapana district is easy and unregulated. We were staying in accommodation at Kaimu that had its own private access to the lava beds, but it is equally possible to stop along the road and walk directly onto the lava or drive to the end of the road at Kalapana. There is an irregular farmers’ market here and a regular general store that was a restaurant/diner until recently). From the public access at Kalapana, a walk in any direction will take you over magnificent formations of lava. Probably, the most beautiful are a little to the east, where the lava flowed over and through the rainforest and found its way to the sea. The flow is less than a kilometre wide, between the forest/road/buildings and the low sea cliffs, but it seems to have examples of all possible kinds of pahoehoe formations.

It is still very apparent that the lava here came in phases: in some spots, it may have piled up several metres in a day or a week before breaking out sideways and flowing along another route for a time, before again stalling at one front and breaking out elsewhere. In many places, it is also clear that, the flows were very thin – only a couple of centimetres or so thick – being shortly overspread by another flow and another and another. This had several effects: where the lava has split apart and exposed cross sections. The layers can be clearly seen in different textures and surfaces, and often in vividly differing colours – yellow, orange, red and black, which is often evidence of steam that oxidised the lava while it was still hot, perhaps because there was heavy rain at the time of the flow or because of later water and steam being forced through the cooling lava.

Even as the lava flows cooled, they were being disrupted from the sides and from beneath, where fresh masses could accumulate beneath the extant surface and the pressure splits the solidified surface layers apart, producing deep cracks. Where the lava re-commenced its flow beneath the earlier layers, it often squeezed between the successive layers. This produced the effect of layered cream cakes, with the lava being pressed out sideways and exposed where the cracks from earlier disturbances had opened up the surface. In such cracks, there are often numerous layers of red lavas forming the base material, with the newer, squeezed-in lavas remaining black. The effect in some places is very striking. In the bottom of the chasms formed by the cracks, there is often a pooling up of lava or even an overflowing of fresh lobes onto the surface. However, other cracks, equally deep, may not have any new lava in them. These are more likely to be the result of the surface all around sinking and leaving part raised, with gravity causing the cracks, as the surface is left unsupported by the drained-away lava.

This must surely be one of the best – if not the best – places in the world to see pahoehoe lava. It exists here in a perfection of forms – in great cables of thick ropes that piled and curled over one another, so slowly and remorselessly. Of course, they are not ropes, even rocky ones – they are the wrinkling surface of the flowing lava. As it cools on the surface, it is dragged along, pushed aside or forward, stretched or compressed, giving rise to all the surface forms that are created. Bubbles arise. Some burst, with others freezing and remaining forever enclosing their gaseous contents. Solid ‘blebs’ can push through the thin layers and will either flow aside for a time, as a briefly-wandering tongue of lava, or cease where they surfaced to produce a plain ball in the middle of an otherwise smooth or finely-ropey patch of lava surface.

In other places, the lava surface has been partly sucked back into the depth of the flow, producing whirls and whorls of ropey surface. At times, the flows seem to have moved in pulses, producing a surface pattern that is striped rather than furrowed.

Where the surface had crusted and then been disrupted, sections of the surface sheets have been turned over or on their sides. Commonly, these surface sections have then been fixed in a vertical position and they can now be seen with the graduated steam-oxidisation layers cutting across the surface of the ropey lava. This clearly indicates that this oxidation continued long after the lava had ceased to move and flow. In other places, the steam has seeped through cracks in more solid sections of flow, and has changed the composition of the lava and coloured it much paler – often a white or yellow tone alongside long thin cracks. The yellow tone is mainly due to formless sulphur deposits, which do not usually form the classic needle crystals. However, the white deposits can be the result of either ash from incinerated trees or mineral deposits of manganese and other trace elements. In the case of burned trees, the white material is spread loosely on the surface and there are usually other traces, such as a mould-hole where the tree stood or the remains of branches. With mineral deposits, the white material tends to be around and in cracks.

Although the overall impression of lava is a dark steel or silvery grey, blue and green are common in the detail of the lava. This is especially so on the undersides of broken pieces, which have not been exposed to weathering for long. Even a brilliant yellow-silver is seen on some freshly exposed. The potential colours depend on the precise mixture at the time of extrusion and cooling. Commonly found minerals in mafic lava such as this include silica (the oxidised form of silicon), which is the main component of quartz, olivine, pyroxene, amphibole and biotite mica, along with magnesium, iron, aluminium silicate and potassium. Mostly, they are impure, oxidised or mixed into each other.

Fig. 41. The surface of the lava can vary wonderfully in its colouration, the result of variations in precise mineral content, temperature and speed of cooling. These are four examples from the small area between Kaimu and Kalapana; each less than 30cm wide.

The time taken to cool down is surprisingly important, because cooling slowly allows some minerals to separate out and crystallise, and give a more distinct contribution of their own colour to the surface. This is called fractional crystallisation and is seen well in silica-rich lavas, such as this basalt. Some exposures will change colour as they are exposed to the weather, for lava that is initially blue, as it loses its blue lustre and becomes greyer. Silvery pearl-grey surfaces frequently become darker after prolonged exposure. Heavy rain at the time of eruption can cause increased oxidisation and a subsequent intensification of colouring, especially in iron-rich lavas. Rapid cooling on a cold day can produce a glassy surface, which will have its own range of refractive colourations that vary a little, according to the angle they are viewed from.

An unusual feature – we hadn’t noticed it before, anyway – was the imprint of solidified flows on the underside of later flows. It seems that one flow had travelled over an earlier one, cooled and solidified. Later, as the whole flow was disturbed by new flows, the surface broke up and the two layers split apart. In rare cases, the underside of the upper layer bears the imprint of the surface of the lower one – a sort of negative pint or trace fossil. The example here is from the cliff-top close to Kaimu.

More commonly, where semi-molten layers have been forced apart (perhaps by gas intrusions), the underside of the higher one displays ‘suck and pluck’ textures. These are very sharp and jagged under-surfaces that have been plucked apart while still partly molten. Sometimes, these pull completely apart and create slabs with one extremely sharp surface; and sometimes they do not completely separate and produce a cave-like gap, with its own fangs.

Fig. 43. Where the crusting surface has been incompletely pulled apart, the formerly joining surface can be extremely sharp and jagged.

From the road, the coast here is just a few hundred metres across from the lava field. The cliffs are not high – mostly about ten meters to perhaps 30m in places – but they have black-sand beaches and great Pacific rollers crashing onto them. To see the new land being already broken up and washed away by huge waves makes for an awesome pause from walking the lava. Much of this coast was formed around 1992, when the old coastline was overwhelmed and a new one extended just under a kilometre outwards in places.

44. Along the coast at Kaimu. The a’a flow tumbled over the pre-existing cliff and now makes access along the coast difficult.

To the northeast of Kaimu, the cliffs are topped with a’a lava and are not easily accessible from along the beach front or through the rainforest. Those a’a flows can be accessed from the Hwy 137 road, between Isaac Hale Park and Kapoho.

Tree and fruit impressions

In a few places, there are impressions in the lava of tree trunks. These are most spectacular and prolific just west of the end of the road at the existing part of Kalapana village, where the general store, village and car park are located. They are all within one kilometre of the road and are easy to find.

Fig. 48. Fossilised impression of an oil-palm seed, almost head-sized.

As they were formed in the last few years (since 2008), many of the impressions are very clear and fresh. They were formed as the lava crept through the forest and farmlands here, and set fire to the trees and brushwood. Some trees remained standing and eventually burned away, leaving a round hole where they had stood in the lava. Others fell onto the still-molten surface and burned there. These were a mixture of ohio trees, oil-palms, coconut palms and lauhala trees, as well as a variety of smaller shrubs. Their fruit (coconut and hala seeds) are also remarkably well preserved. These are already trace fossils and will continue to be so when the lava next comes this way and buries them again.

Fig. 50. Where once there was a tree – now only the hole and the space where the roots had been.

It is very exciting to explore this area and find one print after another, each better than the last. Some trees have been completely covered by the lava in places, while others have rotted or burned away, leaving a tunnel in the lava, in some cases forming a network of small ones where trees and branches were piled on top of one another. These holes and tunnels are of benefit to future growth here, as they form traps for seeds and for rotted material for them to take root in, as well as to gather water.

Fig. 53. A great many of the cracks in the lava closely follow the line of tree trunk imprints, probably because of stresses that built up in the lava by the production of sap-steam, as the tree was boiled and burned.

In the final part of this article in the next issue of Deposits, I will continue to discuss some of the highlights of our trip to Big Island, Hawaii.

About the Author

Trevor lives near Nottingham, England and is a retired teacher, headteacher and school inspector who has had a lifelong interest in geology, particularly volcanoes and dinosaur footprints. He and his wife have travelled worldwide to visit and climb more than a hundred volcanoes – active and otherwise. A few of these visits have been with organised groups, but most have been independent, and frequently involve camping.

Dr Trevor Watts (UK)

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