Geology Rocks

(by ~ Floydian ~ )

The deformation in the Grand Canyon These are the same two units I showed in the last post moving up the Grand Canyon, but the setting in this photo illustrates an important part of the story; the deformation. These rocks record the building of what was once a mighty mountain range that has now been worn away. In this photo, the Zoroaster granite and the Vishnu Schist are seen in their typical state. The schist was once sedimentary rock trapped in a continental collision. The granites intruded them, heating and recrystallizing them to metamorphic rocks. Meanwhile, far above these rocks, mountains were being built. The pressures of the mountain building process twisted and folded the hot rocks deep below. Similar features are observed in the deepest parts of many mountain ranges when they are exhumed; twisted layers of granite and metasedimentary rocks. The directions of the folds vary somewhat but they generally record the direction that the rocks were moving, constraining the impact of an island arc with the continental mass to the North. The ages of the deformation in these rocks vary from 1.70 to 1.68 billion years ago (a 20 million year pulse of mountain building!). These rocks started at the Earth’s surface, were buried 20+ kilometers deep, and then within the next 100 million years brought back close enough to the surface to stop the metamorphic processes. A truly twisted path! -JBB Image credit Penn State https://www.e-education.psu.edu/geosc10/l10_p4.html Previous posts: https://www.facebook.com/photo.php?fbid=71718732167564 https://www.facebook.com/photo.php?fbid=717596974968016

More displays from the Tellus Science Museum in Cartersville. So many colours…!

Given that the admission was almost as much as at the Natural Bridge, we’d probably not come see the caverns again. But at least we can say we saw them.

Humans will now be forever inscribed into the Earth’s geological history. Our everlasting signature? Plastic-infused stones. The newly identified stone, according to a report from The Geological Society of America, has been officially named plastiglomerate. It is formed when plastic trash melts and fuses together with natural materials such as basaltic lava fragments, sand, shells, wood and coral, resulting in a plastic-rock hybrid. Researchers say the new material is likely to last a very long time, possibly becoming a permanent marker in Earth’s geologic record. In the photo above: An example of clastic plastiglomerate found on Kamilo Beach. Clastic type is a combination of “basalt, coral, shells, and local woody debris” that are “cemented with grains of sand in a plastic matrix.” (via Plastiglomerate: The New And Horrible Way Humans Are Leaving Their Mark On The Planet)

Check out the crazy patterns on these Seraphinite tumbled stones! www.thegemstoneco.com #gemstone #crystal #beauty #nature #seraphinite #rock #geology #nofilter

Geologic Clock It really is hard to fathom the scale of geologic time. The recent TV series “Cosmos” used one favorite trick, compressing the history of the universe into a single calendar year. This graphic is a different setup, showing the age of the Earth on the face of a clock. If we tried to picture how long our lives are on a geologic timeline, the bit of the planet’s history that we occupy barely registers. The Earth is right around 4.56 billion years old. If that length of time were compressed into 12 hours, then each second on the clock face would represent over 100,000 years. 1 second ago on this clock face was during the start of the last glaciation. During that last second, 90,000 years of glaciation and the rise of the entire human civilization took place. Many of the major events in evolution are shown on this clock. The appearances of land plants, land animals, animals in the oceans with hard parts, and multicellular life all are shown. There Yesterday, we referred to an era of time in the Precambrian covering nearly a billion years; that is ¼ of this clock. Even geologists are used to thinking of time periods like the Cambrian as a long time ago, but the last 540 million years is but 10% of this clock, equivalent to an hour and 20 minutes. Some quibbles could be taken with exactly where the dates are hung on this clock, but the mental exercise of comparing all of human civilization taking place in a tenth of a second is hopefully an interesting way to think about geologic time. -JBB Image credit: (public domain label):http://en.wikipedia.org/?title=Talk%3AGeologic_Timescale#mediaviewer/File:Geologic_clock.jpg Yesterday’s post: https://www.facebook.com/photo.php?fbid=706357562758624

Age of oceanic crust

labradorite

via The Field Museum.

Viva La France by LadyChernobyl