Part 13

Note: Bulletins of the U.S.G.S. are purchasable from the Superintendent of Documents, Washington, D. C. Maps are sold by the Director of the Geological Survey, Washington, D. C.

Transcriber’s Notes

—Silently corrected a few typos

—Restored one accidental omission in the Table of Illustrations

—Retained publication information from the printed edition: this eBook is public-domain in the country of publication.

—In the text versions only, text in italics is delimited by underscores.