Definition
GEOLOGIC COLUMN: A division of rocks in the earth's crust by age according to the fossils they contain.
The following statements are TRUE:
Geologic time is divided into four major divisions called Eras!
The Precambrian Era began about 4.5 billion years ago!
The early Precambrian Era is characterized by much cratering on the Earth's surface from collisions with many smaller objects (accretion)!
The Earth's core began to form about 4 billion years ago with an event called the Iron Catastrophe!
The Cambrian Explosion was a proliferation of life forms that marked the beginning of the Paleozoic Era!
The early Paleozoic Era was characterized by a large variety of simple life forms (worms, trilobites, sponges, corals, etc.!
The Paleozoic Era began about 570 million years ago!
The Eras of the Geologic Column are subdivided into Periods and the Periods are subdivided into Epochs!
Mammal-like reptiles first appeared in the rock layers of the late Paleozoic Era!
The end of the Paleozoic Era is marked by a great extinction of life (called the First Great Dying)!
Dinosaurs lived during the Mesozoic Era!
The end of the Mesozoic Era is marked by a great extinction of life (called the Second Great Dying)!
Mammals and flowering plants are characteristic life forms of the Cenezoic Era!
The Great Ice Age (actually the last of several in a row) occurred in the latter part of the Cenezoic Era!
The supercontinent Pangaea split apart during the Mesozoic Era!
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