INTRODUCTION 



Preface 



The rapid growth of population accompanied by expansion of industrial and agricultural 

 activities on Long Island during the past 25 years has resulted in the drilling of large numbers 

 of wells for public supply, air-conditioning, industrial, and agricultural purposes. 



The increased usage of ground water has raised many serious problems with regard to the 

 conservation and protection of present supplies. Intrusion of salt water into water-bearing beds 

 along the shore lines, the lowering of water levels in certain localities due to over-pumping, 

 •and estimation of the safe yields of the aquifers are some of the problems which are confront- 

 ing Federal, State, County, and municipal agencies concerned with the proper development of 

 the ground-water resources of Long Island. 



All of these problems require intensive Island-wide studies of the geologic and hydrologic 

 factors affecting the occurrence and movement of ground water. This report deals with the 

 geologic phase, and includes information as to the distribution, geologic structure, and thick- 

 ness of the unconsolidated deposits on Long Island. It also contains information as to areas of 

 recharge of the various aquifers, the nature of the various confining beds, and the physical 

 properties of the sediments of which the aquifers are composed. 



The geologic work which forms the basis of this report and the following report by Wallace 

 de Laguna was performed under the supervision of M. L. Brashears, Jr., District Geologist for 

 New York and New England for the Geological Survey, and was carried on in financial coopera- 

 tion with the New York State Water Power and Control Commission whose work on this proj- 

 ect was directed by Mr. Russell Suter, Consulting Engineer, and formerly Executive Engineer 

 for the Water Power and Control Commission. Much assistance was furnished by the Nassau 

 County Department of Public Works, the Sufl^olk County Board of Supervisors, and the Suifolk 

 County Water Authority and is here gratefully acknowledged.* 



Previous Investigations 



" Shortly after the completion of the work of the Burr-Hering-Freeman Commission on 

 Additional Water Supply for the City of New York (6), the U. S. Geological Survey in 1906 

 published the first systematic island-wide report, by A. C. Veatch (9) , on the geology and hydrol- 

 ogy of Long Island. This report contains a brief outline of the geology together with geologic 

 correlations for a considerable number of wells drilled prior to 1906, including many of those 

 drilled by the Burr-Hering-Freeman Commission. In 1914, a more detailed geologic report 

 based upon extensive field work by M. L. Fuller, was published by the Geological Survey (15) . 

 W. 0. Crosby also made studies for the Board of Water Supply of the City of New York (11). 

 His report, which contains a number of fundamental geologic differences with the reports of 

 Veatch and Fuller, has never been published. A discussion of some of these differing theories 

 expressed by these investigators, together with a contour map of the buried pre-Pleistocene sur- 

 face of Long Island, based upon information available at that time, is contained in a technical 

 paper published in 1937 (27) . 



''Compiler's Note. It is understood that the official scientific name of the youngest of the Cretaceous strata 

 is Magothy (?). This symbol is all very well as indicating that the stratum on Long Island may not be the 

 same as the Magothy stratum in New Jersey. It is, however, an awkward symbol as written and particularly 

 awkward in that it cannot be easily expressed in words, either in dictation or in conversation. Therefore, in the 

 geologic report the authors have not always been consistent and have frequently used the term Magothy with- 

 out the question mark. 



