84 GRAYWACKE. SANDSTONE. 



particles become very minute, it passes into com- 

 mon clay-slate; and when the particles are very 

 numerous, and united by a small quantity of cement- 

 ary matter, it becomes a sandstone or gritstone; 

 and when the fragments are still larger and angular, 

 it is called a hreccia; when rounded, pudding-stone. 



What is called old red sandstone by geologists is 

 only a species of graywaeke coloured red by oxide 

 of iron. They may often be observed passing into 

 each other, and alternating with mountain lime- 

 stone ; it also passes into claystone by losing its 

 granular structure. The old red sandstone is so 

 called because it is believed to lie lower down, or 

 nearer the primitive rocks than another species, 

 called the new red sandstone ; but, on the Continent 

 of Europe, the old red and coal formations have 

 been classed as the upper members of the transi- 

 tion series, a method adopted by Dr. Buckland in 

 his late Bridgewater Treatise. 



Red sandstone is a rock of considerable impor- 

 tance as a building material. When beds of clay 

 alternate with this rock, the soil is generally very 

 fertile ; but where the sandstone alone prevails, the 

 land is mostly barren. A deposite of sandstone 

 extends, with few interruptions, from Vermont, 

 through Massachusetts and Connecticut, down Con- 

 necticut River to Middletown, thence to New-Ha- 

 ven, thence to Virginia, a distance of seven hun- 

 dred miles.* 



Sandstone contains impressions of plants and 

 fish, charred wood, and numerous minerals, such 

 as copper and lead, at Simsbury, Conn. ; Belleville, 

 Somerville, &c., N. Jersey ; and Perkiomen, Penn., 

 &c. In some parts of England the old red sand- 

 stone formation is computed to be at least 10.000 

 feet thick. 



* Lieut. Mather. 



