GEOLOGY OF SARATOGA SPRINGS AND \'ICI.\ITV ^i 



i*aleozoic formations. The western trough, which has been called 

 the Chazy basin, was a subsiding trough which repeatedly was sub- 

 merged beneath sea level during the early Paleozoic and received 

 marine deposits, whose uneroded remnants still lie in comparatively 

 undisturbed condition where they were deposited. In one or more 

 troughs which lay farther to the east and were mostly quite sepa- 

 rate from the Chazy basin, early Paleozoic deposits were also 

 formed. These have since been greatly folded and faulted, and 

 bodily overthrust to the west from their original position, upon the 

 rocks of the Chazy basin. For convenience we here refer to them 

 as the deposits of the eastern trough, without thereby meaning in 

 any way to indicate that we necessarily regard them as deposits 

 of an original single trough, rather than as of more than one. 

 These rocks do not now lie where they were originally deposited 

 and they are much more disturbed and folded than the rocks of 

 the western trough. 



The formations of the western trough, in order of age, are the 

 Potsdam sandstone, Theresa formation, Ployt limestone. Little Falls 

 dolomite. Black River limestones (chiefly the Amsterdam lime- 

 stone), basal Trenton shale and limestone ((liens Falls limestone) 

 and Canajoharie shale. All these, with the exception of the Tren- 

 ton shale and limestone, appear upon the map. 



Surface upon which the western basin rocks were deposited. 

 The old surface of Precambric rocks, upon which the basal por- 

 tion of the Paleozoic deposits rests in Xew York, has been shown 

 by several observers to be an uneven surface, but yet not exces- 

 sively uneven. The data are most easily obtainable on the west, 

 since there the rocks are much less disturbed than on the east. On 

 the southwest both ^filler and Cushing have shown that this sur- 

 face was exceedingly smooth, almost plane, with only a few scat- 

 tered hillocks rising a few feet above the general level. ^ -None 

 have been observed rising higher than 50 feet above this level. On 

 the northwest this surface is far less smooth, and consists of 

 rapidly alternating elevations and depressions, with maximum dif- 

 ferences of some 125 feet of altitude. The surface consists 

 chiefly of slopes, and but little of it is flat.- 



(^n the southeast, in the Saratoga region, the surface seems much 

 as on the northwest. l''or the I'roadalhin (inadrangle Miller rei)orts 



IN. Y. State Mus. Biil. 126, p. 35; N. V. State Mus. lUil. 77, p. 50-62. 

 - N. Y. State Mus. Rul. 145. p. 54-60. 



