280 



DILUVIUM. 



periods, is far better supported by existing facts, 

 and is probably that which will eventually be adopt- 

 ed by most geologists. Professor Hitchcock, who 

 is a close and accurate observer, as well as philo- 

 sophical reasoner, concludes, after the most thor- 

 ough examination, that " all the diluvium, which 

 had previously accumulated by various agencies, 

 has been modified by a powerful deluge, sweeping 

 from the north and northwest over every part of 

 Massachusetts, not excepting its highest mountains; 

 and that, since that period, none but alluvial agencies 

 have been operating to change the surface." 



Every part of the United States, and we may say 

 the same of northern and middle Europe, if not 

 Asia, exhibits abundant evidence of a similar flood 

 from the north ; as shown by rocks and bowlders 

 being generally found south of the ledges and strata 

 from whence they were originally dislodged. 



These bowlders are in some parts of the country 

 strewn over the surface in immense quantities, and 

 always correspond with the rocks lying north of 

 them. They are found on the sides and tops of 

 mountains, of a different species of rock from that 

 which forms the mountain itself; and we know of 

 no other cause but a powerful flood to explain the 

 phenomenon. They are often of great size, fre- 

 quently 20, 30, or even 40 feet in diameter, and oc- 

 casionally they are so delicately poised upon an- 

 other rock as to be easily moved. They are then 

 called rocking-stones ; and some, weighing over 100 

 tons, can be easily moved by the strength of a single 

 man. No one can travel over New-England with- 

 out being impressed with a full conviction that, at 

 some former period, an immensely powerful current 

 of water has swept over the land. 



But it is not to be inferred that the diluvial forma- 

 tion is always level, or nearly so ; on the contrary, 

 it is often piled up into elevations whose surfaces 

 exhibit curves of every description, while the cor 



