Reviews 



Geology of Saratoga Springs and Vicinity. By H. P. Cushing and 

 R. Ruedemann. New York State Museum; Bull. No. 169, 

 1914. Pp. 177, pis. 20, figs. 17, maps 2. 



Scientific interest regarding Saratoga Springs and vicinity centers 

 about its mineral waters, and this report has been published in response 

 to a demand for detailed information on local geological conditions. 



Rocks of Pre-Cambrian, Cambrian, and Ordovician age outcrop 

 in the area. The Paleozoic rocks are divided into deposits of eastern 

 and western troughs, characterized by different sets of formations. The 

 western trough was being eroded in Lower Cambrian times, but in the 

 east the Georgian is the only Cambrian present. The rocks of the 

 western division are horizontal or nearly so, but in the east the beds are 

 intensely folded and crumpled. Two great normal faults with a number 

 of branches cross the Saratoga quadrangle. These are known to be 

 genetically connected with many of the mineral springs. 



A unique feature is the Northumberland volcanic plug. It outcrops 

 just north of Schuylerville as a knob of extrusive rock and is unlike any 

 other igneous rock in the state. It has been connected with one theory 

 for the origin of the mineral springs, but unfortunately the authors were 

 unable to determine with certainty whether the rock is in place or not, 

 and are in doubt in regard to calling it a volcanic neck or a fragment of 

 a surface flow. 



It was planned to have Professor Kemp write a chapter for this 

 bulletin on the origin of the mineral waters but his results were published 

 in an earlier report. The authors are not convinced that Kemp's con- 

 clusions are justified by the field evidence. Kemp holds that the mineral 

 waters, in part at least, are of magmatic origin. He cites as proofs their 

 local occurrence, the volcanic neck, the large amount of free C0 2 , and 

 the almost complete absence of sulphates. The authors believe that 

 the absence of carbonated waters to the north is due to lack of shale 

 covering and resulting dilution with surface waters. They hold that 

 the volcanic knob furnishes no evidence of igneous activity of sufficient 

 recency to justify connecting it with present-day juvenile waters. The 

 abundant C0 2 may come from deeply buried impure limestones and 



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