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The work described in this paper was all done in connection with dam‐site investigations and was not directly connected with hydrology. However, geophysics is coming to have a place in hydrologic investigations, and these results may throw some light on what can be accomplished by resistivity‐measurements.We have found that,for many questions not involving exact determinations of depth, resistivit

The modern deep well makes it possible to determine the temperatures of the rocks to depths exceeding two miles, and the rock‐samples obtained at these great depths enable the geologist to estimate the depths to the deeply buried basement‐rocks to a rather high degree of precision. The latter estimates are now being supplemented to a certain extent by the precision‐measurements of geophysicist, so

Recent studies have shown that relatively impermeable clay beds are widespread on Long Island but that erosion channels cutting through them permit restricted recharge of the underlying beds in some parts of the island. Of the more than 200,000,000 gallons of water a day now pumped from wells, about 65 per cent. comes from the surficial beds of Illinoian or Wisconsin age. Because of the restricted

In the past five years members of the Geological Survey have gained experience in making isometric block diagrams of mines and mining districts as well as of surface features. This paper presents nothing new, but aims to assemble scattered information on a much neglected method of geological illustration. Plotting mine workings on isometric paper is the usual method but is extremely time-consuming

Some of the recent floods in the United States have indicated that, in any appraisal of the potentialities of a river system for producing floods, more significance than has perhaps been customary should be attached to the magnitude of the great floods of the past, as disclosed by Nature's records of them. A conspicuous part of the work of rivers in the processes of dynamic geology is associated w

The La Plata Mountains, in southwestern Colorado, have long been known as an example of a mountain group of the laccolithic type, although it has been recognized that the igneous geology was much more complex than that of typical laccoliths. A restudy of the ore‐deposits of the District, now in progress, has thrown new light on the mode of intrusion of the igneous rocks (E. B. Eckel, Resurvey of t

A series, of 11 cores from the North Atlantic sea‐bottom between the Newfoundland Banks and the banks off the Irish Coast have been studied by a group of geologists of the United States Geological Survey. These cores were taken by Dr. C. S. Piggot of the Carnegie Institution's Geophysical Laboratory from the cable ship Lord Kelvin with the explosive type of sounding‐apparatus, which he designed (C

The Chelmsford granite is quarried in and around Oak Hill, about six miles west of Lowell, Massachusetts. The granite‐area is about eight miles long and one to three miles wide, and its longer dimension has a northeast bearing which is parallel with the regional axis of foliation in the country rock. The writer favors a hypothesis that much of the granite represents granitization of biotite schist

No abstract available.

The banded fluorspar deposits of the Cave In Rock district are attributed to replacement of limestone and the preservation of bedding and cross-bedding of the rock. The solutions contained hydrofluoric acid which reacted with CaCO 3 . The replacement was stoichiometrical, with consequent reduction of volume, but continued deposition of calcium fluoride, brought in from other points, partly or comp

No abstract available.

No abstract available.