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Where one rock stops, and another begins... Snapped on the Portuguese coast, the photo depicts a break in the sedimentary record, where rocks were eroded for a period rather than deposited, often bearing the tell tale signs of adventures in geological time. Such breaks are called unconformities, and when the rock layers are bent at different angles like this outcrop, they are called angular.
Seymouria This little critter is a fossilized remnant of an organism from a genus known as Seymouria. They lived in the early Permian, just under 300 million years ago, and were widespread across North America and Europe at the time Pangaea was being assembled. Adult versions of these were about 5 centimeters long.
2020: Sequence of Little Blowhole operating. This blowhole was formed from a column dropping out in the Blow Hole Latite, the basal member of the Gerringong Volcanics (late Permian).
This is an incredible fossil amphibian (Sclerocephalus) plate. It is two Sclerocephalus, the larger 13.6" and the smaller 9.2". These are wonderfully preserved amphibians. Areas of skin, legs, and hands/feet can be clearly seen. The shale it is preserved on measures 17.0" x 15.5" and has been backed with fiberglass for stability. The fossil beds of Pfalz in southwestern Germany have yielded many spectacular Permian fossils for many years, but this location has been closed to collecting for decades - making such specimens increasingly rare on the market. The Rotliegendes series of mud and siltstones is renowned for its abundant fish and amphibian fossils and this stunning assemblage is a perfect representation of aquatic life that thrived in the area 285 million years ago.
Salt mine of many hues When sea evaporate, often time and again as climate oscillates, very thick zones of salt can result, such as the Permian era (roughly 300-250 million years ago) Zechstein that underlies much of Europe. Near the type locality for the era near around the Russian city of Perm is an abandoned salt mine, where the evaporating waters were rich in potassium as well as sodium, and a mixture of evaporite minerals were deposited. These have created amazing swirls and psychedelic patterns om the tunnels, made of mixed halite (rock salt) and the potassium magnesium chloride mineral carnallite.
Branchiosaur Apateon and dissorophoid Micromelerpeton, two temnospondyl amphibians from the Permian of Germany
The Paris basin.
The site on which the Romans built Lutetia (Gallo-Roman Paris) is a classic example of a sedimentary basin that has been filled with a wide diversity of sediments since the Permian era. It provides the lovely golden limestone you see in the city's buildings, and perhaps more importantly the terroir for some of France's best wines, including Champagne and Chablis. The basin is drained by the Seine river, beside which one can laze in a cafe sipping a glass of wine while reflecting on its geological history, and the impact that deciphering it in the 18th and 19th centuries had on the development of the disciplines of geology and evolutionary science.
Sited between the Armorican massif in the west, the Massif Central in France's centre and the Vosges mountains on the German border, the city was built near its centre, on the youngest rocks. The basement consists of crystalline metamorphic rocks formed during the Variscan/Hercynian orogeny, when America collided with Europe, closing the Iapetus ocean (the first Atlantic) and welding Scotland to the British Isles.
Most of the 3,000 metres of sediments are of marine origin, and we find formations such as the Cretaceous chalk and Jurassic Kimmeridge clay (the source rock for much of the North Sea's oil) that are widespread over Western Europe. From the Triassic to the Jurassic it was an extensional basin, with tectonic forces slowly changing to compression towards the end of the Cretaceous. The most important rocks within the basin for the development of the Earth sciences are the last 150 metres, laid down since the impact that killed the dinosaurs.
Early geologists divided rocks into three categories, first proposed by an Italian called Giovanni Arduino in the 1770's. Primary rocks were the crystalline metamorphic rocks that underlay the later sedimentary rocks. While we now recognise that their ages are highly variable, they were thought to result from one event early in our planet's history. Secondary rocks were the sedimentary strata that were deposited over the basement, and were painstakingly being separated into ages by their different fossiliferous content.
Even then rockhounds recognised that there had been a major turnover in life-forms at the end Cretaceous mass extinction event, and the rocks above this juncture were referred to as tertiary. The untangling of these rocks and their fossils revolutionised our view of the stability of sea levels, and provided crucial evidence in the development of the theory of evolutionThe Tertiary was an era of uplift for these lands that had been submarine for many aeons, related to the slow motion collision of Africa with Europe, that built the Alps and Pyrenees far to the south. The sea advanced and retreated many times, alternating with lagoons and freshwater lakes, each leaving behind sediments with distinctive fossils.
Georges Cuvier was the first to separate out the well preserved Tertiary rocks of the basin into distinct strata based on their fossil content, publishing his work in 1808. He shocked the geological world by stating, based on the alternation of marine and fresh water sediments, that the sea had repeatedly invaded the land, something then thought impossible. Fossils of molluscs that were similar to modern ones provided indisputable evidence of what are now called marine transgressions and regressions, and fossil skeletons of land animals in the freshwater lake sediments made disputing the identification of the mollusc's original environments untenable.
While this idea is a crucial process in modern geology, Cuvier saw it as evidence in the debate between uniformitarians (who followed James Hutton's idea that slow changes like those seen today were responsible for all the world's geology) and catastrophists (who thought cataclysms were the prime mover). France has always been more catastrophist than their rivals across the channel in perfidious Albion, and Cuvier saw the alternations as proof of cataclysmic marine invasions. Each beat of the marine pendulum was recognised to correlate with a turnover in fossils.
In the 1820's , Charles Lyell (who was one of Darwin's geological mentors) noticed that the rocks at the top of the stack had more fossil species that resembled closely those still alive today. He also showed that the further one went back in time (and down the sedimentary stack), the greater the difference in the fossil ecosystems to the present day. He then suggested that older forms had become extinct and replaced somehow by newer ones, often with small incremental changes. He divided the rocks into Pliocene, Miocene and Eocene, names that are still in use today. In the Pliocene rocks 90% of the molluscs were still extant, compared with 18% for the Miocene and 9.5% in the Eocene. Charles Darwin later used his evidence for his theory of evolution by natural selection later in the century.
The younger rocks of the basin include the calcaire grossier, a lovely golden nummlitic limestone cemented by diagenetic silica used in the beautiful buildings of the city. Another famous stratum is a layer of gypsum protected from dissolution by an overlying Eocene clay. It resulted from multiple lagoon evaporation events, and was the main constituent of plaster of Paris, whose uses remain manifold. Oil is pumped in small quantities from parts of the basin, and despite France's ban on fracking, exploration companies entertain hopes for tight oil and gas in the future.
As for the wines, Champagne is grown on the chalk in the east of the basin, and matured within the stable environments of caves within the rock. Imprints of vine leaves 60 million years old have been found in a layer of travertine marble just above the chalk, showing that the tradition of French winemaking exploits a plant that has been endemic to the area for some time. Chablis, a delicious white wine from northern Burgundy with delicious honey overtones is grown on the Jurassic Kimmeridge clay. The next time you sip a glass of either, remember the geology that made them possible, and savour the impact the Paris basin had on our current view of our beautiful planet.
Loz
Image credit: http://newenergyandfuel.com/
cornerstoneminerals
A fossil fern plate from St. Clair, Pennsylvania. This amazing work of natural art is about 300 million years old. Available for $95 shipped, drop us a DM to snag this incredible piece!
The niche of the infaunal filter feeder (sedentary organisms living buried in the mud of the sea floor, surviving on plankton and organic detritus filtered from the water column) is occupied in the modern day by bivalved molluscs - clams, mussels, and similar species - which have a near-universal distribution in all water bodies across the globe. However, this monopoly was not always in place, and before the end of the Permian period, stranger forms were found in the world's oceans. Brachiopods are common as fossils, but few groups remain extant. The brachiopoda existed as a rival phylum to the molluscs from the Cambrian period (540 to 480 million years ago) onwards, reaching a peak of diversity around the Devonian (420 to 360 m.y.a.), but they were decimated during the Permo-Triassic extinction event - 250 m.y.a - (where around 90% of marine species were erased by rapid climate changes), and after that point never regained their strength - bivalves had replaced them by the Jurassic, as their extendable siphon tubes allowed them to bury themselves while retaining contact with clean water above the sediment, thus opening up another niche which helped them to better avoid predation.
Before the Brachiopod period in the Devonian and Carboniferous, an extinct molluscan class came to prominence in the infaunal niche. The rostroconch was a clam-like creature, but its two shells were not hinged like a clam - instead, they were firmly joined at the apex, like a taco shell.
As no living rostroconchs remain, their morphology is mostly a mystery, but it is believed that shell had to be periodically broken into two and 're-set' like a damaged bone, in order to allow the animal to grow.
Rostroconchs were most widespread in the Ordovician (480 to 440 m.y.a.), but declined due to a suspected global ice age (the snowball earth hypothesis) occurring at the end of that period. When the brachiopods came to the fore, they existed for a while in the background, but their class was dispatched completely at the Permo-Triassic boundary.
-TJT
Information on the Rostroconchia is hard to find online, as they have rarely been discussed outside specialist publications. To see some rostroconch fossils, visit http://northtexasfossils.com/rostroconchia2.htm where the beautiful photo of an Apotocardium specimen was found.
Artwork by Franz Anthony / @franzanth
Feather stars like Saccocoma are armed with feather-like appendages surrounding the disc-like body at the center. When the arms find tiny edible particles, they flick it toward the mouth at the center.
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252MYA creates custom-made artwork for private collections and editorial, scientific, or educational projects.
Happy Fossil Friday! Even though this animal looks like a big lizard, it is one of the early relatives of mammals: meet Edaphosaurus! It lived 280 million years ago, in the Permian Period. The key feature that tells us Edaphosaurus is related to mammals? The synapsid opening behind each eye socket. Photo: © AMNH
It’s a Cotylorhynchus Romeri and they fermented their food to digest it. I demand to hear theories for if they were smashfaced drunk all the time or had adapted to the alcohol like Siberian dwarf hamsters.
Final for Koolasuchus cleelandi. In 1978 a jawbone was found in southeastern Australia belonging to a giant amphibian; this in itself was not unusual as amphibians have been found throughout huge swathes of the fossil record, some getting to be downright gigantic among the particular order that this beast belonged to, known as the Temnospondyls.
These creatures were some of the first complex vertebrates to venture on land, doing so as far back as the Carboniferous period and thriving in locations across the Earth throughout the Permian, and into the age of the dinosaurs.
What is interesting is that Koolasuchus was possibly the last of it’s kind, a relic of a bygone era living it’s last days in the Early Cretaceous marking the end of a 210 million year reign. What’s more is that it was an arctic predator, spending it’s time ambushing small dinosaurs and other animals from beneath the bubbling waters of the forest streams that ran through what would later become the region of Victoria, Australia, which was below the Antarctic Circle at the time.
Despite this it’s environment was much more temperate than that of the miles of icy desert found at our southern pole in modern day, while it was cooler by Cretaceous standards, the temperatures had a much warmer global average than they do today.
Koolasuchus cleedandi was officially named in 1997 after paleontologist Lesley Kool (and partially for the “cool” environment it lived in) and geologist Mike Cleeland. Although it has a body similar to that of a modern salamander, it wasn’t exactly a harmless newt, at 16 feet and length and over 1,100 pounds it had a viscous bite and would have been an effective hunter in it’s polar environment, laying in wait like crocodiles do today.
Diplocaulus is an extinct genus of lepospondyl amphibians from the Permian period of North America
Reconstruction by Goro Furuta
Possibly inaccurate as fossil body imprints suggest the presence of flaps of skin connecting the tips of the head with the rest of the body, as in this reconstruction at the University of Michigan:
I’ve never seen dinosaurs displayed in public and the BYU Museum of Paleontology made the wait worth it
The Toroweap formation; an interlude
On top of the stark white cliffs of the Coconino Sandstone there is a more gentle sloping set of beds, where trees and bushes often take root.
At its thickest the Toroweap formation is about 100 meters and it truly is a great example of being “in-between”. At the peak of Pangea’s formation, the seas retreated and the continent dried, forming the giant deserts that are represented by the Coconino Sandstone. After some of the main pulses of mountain-building, the plates on Earth began to reorganize and sea levels again began to rise. The Toroweap formation is a mixture of rock types produced as a consequence of this sea level change. There are sandy layers, layers containing gypsum, shaley layers, and even limestones. This sequence suggests a time when sea levels were rising but occasionally stalling and retreating. The shales and limestones were deposited when sea levels were higher, the sandstones were deposited when they retreated, and salts like gypsum are deposited when ocean water dries up.
The shale layers will erode more easily than the limestones or sandstones, creating patterns of resistant and recessive layers as shown well in this photo.
The Toroweap is about 270-260 million years old, similar in age to the Coconino Sandstone below, so there was likely only a small time interval between the units with limited erosion happening.
-JBB
Image credits: https://www.flickr.com/photos/jsjgeology/8412989402 https://www.flickr.com/photos/grand_canyon_nps/7706161852
Read more: http://3dparks.wr.usgs.gov/coloradoplateau/lexicon/toroweap.htm http://www.grandcanyonnaturalhistory.com/pages_nature/geology/2-toroweap.html http://www.bobspixels.com/kaibab.org/geology/gc_layer.htm#cs
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