LOWER SILURIAN SYSTEM OF EASTERN MONT- 

 GOMERY COUNTY, NEW YORK 



BY 



E. R. CUMIXGSi 



Representatives of all the rocks of the typical American lower 

 Silurian system, with the exception of the Chazy stage, may be seen 

 within a radius of five miles of Amsterdam^ in the eastern part of 

 Montgomery county, New York. The city of Amsterdam is sit- 

 uated on the easternmost of the series of uplifts that intersect the 

 valley of the Mohawk river between Hoffman ferry and Littlefalls, 

 all of which have thrust the lower rocks of the system through the 

 upper. The present paper deals wdth the lower Silurian system as 

 developed in the vicinity of Amsterdam in Perth^ Amsterdam and 

 Florida townships of Montgomery county, and Charlton, Glenville, 

 Rotterdam, Princetown and Duanesburg townships of Schenectady 

 county. In order that the following part of the paper may be less 

 cumbered with footnotes^ a brief historic sketch and description of 

 the system is here given in the following order: 



Historical sketch and review of previous work 



Calcif erous sandrock. In his report on the Geological and agricul- 

 tural survey of the district adjoining the Erie canal (1824) Prof. Eaton 

 named the Calciferous sandrock, describing it as "an 

 aggregate of quartzose sand and fine grains of carbonate of lime. . . 

 The quartz is generally in the largest proportion" (p. 32, 33). He 

 states in another place that " the most perfect locality as well as 

 the most accessible to those who travel the canal is Flint hill in 

 Florida township and its continuation two or three miles west. In 

 this locality we find dark brown and pearly hornstone, brown and 



^This thesis was submitted by Mr Cumings for honors in geology which were granted 

 him by the faculty of Union college in June 1897. The accompanying geologic map 

 of the Amsterdam sheet is the result of the work of Messrs Prosser, Cumings and 

 Fisher.— C. 8. Prosser 



-Where volume and page references are given, the numbers are separated by a 

 colon; e. g. 3:21 means volume 3, page 21. Where reference is to " part ", pt 2, p. 401 

 is the form used. 



