182 aEOLOGY OF THE IsTARRAGANSETT BASII^. 



Dr. A. F. Foerste also fonnd in the sandstones of this area calamite trunks 

 6 inches in diameter. 



Coal — A "bed of coal said to be 6 feet thick was met with in digging a 

 well on the land of Mr. Charles P. Simpson in the autumn of 1890. This 

 locality is in the southern part of Wrentham, near the Attleboro boundary 

 Hne and on the eastern face of Blake Hill block. (See PL XI.) The well 

 is reported to have passed through the following strata: 



». 

 Bection of well mar Attlehoro, Massaeliusetts. 



Feet 



Sandstone 24 



Goal, anthracite 6 



^' Flinty sand rock,'^ thickness unknown. 



Westwardljj gray conglomerates overlie the coal section, and east- 

 wardly sandstones crop out from beneath it. It is shown by these latter 

 beds that the dip is here gentle to the southwest. The outcrop of the coal 

 bed is about 260 feet above sea level and from 20 to 25 feet above the level 

 of the pond in the northwest part of North Attleboro. Southward of this 

 locality the Bkke Hill block is probably cut oif by a fault, as basal arkoses 

 come in at the distance of half a mile along the strike line. Northwestward 

 along the strike the conditions appear favorable for exploiting this bed along 

 the western side of the Plainville Valley. 



Yet farther eastward, and lower down, micaceous sandstones crop out 

 along the roadside and contain impressions of trees of small size. At other 

 points along the southern edge of the Blake Hill block the waste from 

 highly carbonaceous shales occurs in the glacial drift. 



This block of strata dips throughout to the westward, the dip increasing 

 from near hoiizontality along the eastern boundary at Plainville to 30° and 

 45° along the western, ill-deiined margin. The western contact is appar- 

 ently made with, the red Wamsutta series. It appears as if this block, 

 over a mile in width and about 3 miles in length, had been thrust into its 

 relatively nndisturbed position, while the strata around it on the east, south, 

 and west, as well as the beds beneath its eastern foot, had been thrown into 

 steep folds and even overturned. It will be noted that the Blake Hill block 

 lies north of and behind the Hoppin Hill granitite boss, around which the 

 horseshoe fold of the Wamsutta is bent 



The stratigraphic position of the block can be only vaguely stated. 



