A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region

A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region

A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region

A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region

Synopsis

The region around Cincinnati, Ohio, is known throughout the world for the abundant and beautiful fossils found in limestones and shales that were deposited as sediments on the sea floor during the Ordovician Period, about 450 million years ago--some 250 million years before the dinosaurs lived. In Ordovician time, the shallow sea that covered much of what is now the North American continent teemed with marine life. The Cincinnati area has yielded some of the world's most abundant and best-preserved fossils of invertebrate animals such as trilobites, bryozoans, brachiopods, molluscs, echinoderms, and graptolites. So famous are the Ordovician fossils and rocks of the Cincinnati region that geologists use the term "Cincinnatian" for strata of the same age all over North America. This book synthesizes more than 150 years of research on this fossil treasure-trove, describing and illustrating the fossils, the life habits of the animals represented, their communities, and living relatives, as well as the nature of the rock strata in which they are found and the environmental conditions of the ancient sea.

Excerpt

Two principal goals motivated us to write this book. First, knowledge of the Earth’s ancient history from geology provides a powerful lesson about the ever-changing nature of the planet, and the ancient history of one’s home region can be particularly meaningful. the present nature of the landscape in the Cincinnati region (southwestern Ohio, northern Kentucky, and southeastern Indiana) is the product of its most recent geologic history, the Pleistocene Ice Age, when continental ice sheets repeatedly forced their way as far south as the Ohio River. As recently as 20,000 years ago, much of southwestern Ohio was covered with an ice sheet much as Greenland is today. As the glaciers receded, melt waters carved the present valleys and left a mantle of debris that determined the topography, drainage, soils, and vegetation of the region. a magnificent Ice Age exhibit at the Cincinnati Museum Center enhances public awareness of the profound environmental changes that took place across the region in the short time span in which humans inhabited the ice-free land. Three works also provide a concise history of the environmental changes during the Ice Age: Richard H. Durrell’s A Recycled Landscape (1977), Richard Arnold Davis’s “Land Fit for a Queen: the Geology of Cincinnati” (1981), and the recently published Natural History of the Cincinnati Region, by Stanley Hedeen (2006).

As impressive as the Ice Age history of the region is as evidence of geologic and climatic change, the story that can be told from the ancient bedrock underlying the Pleistocene cover extends the record of global change into deep time. the bedrock exposed at the surface across southwestern Ohio, northern Kentucky, and southeastern Indiana is the record of the Ordovician sea of some 450,000,000 years ago, one of the most extensive marine flooding intervals of the North American continent during Earth history. in stark contrast to the barren ice sheet of the Pleistocene, the Cincinnati seascape of the Ordovician was water from horizon to horizon—not a deep ocean blue, but perhaps shades of aquamarine like the waters over the present-day shallow Great Bahama Bank. No landmasses broke the horizon, and no birds crossed the skies. All the action was beneath the sea surface, where life thrived in abundance. This profusion of life left a fossil record in the rocks that formed from the bottom sediments of the Cincinnatian sea that is among the world’s richest treasure troves of the past. For present-day Cincinnatians, fossils in their backyards are a commonplace, and many natives grow up not realizing that most of the rest of the world has nothing to rival the fossil riches of their home! We seek to recount the history of the Cincinnati region in deep time, its vastly different environment and marine life, for the general public and for amateur geologists.

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