#lithology

Back in the Late Jurassic Period, North America, Europe and Africa were next door neighbors.

This is reflected in the similarity of the lithology, and fauna of the rocks. In North America, we have the Morrison Formation, in Europe we have the Lourinha Formation, and in Africa we have the Tendaguru Formation. All of these are contemporaneous or sister formations.

Stratigraphy

The Tendaguru Formation is approximately 177 m thick and broken up into five members: Lower Dinosaur Member (cross-bedded, fine-grained sand and siltstone w/interbedded clay), Nerinella Member (trough cross-bedded and massive sandstone indicating a tidal channels, sandbars and beaches),

Middle Dinosaur Member ( ripple, cross-bedded, fine-grained calcareous sandstone and siltstone and massive to crudely bedded siltstone and claystone indicating tidal flats and lagoons),

Indotrigonia Africana Member (calcite cemented sandstone, conglomerate, thin claystone, and siltstone with sandy limestone indicating tidal and deltaic channels),

and the Upper Dinosaur Member (ripple, cross-bedded, fine-grained sandstone and siltstone with interbedded claystone and micriitic carbonates indicating tidal flats).

The Lourinha Formation is about 200 to 1000 meters thick and is broken into about 5 members: Praia da Amoreira Member (massive mudstone with meter thick sandstone lenses and calcrete layers indicating a meandering river system),

the Porto Novo Member (cross-bedded sandstone indicating a deltaic system), the Praia Azul Member (marl and mudstone indicating brief marine transgression),

and the Santa Rita and Assenta Members (mudstone, caliche, shelly carbonates near the top indicating a landward side of a deltaic system) which are equivalent members from different basins.

The Morrison, as stated previously, is about 200 m thick and consists of 11 different members. I will not go into detail about them again but it should be noted that the formations are approximately the same thickness and made of primarily sand, silt and mudstone.

DINOSAURS

Now for the other fun part: the dinosaur fauna. There are some dinosaurs that are shared between two or all of the formations. These include Ceratosaurus nasicornis in the Morrison and a possible Ceratosaurus in the Tendaguru

and in the Lourinha, Torvosaurus tanneri in the Morrison, Torvosaurus gurneyi in the Lourinha, and a possible Torvosaurus species in the Tendaguru,

Allosaurus fragilis in the Morrison and Allosaurus europaeus in the Lourinha,

Dryosaurus altus in the Morrison and a possible Dryosaurus species in the Lourinha,

Miragaia longicollum in the Lourinha and possibly Miragaia longispinus in the Morrison. Though if that's true, the genus would be Alcovosaurus because that was named first.

And then there are the dinosaurs that were similar to each other in each formation. Filling in the niche or living alongside Dryosaurus was Dystalotosaurus of the Tendaguru,

Eudryosaurus in the Lourinha, and Nanosaurus in the Morrison.

There's Draconyx in the Lourinha and Camptosaurus in the Morrison as early iguanodonts.

Kentrosaurus in the Tendaguru, Dacentrurus in the Lourinha and Stegosaurus and Hesperosaurus in the Morrison are the main stegosaurs.

For ankylosaurs, there is Dracopelta in the Lourinha and Mymooropelta and Gargoyleosaurus in the Morrison.

Then there's Dicraeosaurus of the Tendaguru and Suuwassea of the Morrison.

Giraffatitan of the Tendaguru, Lusotitan of the Lourinha and Brachiosaurus of the Morrison all represent brachiosaurs.

Janenschia of the Tendaguru and Haplocanthosaurus of the Morrison represent early sauropods.

Tendaguria of the Tendaguru and Zby of the Lourinha are even earlier sauropods.

Torneiria of the Tendaguru and Deinheirosaurus of the Lourinha are the diplodocids that match up with the bagillion in the Morrison.

Lourinhasaurus is the camarasaurid representative of the Lourinha.

The Tendaguru and the Lourinha have early carcharadontosaurs in the forms of Veteruristisaurus and Lusovenator.

Lourinanosaurus is the European equivalent of Marshosaurus in the U.S.

And Elaphrosaurus of the Tendaguru is the small to medium-sized equivalent of Tanycoalgreus in the Morrison.

Kyanite, Quartz, and Phosphorus Garnet found in formations of ultra-high pressure Amphibole Quartz Garnet Gneiss, and Garnet Schist.

Stratigraphy is an important piece of vocabulary for paleontology. It is a branch of geology concerned with the relative position of strata (rock layers) and their relationship to the geologic time scale. It is primarily used for sedimentary and igneous rocks (metamorphic rocks don't tend to layer).

Nicolas Steno, a Catholic priest, established the basis for stratigraphy by introducing the Law of Superposition, the Principle of Original Horizontality, and the Principle of Lateral Continuity.

In other words, all rocks are deposited horizontally,

are laterally continuous,

and the oldest rocks are on the bottom.

There are three major branches of stratigraphy: lithostratigraphy, biostratigraphy, and chronostratigraphy.

Lithostratigraphy looks at the variations in lithology (physical characteristics of rocks) such as vertical and lateral bedding, and reflects changes in depositional environment (river, lake, desert).

Biostratigraphy correlates rock layers using fossils. This is based off of William Smith's Principle of Faunal Succession.

wherein fossils flora and fauna succeed each other in vertical layers and can be found over wide horizontal distances.

Lastly, there is chronostratigraphy which aims to put an absolute date (an actual number) rather than a relative date on rock strata. This means we can tell you where on the geologic time scale a formation belongs as shown below.

I personally love stratigraphy. It involves a lot of rigorous outdoor adventuring including hiking, mapping, drawing, picture-taking, and sample collection. In fact, I am currently working on a stratigraphic paper for our Evil Tree Bonebed. It's taken a few years but we should be done soon! I'll share when we are finally published!

I use the word "member" a lot and no it's not in relationship to an exclusive group. Well, not really. A member is a lithologically distinct part of a formation. Members do not need to be mappable to the same scale as a formation but sometimes they are large enough to be.

The Morrison Formation has 11 members: the Bluff Sandstone,

Bluff Sandstone Type section near Bluff, Utah

Brushy Basin Member,

Brushy Basin, San Rafael Swell, Utah

Fiftymile Member, Jackpile Sandstone,

White Jackpile Sandstone, Jemez Mountains, New Mexico capped by Cretaceous Dakota Sandstone

Ralston Creek Member,

Ralston Creek Member, Fremont County, Colorado

Recapture Member, Salt Wash Member

Salt Wash Member, Evil Tree Quarry, Colorado

Tidwell Member,

Red Tidwell Member muds capped by Salt Wash Member channel sandstones Cisco, Utah

Unkpapa Sandstone,

Unkpapa Sanstone, Black Hills, South Dakota

Westwater Canyon Member, and finally, Windy Hill Member

Windy Hill Member, Glendo Reservoir, Wyoming

So as you can see, there are similarities and differences between all of these members. To get an idea of how they are work together, here is a comparison through Wyoming, Utah and New Mexico.

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