DILUVIUM. DRIFT AND ERRATIC BLOCKS. 



7C1 



marsh was hard frozen. The Needle mountain in Dauphiny, described as erratic, is a 

 thousand paces in circumference at the top, and two thousand at the base. Near Neuf- 

 chatel a mass of granite occurs, forty feet high, fifty long, and twenty broad, estimated to 

 weigh 3,800,000 pounds. On the Jura limestone mountains, at an elevation of 2000 feet 

 above the Lake of Geneva, there are granitic blocks, the solid contents of which amount 

 to 1200 cubic feet upon the Sal ere, to 2250 on the Coteau de Boissy ; and the block 

 called Pierre a Martiji is mentioned by Mr. Greenough as containing even 10,296 cubic 

 feet. The rock in Horeb, from which, according to monkish tradition, the leader of 

 Israel miraculously drew water, is a mass of sienitic granite, six yards square, containing 

 5823 cubic feet, lying insulated upon a plain near Mount Sinai. Professor Hitchcock 

 remarks of the United States : "In this country boulders occur of equal dimensions. 

 Thus, on Cape Ann and its vicinity, I have not unfrequently met with blocks of sienite 

 not less than thirty feet in diameter ; and, in the south-east of Bradford county, I noticed 

 one thirty feet square, which contains 27,000 cubic feet, and weighs not less than 2310 

 tons. In the west part of Sandwich, on Cape Cod, I have seen many boulders of granitic 



^^ gneiss, twenty feet in diameter, 



which contain 8000 cubic feet, and 

 weigh as much as 680 tons. Two 

 greywacke boulders of the same 

 size lie a few rods distant from the 

 meeting-house in Norton, in Dr. 

 Bates's garden. A granite boulder 

 of equal dimensions lies about half 

 a mile south-east of the meeting 

 house in Warwick ; and one of 

 similar dimensions lies on the west 

 ern slope of Hosac mountain, at 

 least 1000 feet above the valley 

 Drift near Cape Cod. over which it must have been trans 



ported. One of granite lies at the foot of the cliffs at Gay Head, on Martha's Vineyard, 

 which is ninety feet in circumference, and weighs 1447 tons. At Fall river there 

 is a boulder of conglomerate which originally weighed 5400 tons." But the in 

 stances are endless that might be 

 given of similar large and insulated 

 masses, now lying at a remote 

 distance from the parent rocks 

 from which they have been ab 

 stracted. Wandering in the south- 

 em extremity of America, Mr. 

 Darwin speaks of his course being 

 obstructed by well-rounded pebbles 

 of porphyry, mingled with immense 

 angular fragments of basalt and of 

 primary rocks, nearly seventy miles 



Rocking Stone, Fall river. 



apart from the nearest analogous 

 mountain ; while in Europe the vast 

 plains of Prussia, Poland, and Russia, 

 comprehending a zone of country near. 2000 miles long and from 400 to 800 miles wide, 

 are strewed with loose detritus and crystalline blocks of colossal size, all of which have 

 been transported from the mountain masses of Scandinavia. 



