TITLES AND ABSTRACTS OF PAPERS 155 



SOME PROBLEMS OF THE ADIRONDACK PRECAMRIAN 

 BY HAROLD L, ALONG ^ 



i Abstract) 



During the detailed investigation of the Adirondacl?: graphite deposits evi- 

 dence was gathered that points to the following conclusions : That the Gren- 

 ville series is extensivelj' folded and severely metamorphosed ; that the graph- 

 ite schists furnish a basis on which a thousand feet of the series can be studied 

 stratigraphically ; that there is the probability of metagabbro masses that 

 antedate the Laurentian granite. The Laurentian granite is present through- 

 out the eastern and southeastern Adirondacks. There is evidence that there 

 is another metagabbro that is later than the Laurentian granite, but older than 

 the anorthosite-syenite-granite-gabbro series. Laccolithic bodies of the gabbro 

 and diabase were seen. On the shore of Lake Champlain dikes of diabase, 

 camptonite, and bostonite have such field relations that their relative ages can 

 be determined. 



PERMO-TRIASSIC OF NORTHWESTERN ARIZONA 

 BY HERVEY W, SHIMER 



(Abstract) 



Two months of field-work in Arizona, extending from Flagstaff, northwest^ 

 ward through the Painted Desert, over the Kaibab Plateau, and into the Tor- 

 roweap Valley, resulted in many fossil collections from some fourteen, some- 

 what less accessible, localities. The collections here considered were made 

 from the Kaibab limestone (Permian) and the Moencopie shales (Triassic). 



STRATIGRAPHY AND STRUCTURE OF THE NEWARK SYSTEM IN MARYLAND 



AND ITS RELATION TO THE NEWARK SYSTEM OF 



EASTERN NORTH AMERICA 



BY GEORGE EDWIN DORSEY ^ 



(A'bstract) 



Studies made of the Newark System in Maryland and the immediately ad- 

 jacent areas of Pennsylvania and Virginia during the spring, fall, and winter 

 of 1917 and the spring of 1918 have led to new conclusions regarding the 

 stratigraphy and structure of this problematical series of red beds. The 

 Maryland areas of Newark rocks are critical, in that they afford very con- 

 vincing evidence on fundamental and far-reaching conclusions as to the struc- 

 ture of the red rocks. 



Three separate areas of Newark rocks are found in Maryland ; a northern 

 area, covering parts of Frederick and Carroll counties, the largest of the three, 

 areas : a central region^ — the smallest — extending as a narrow strip south from 

 Frederick to the Potomac River, and a third southeastern area, lying almost 

 wholly in southwestern Montgomery County. 



^ Introduced by H. L. Fairchild. 

 2 Introduced by E. AY. Berry. 



