Excerpt from Changes in Stratigraphic Nomenclature by the U. S. Geological Survey, 1972 The scheme of subdivisions has been devised simply to facilitate depiction and analysis of the Precambrian history of the United States. The time boundaries have been chosen so as to split as few of the known epochs of sedimentation, orogeny, and plutonism as possible. The boundaries do not correspond intentionally to geo logic events. The scheme is intended as an interim measure, pend ing development of an internationally accepted standard. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Excerpt from Changes in Stratigraphic Nomenclature by the U. S. Geological Survey, 1975 In the following table, stratigraphic names adopted, revised, reinstated, or abandoned are listed alphabetically. The age of the unit, the revision, and the area involved, along with the author's name and date of publication of the report, are given. The publica tions in which the changes in nomenclature were made are listed in the references at the end of this publication. The capitalization of age terms in the age column follows official usage. The following formal designations of Precambrian time are now in use by the u.s. Geological Survey. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

The United States Geological Survey (USGS) is a scientific organization created in 1879, and is part of the U.S. government. Their scientists explore our environment and ecosystems, to determine the natural dangers we are facing. The agency has over 10,000 employees that collect, monitor, and analyze data so that they have a better understanding of our problems. The USGS is dedicated to provide reliable, investigated information to enhance and protect our quality of life. This is one of their bulletins.