438 WARREN AND POWERS DIAMOND HILL-CUMBERLAND DISTRICT 



lished by Emerson and Perry,- where the two maps overlap, will show 

 certain points of difference. However, the very considerable care with 

 whicli the writers have gone over the area in question inspires them with 

 considerable conlidence as to the accuracy of the map herewith presented. 



Previous Work 



The first work on the general region of wliich the present limited area 

 is a part was done by Dr. C. T. Jackson and was recorded in his report 

 on the "Geology and Agriculture of the State of Ehode Island," pub- 

 lished in 1840. The next work of importance was by Shaler, Wood- 

 worth, and Foerste in their monograph^ on the '^Geology of the Narra- 

 gansett Basin."' Professor Woodworth in his section of the monograph 

 describes some of the igneous and sedimentary rocks occurring in the 

 region now under consideration. B. K. Emerson and J. H. Perry, in the 

 bulletin previously referred to, discuss the green schists and associated 

 rocks in the region south of Iron Mine Hill. B. L. Johnson* has de- 

 scribed briefly the geology of Iron Mine Hill, and one of the authors has 

 described in considerable detail the petrography of the cumberlandite 

 and the closely associated gabbro^ from the same locality. 



Location and Topography 



The Diamond Hill-Cumberland Hill area is located at the northeast- 

 ern corner of the State of Ehode Island and in the adjoining part of 

 Massachusetts. The westei-n odoe of the district is a mile east of Woon- 

 socket, Ehode Island. 



In the center of the area is Copper 31ine Hill, on the east is Diamond 

 Hill, and on the west is Iron Mine Hil]. All three hills rise to an eleva- 

 tion of over 400 feet above sealevel, or about 300 feet above the two 

 streams in the region — the Blackstone Eiver on the west and Abbotts 

 Eun on the east. On the north the upland topography continues beyond 

 the boundary of the map. 



The relation of topography to bedrock geology is clearly shown. The 

 three hills mentioned above consist of igneous rock, as does the ridge to 

 tlie north. On the northwest and southeast are rather flat, low regions 

 underlain by the softest and most easily eroded rock in the region — Car- 

 boniferous sediments. The meandering brooks in these low regions are 



2 Bull. U. S. Geol. Survey No. 311. 



3 Monograph U. S. Geol. Survey No. 33. 

 * Am. Jour. Scl., vol. 23, 1908, pp. 1-12. 

 ^ Am. .Tour Scl.. vol 25. 1908. pp. 12-.'5S 



