GLACIAL GEOLOGY OF THE SARATOGA QUADRANGLE 43 



When at length Lake Albany had subsided to the 320 foot level, 

 thus causing the Saratoga plain to emerge as land, Kayaderosseras 

 creek began to flow across the surface of this added area. Coursing 

 northeastward from Ballston Spa the stream, still of considerable 

 magnitude and of powerful currents, swept away the sands from a 

 broad path, laying bare the underlying till, and discharging into 

 the shrunken Lake Albany. At a later time when conditions of 

 comparatively quiet waters had ensued the stream began to aggrade 

 its channel and the deposits of alluvial character, forming the broad 

 area of valley flats, through which the creek now pursues a meander- 

 ing course, were laid down. 



Another stream whose origin was incident to the subsidence of 

 Lake Albany is Coesa creek (unnamed on the map) which gathers 

 its waters from sources in the highlands north of Saratoga Springs 

 and from the Greenfield hills and flows southeasterly emptying into 

 the Kayaderosseras. The stream, with its branches, has cut broad 

 trenches in the expanse of the Saratoga plain and where it passes 

 over the slope, bounding the depressed area, has cut into the rocks 

 forming a gorge. The western branch of Coesa creek, taking its 

 rise near North Milton, has lowered its bed to rock, exposing the 

 limestone at the site of the old stone mill, i l / 2 miles east of North 

 Milton. The erosive work of these streams was largely accom- 

 plished in late glacial or early postglacial times, accompanying the 

 subsidence of Lake Albany. 



A notable event in the late glacial history of the Mohawk-Hudson 

 region, also incident to the subsidence of Lake Albany, was the 

 diversion of powerful currents from the flooded Mohawk north- 

 ward through the Ballston channel. 1 Waters from this source, 

 following the courses indicated by the present streams, Mourning 

 kill and Drummond creek, swept across the southeastern portion of 

 the Saratoga quadrangle, removing from their path the Lake Albany 

 deposits, and leaving the areas of eroded till now forming the sur- 

 face materials in that quarter. 



RECENT DEPOSITS 

 Alluvium. Reference has been made above to the extensive flats 

 bordering Kayaderosseras creek, especially in the neighborhood of 

 Kings and in the depressed area east of Ballston Spa. It is prob- 

 able that these flats represent in part alluvial deposits of the recent 

 epoch, that is, sediments laid down by the stream at high water 



iStoller. N. Y. State Mus. Bui. 154, p. 31. 



