BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 17, PP. 29-64, PLS. 12-23 MAY 25, 1906 



RECENT CHANGES OF LEVEL IX THE YAKUTAT BAY 



REGION, ALASKA* 



BY RALPH S. TARR AND LAWRENCE MARTIN 



{Read before the Society December 28, 1905) 



CONTENTS 



Page 



Introductory considerations 30 



Earthquake of September, 1890 30 



Location and general physiography 32 



Geological structure 33 



Previous explorations 34 



General statement of observations in 1905 35 



Physiographic evidences of recent uplift 35 



Elevated rock benches 35 



Elevated sea caves and chasms 36 



Elevated beaches 37 



Elevated alluvial fans, or deltas 38 



Till shorelines 38 



New reefs and islands 39 



Amount of land added by uplift 40 



Biological evidences of uplift 40 



Barnacles 40 



Mussels 41 



Bryozoans 41 



Other marine organisms 42 



Mingling of land and sea life 42 



Parallel lines of driftwood 43 



Destruction of life 43 



Human evidence of uplift 44 



General evidence of recency 44 



Negative evidence of the Harriman expedition 44 



♦The observations recorded in this paper were made in the summer of ]00r>. in con- 

 nection with a general geological study of the Yakutat Bay region by a United States 

 Geological Survey party under the direction of the senior author. A grant of money 

 obtained through the assistance of the American Geographical Society made it possible 

 to add the junior author to the party as special assistant in physiographic and glacial 

 geology. Acknowledgments are due to B. S. Butler, the other member of the scientific 

 corps, for assistance in this work. 



The paper is published by permission of the Director of the United States Geological 

 Survey. 



V — Bull. Geol. Soc. Am., Vol. 17. 1905 (29) 



