GEOLOGY OF THE BROADALBIN QUADRANGLE 7 



The largest south flowing stream is Chuctanunda creek which 

 reaches the Mohawk at Amsterdam. 



Geologically considered the district shows a great variety of rock 

 formations and structures. The highlands of the north consist of 

 rocks which belong to the oldest (Precambric) known formations 

 of New York State. They comprise very ancient sediments and 

 igneous rocks which have been profoundly changed from their origi- 

 nal condition. No less than four distinct types of these rocks have 

 been recognized within the quadrangle. 



Another great set of formations younger in age and resting upon 

 the Precambric belongs to the Paleozoic system. All the lowlands 

 of the district are occupied by these formations which are ancient 

 sediments such as limestones, sandstones and shales and which have 

 not been greatly changed from their original condition. 



The most recent deposits of the quadrangle are of Pleistocene 

 age.^ They are vastly younger than the Paleozoics and include the 

 most recent deposits of the earth. They are merely superficial de- 

 posits of sand, gravel and clay irregularly scattered over the country 

 and were formed either during or after the Glacial epoch (Ice age) 

 when New York was buried under a great sheet of ice. 



The structure or arrangement of the rock masses has been very 

 noticeably affected by displacements or faulting of the earth's crust. 

 The quadrangle is unusual for its number of faults, no less than 

 fourteen with considerable displacement having been located. The 

 most prominent topographic features of the quadrangle are due to 

 faulting as, for example, the steep fronts of the highland masses 

 already described.^ 



lA chapter on the Pleistocene (glacial) geology of the quadrangle has 

 not been included in this bulletin because Professor Brigham, who has 

 carefully studied the glacial history of this and the neighboring Gloversville, 

 Amsterdam, and Fonda sheets, has already presented a brief report (see 

 paper below cited) and a more elaborate account will soon be forthcoming. 



^ The following list comprises the principal papers having a bearing upon 

 the geology of the quadrangle: 



1823. Steele. Geology of Saratoga Co. Mem. Board Agric. State N. Y. 

 Vol. 2. 



1842. Vanuxem. Geology of the 3rd Dist. N. Y. 



1843. Mather. Geology of the ist Dist. N. Y. 



1893.^ Darton. Geology of the Mohawk Valley, 13th An. Kept. N. Y. State 

 Geologist. 



1894. Darton. Faulted Region of Herkimer, Fulton, Montgomery, and 

 Saratoga Counties. 14th An. Rept. N. Y. State Geologist. 



1899. Kemp & Hill. Precambric Formation in parts of Warren, Sara- 

 toga, Fulton, and Montgomery Counties. 19th An. Rcpt. N. Y. State Geol- 

 ogist. 



1900. Cumings. Lower Silurian System of Eastern Montgomery Co. N. Y. 

 State Mus. Bui. 34. 



