Question

The first continental red beds were deposited during the ________ eon, and passive continental margins became common during the ________ eon.

Answer 1

Proterozoic, Proterozoic

Step-by-step explanation:

The proterozoic eon is the younger of the two divisions of Precambrian time. The older if the two is the Archean eon. The Proterozoic Eon is a period from 2.5 billion to 541 million years ago and is often divided into the Paleoproterozoic era, the Mesoproterozoic era and

Neoproterozoic eras. Proterozoic rocks important sources of metallic ores, such as iron, gold, copper, uranium, and nickel.

During this time, the atmosphere and oceans changed significantly and caused developments such as high increase in oxygen.

Proterozoic rocks are evidence of many primitive life-forms such as bacteria and the Ediacara fauna.