Rockhounding Schull's Quarry in Oconto County. One of the locations in WI to find ancient fossils such as this Stromatolite @ 465 million years old formed from shallow seas which covered a large portion of Wisconsin after one of the break-ups of Pangea into Gondwana. Wisconsin back then was just south of the Equator and the environment was lush and tropical terrain.
What was The Ordovician Period?
:idea: 490 to 443 Million Years Ago
The Ordovician period began approximately 510 million years ago, with the end of the Cambrian, and then ended around 445 million years ago, with the beginning of the Silurian Era. At this time, the area north of the tropics was almost entirely ocean, and most of the world's land was collected into the southern super-continent Gondwana. Throughout the Ordovician, Gondwana shifted towards the South Pole and much of it was submerged underwater.
universe-review.ca/option2.htm
The Ordovician is best known for the presence of its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts ( or early vertebrates). A typical marine community consisted of these animals, plus red and green algae Stromatolite, primitive fish, cephalopods, corals, crinoids, and gastropods. More recently, there has been found evidence of tetrahedral spores that are similar to those of primitive land plants, suggesting that plants invaded the land at this time.
From the Early to Middle Ordovician, the earth experienced a milder climate in which the weather was warm and the atmosphere contained a lot of moisture. However, when Gondwana finally settled on the South Pole during the Late Ordovician, massive glaciers formed causing shallow seas to drain and sea levels to drop. This likely caused the mass extinctions that characterize the end of the Ordovician, in which 60% of all marine invertebrate genera and 25% of all families went extinct.
My parents represented in Rockhound Attire. Actually my sister discovered one of the largest specimens of the Stromatolite, which could be moved out of the Quarry weight: 340lbs value priceless to us but valuable to the Geologist within our Group who wanted the piece for the Weis Museum in Appleton. Interested in this fossil it’s now a permanent fossil within my parents rock garden backyard.
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