The rocks highlighted here are the youngest in the United States. They formed in the Quaternary Period, between 1.6 million years ago and the present. The Quaternary Period is the youngest division of the Cenozoic Era. It is divided into two epochs; the Pleistocene and the Holocene. The Pleistocene, from 1.6 million years ago to 11,000 years ago, saw the evolution of human beings. The end of the Pleistocene is marked by the last of the great Ice Ages. The Holocene refers to the 11,000 years leading up to and including the present. We are living in Holocene time!
The geologic features from this time period include the results
of recent volcanic activity, such as Crater
Lake, Valles Caldera,
and The Snake River Plain,
as well as recently deposited sediments, like The
Mississippi Delta and The
Central Valley of California.
Quaternary features of the United States:
Volcanic Features
Glacial Features
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Sedimentary Features
Ongoing Tectonics
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