254 ROCHESTER ACADEMY OF SCIENCE 



steep cliffs of the river gorge. Dr. John M. Clarke has referred 

 to this work of Gilbert (in Science, volume 10, 1899, page 695) 

 as the first attempt of the kind ever made. The field work was 

 done in 1866, when Gilbert was only 23 years of age, although the 

 paper may have been completed a couple of years later. It is a fine 

 example of Gilbert's philosophic method and of his ability. 



In 1869 he began, on the Ohio Geological Survey, under Professor 

 y. S. Newberry, his geologic work. That this work was deliberate 

 choice appears from the "Historical Sketch" by Newberry, in 

 the report for 1869 (page 9), where we read: 



"Of the other members of the corps, Messrs. Gilbert and Sherwood were 

 geologists who had devoted much time to practical geology in New York 

 and Pennsylvania, and who, for the purpose of adding to their experience, 

 volunteered their services for no other compensation than their traveling 

 expenses." 



In the report for 1870 Dr. Newberry writes : 



"The fossil fishes and fossil plants found in the state have been described 

 by myself. They have been drawn by Mr. T. Y. Garner and Mr. G. K. Gil- 

 bert in a style that has not been surpassed in this country, and some of 

 their work is equal to any of a similar character done by the best European 

 draughtsmen" (page 8). 



This volume contains a short report by Gilbert on three counties 

 in the northwestern part of the state. A fuller report on the same 

 district is attached to a report on the surface geology of the Maumee 

 Valley, found in Volume 1, of the final reports of the Newberry 

 survey. This writing, published in 1873, contains six maps, evi- 

 dently all his own work. The first two maps show the beaches 

 of the ancient glacial waters in the Maumee Valley, and the cor- 

 relation of the highest shore with the pass at Fort Wayne. 



These fine maps are the first ever made in delineation of ancient 

 lake beaches and correlation with the controlling outlet. The field 

 work for this report was done in 1869 and 1870, when he was only 

 twenty-seven years of age. At this time Gilbert did not recognize 

 the receding ice sheet as the dam that held up the ancient waters, 

 but he did clearly postulate deformation of the earth's surface as 

 one cause of the variation of levels. He says (page 551) : 



