514 abstracts: geology 



which is close- to the percentage of potash in glauconite, of which the 

 best greensands are almost entirely made up. These greensands 

 occur in the basal part of the Cretaceous formation of New Jersey and 

 Delaware and in the upper part of the Eocene. Those of New Jersey 

 are entirely in the Cretaceous, while those of Maryland are in both 

 Cretaceous and Eocene. 



The paper also contains a contribution on Methods of analysis of 

 greensands by William B. Hicks and Reginald K. Bailey, discuss- 

 ing the methods used in making these analyses, which differ some- 

 what from methods previously used. G. H. A. 



GEOLOGY. — The Irvine oil field, Estill County, Kentucky. Eugene 

 W. Shaw. U. S. Geol. Survey Bull. 661-D. Pp. 141-191. 1917. 



The report outlines the history of the Irvine oil field, which in three 

 years has developed into the richest oil territory in the state, and de- 

 scribes the geology, including the nature and lay of the rocks, the char- 

 acter and occurrence of the oil, and other features of the field. The re- 

 port contains one map, 20 by 30 inches, showing the structural geology, 

 farm lines, wells, and other features on a scale of 2 miles to the inch, and 

 another map showing the general geologic structure of about 1000 

 square miles surrounding the field on a scale of 4 miles to the inch. 



The Irvine oil field is by far the most productive yet developed in 

 Kentucky. In fact, its output in 1917 will be more than twice as 

 great as that of the dozens of other oil fields in the State, some of 

 them long productive; and it will probably produce much more in 

 1918. The field is in a region where oil showings have long been 

 known and oil has long been sought, and yet somehow this great pool 

 10 miles long and 2 miles wide was missed. The west side of the Irvine 

 field is within a mile of outcrops of the oil-bearing bed, which may be 

 seen at several places in and around Irvine. Some of the wells are 

 less than 100 feet deep and yet furnish good yields, even the oldest 

 showing a relatively low rate of decline. E. W. S. 



GEOLOGY. — Geology and ore deposits of the Mackay region, Idaho. 

 Joseph B. Umpleby. U. S. Geol. Survey Prof. Paper 95. Pp. 

 129. 1917. 



The Mackay region is in southeastern Idaho north of Snake River. 

 It has yielded about $3,750,000, of which $2,300,000 has come from 

 copper, and the remainder from silver, lead, and gold. 



