INTERNAL STRUCTURE OF GRANITIC PEGMATITES.
By E. N. Cameron, University of Wisconsin, R. H. Jahns, California Institute of Technology, A. H. McNair,Dartmouth College, L. R. Page '30, U. S.Geological Survey. Monograph 2. EconomicGeology Publishing Co., Urbana, Illinois.Price, $4.00.
This monograph is recommended reading for those alumni who have made geology their profession, and is of interest to many more in that it is the result of a combined effort by many scientists, a very large number of them Dartmouth men, to record and interpret the geology of pegmatites, a special sort of ore deposit.
The monograph deals with pegmatites which are dike-like masses of coarse grained igneous rock composed of the minerals quartz, mica and feldspar. The internal arrangements of the minerals and the variation in rock texture in pegmatites was the subject of intense field study during the war period and since that time by the U. S. Geological Survey. The synthesis of the results of the field and laboratory investigations which amounted to approximately 68 man years is the work of the four authors, two of whom are Dartmouth men.
A. H. McNair, Professor of Geology at Dartmouth, was in charge of the studies in New Hampshire in 1944-1945. Lincoln R. Page '30 is at present the director of the pegmatite work of the Survey throughout the country and was in charge of the studies in the Idaho, Montana, Wyoming, South Dakota and Colorado region during part of 1942 and from 1943 to 1946. Earlier work in New Hampshire for the New Hampshire State Planning Commission by Professor H. M. Bannerman, member of the faculty at Dartmouth 1927-1946, introduced the technique of mapping the mineralogy of these masses in detail. From this grew the concepts of the zones characterized by specific minerals and textures which is the special contribution of this study. H. M. Bannerman was responsible for the guidance and direction of the program during the period 1942-1944 when he was in charge of the pegmatite investigations.
The field program included many Dartmouth men and others who at one time or another have served as instructors in the Department of Geology at Dartmouth. In addition to McNair, Page and Bannerman, 1927-1946, the list includes: D. M. Larrabee '32, J- J- Page '41' C- S- Maurice, Instructor '42, W. H. Ashley '45, R. P. Brundage '45, J. T. Callihan '42, J. H. Chivers '45, I. S. Fisher, Instructor '40, L. Goldthwait '36, J. B. Headley Jr. '42, H. Kamensky '46, H. R. Morris '45, F. H. Main '42.
Dartmouth was represented on the U. S. Geological Survey pegmatite study during the past summer by L. R. Page '30 in South Dakota, J. J. Page '41 and P. H. Brown '50 in New Hampshire, J. D. Vogel '50 in Colorado, and J. A. Redden '48 in North Carolina.
From the viewpoint of the geologist the monograph contains a wealth of information well illustrated by maps and is a fundamental milestone in our study of pegmatites. Considered with broader perspective one is impressed by the effectiveness of the combined efforts of these many men and proud that Dartmouth geologists are taking an important part in the endeavor to enrich our knowledge of this type of mineral deposit.
