TABLES OF TENTATIVE GEOLOGIC CORRELATIONS OF 

 WELL LOGS IN LONG JSLAND. NEW YORK 



NOTES 



Caution: The reader must keep in mind that all the figures shown, indicate feet above or 

 below sea level, unlike the well logs from which they are derived, where all measurements are 

 made downward from some point at or near the land surface. The first figure in the column 

 headed "Recent and Upper Pleistocene" is the elevation of the land surface. 



Wells included: In general, a correlation has been attempted for every well log published 

 in the "Records of Wells" bulletins published jointly by the New York State Water Power 

 and Control Commission and the U. S. Geological Survey. Also included are a small number 

 of wells taken from U. S. Geological Survey Professional Paper 44, 1906 and some previously 

 unpublished records of recent wells from the files of the New York State Water Power and 

 Control Commission. 



Map coordinates: The map coordinates refer to the five minute grid square in which the 

 well is located. These squares coincide with the lines of latitude and longitude printed on the 

 U. S. Geological Survey 1:62500 topographic maps for Long Island, although the method of 

 designation has been changed on the accompanying maps. Where the coordinates are followed 

 by an asterisk (*) , that well number does not appear on the map, as where there is more than 

 one well at the same location, only the number of the deepest well or the well having the most 

 satisfactory log is shown. 



Total depth: The total depth, in feet, is calculated from the land surface, regardless of the 

 measuring point used for the published log. The bottom is taken as the lowest point described 

 in the well log, and this figure is underlined in the tables. 



Recent and upper Pleistocene: This column includes all the Recent and youngest glacial 

 deposits, measured downward from the land surface to the top of the Gardiners clay, the 

 surface of the bedrock or the top of the Cretaceous beds. 



Reliability of correlation: The tables are based on the assumption that the driller in each 

 case has accurately reported the nature and depth of the beds penetrated. The notations 

 "good", "fair" or "poor" indicates the confidence of the geologist in his interpretation of the 

 record. Question marks indicate that the boundaries or existence of a formation are uncertain. 

 For a description of the geologic units and a discussion of the geology of the area, the reader 

 is referred to the accompanying text. 



Abbreviations used in column "Aquifer Developed"— 

 U.P. — Upper Pleistocene 

 G — Gardiners Clay 

 J — Jameco gravel 

 M — Magothy (?) formation 

 BM — Basal Magothy (?) gravel 

 R — Raritan foi-mation — clay member 

 L — Raritan formation — Lloyd sand member 

 Br — Bedrock 



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