74 BULLETIN OF THE ESSEX INSTITUTE. 



deposition from subglacial streams discharging their load 

 of sand and gravel below sea-level. The creases are ex- 

 plained as due to initial shaping by the outrunning streams 

 and to subsequent modification by the to-and-fro move- 

 ment of tides. The depth of water, not definitely de- 

 termined, is thought to have been us great as 300 feet. 



1889. Professor Shaler,i in this year, published a 

 report on the Geology of Nantucket, in which he describes 

 the outwash plain of that island, notes its surface features, 

 including the creases, and discusses the relations of the 

 head of the plain or terrace to the currents which deposited 

 the detritus in the plain. 



1890. Professor Davis, ^ in a paper " On the Struct- 

 ure and Origin of Glacial Sand-plains," gives a critical 

 study of an esker-fan near Newtonville, Mass. 



1891. Mr. Upham,3 in a paper entitled " Walden, Co- 

 chituate and other lakes, enclosed by modified drift, "de- 

 scribes certain ice-block holes in this area. 



1892. Professor Davis, ^ in a paper " On the Subglacial 

 Origin of certain Eskers," considers sand-plateaus as del- 

 tas marginal to the ice-sheet. 



1893. Professor Davis, ^ in a publication entitled "Geo- 

 graphical Illustrations," notes the occurrence knd influence 

 of numerous sand-plains on settlement in this district. 



1893. Dr. F. P. Gullivers describes a model based 

 upon the esker-fan at Newtonville previously described 

 by Professor Davis. A second model is introduced to 

 show supposed relations of the ice-front to the delta. 



1 Bulletin 63, U. S. Geol. Survey. 



2 Bull. Geol. Soc. Ainer., vol. 1, pp. 195-202, pi. 3. 



3 Proc. Boston Soc. Nat. Hist. vol. xxv, pp. 228-242. 

 *Proc. Boston Soc. Nat. Hist. vol. XXV, lS92,pp. 47"-4!»9. 



* Geographical Pu))lications. Published hy Harvard University, Cambridge, 

 Mass., 1893, pp. 4R. Reprinted from the Proceedings of the Am. Institute of In- 

 struction, 1892. 



• The [Chicago] Journal of Geology, vol. 1, 1893, pp. 803-812. 



