NEW FACTS AND REDISCUSSION 519 



vened, the currents forced their way through the new area of delta de- 

 posits, producing the watercourses above mentioned. 



MALTA DELTA STAGE 



The delta deposits marking the first stage of subsidence of Lake Albany 

 are now represented by areas of sand, or of predominantly sandy compo- 

 sition, having the topographic forms of sand-plains or of terraces border- 

 ing the watercourses above referred to. The original delta was spread 

 over the whole region of country (excepting those portions which stood 

 above the level of the lake waters) east of Ballston Spa to beyond the 

 southern end of Saratoga Lake and southeastward over the area sur- 

 rounding the Eound Lake depression. The plain on which the village 

 of Malta is located was the central portion of the area of deposition, and 

 the general delta, developed at this stage in the subsidence of the lake, 

 may be named the Malta delta. 



The elevation of these sand areas does not vary much from 360 feet. 

 The fact that the Malta delta now has approximately the same elevation 

 above sea as the Schenectady delta is undoubtedly explained by post- 

 glacial northward uplift. As previously reported by the writer, there is 

 evidence that this differential uplift has been about 2% feet to the mile in 

 the Schenectady-Saratoga region. 7 It may be considered, therefore, that 

 the Malta delta originally stood at a level some 30 feet lower than now; 

 in other words, that it was built into Lake Albany when that body of 

 water had subsided about 30 feet from the level of its waters at the maxi- 

 mum stage of development of the lake. 



With the lowering of the lake waters to a level below that of the general 

 surface of the Malta delta, the Iroquois-Mohawk currents, as above stated, 

 forced their way through the deposits, breaking into several distributaries, 

 thus originating the watercourses above described and leaving the present 

 areas of sand-plains as remnants of the original delta. 



SARATOGA DELTA STAGE 



With the close of the second stage of subsidence of the Lake Albany 

 waters another period of delta-building began. The delta marking this 

 interval of a fixed level of the lake waters is represented by the sand- 

 plain on which the greater portion of the village of Saratoga Springs is 

 built and which stretches west, south, east, and northeast from that lo- 

 cality. The general level of this plain is 320 feet. That it originally 

 extended farther to the south is shown by the occurrence of an isolated 



7 J. H. Stoller : N. Y. State Mus. Bull. No. 183, p. 38. 



