CAMBRIAN GEOLOGY AND PALEONTOLOGY
II
ABRUPT APPEARANCE OF THE CAMBRIAN FAUNA ON
THE NORTH AMERICAN CONTINENT[1]
By CHARLES D. WALCOTT
(With One Map)
CONTENTS
| PAGE | ||
| Introduction | 1 | |
| Pre-Cambrian rocks | 3 | |
| Sources of sediments | 5 | |
| Origin of later Algonkian rocks | 6 | |
| Pre-Cambrian Continental Surface | 9 | |
| Unconformity between Cambrian and pre-Cambrian | 11 | |
| Extent of withdrawal of Seas in Late Algonkian Time | 12 | |
| Evidence of Fossils | 13 | |
| Résumé | 14 | |
| Bibliography | 15 | |
ILLUSTRATIONS
| Plate 1. | Map showing distribution of pre-Cambrian Rocks | 4 |
| Fig. 1. | Theoretical profile of North American continent during later part of Algonkian time | 10 |
INTRODUCTION
In accepting the invitation of the Representatives for Paleontology of the Swedish Committee of the Eleventh International Geological Congress, to take part in the discussion of "The Abrupt Appearance of the Cambrian Fauna," I decided to confine the geological discussion mainly to phenomena observed on the North American Continent and to limit paleontological conclusions to results obtained from studies of material from the oldest fossiliferous Cambrian rocks.
In summing up the Lower Cambrian fauna in 1891 [Walcott,
- ↑ Read at the Eleventh International Geological Congress, Stockholm, Sweden, August 18, 1910.
Smithsonian Miscellaneous Collections Vol. 57, No. 1
