the Formation of Rocks. 187 



It will be objected to this opinion, almost universally, that 

 tsand, sandstone, and clay, are nothing else but debris result- 

 ing from the weathering and mechanical destruction of the 

 older rocks, which has been washed together by water. I am 

 myself of the opinion, that much owes its origin to such pro- 

 cesses ; but I am also convinced, that a large, and indeed by 

 much the largest, portion of the rocks that are regarded as of 

 secondary* origin, have been formed in a similar way to the 

 older formations, and are only a continuation of them. 



Let us only consider what masses must have been destroyed, 

 and what must have been necessary for converting these masses 

 into fine quartzose sand, and mud-like clay ; let us consider, 

 if the clay, which is included so universally, and in such large 

 quantity, in the newer calcareous formations, could have form- 

 ed a part of these, if it had been washed thither, and had not 

 been formed simultaneously with the limestone. This clay 

 not unfrequently passes into a substance resembling hornstone, 

 in which certainly we can see no more appearance of a mecha- 

 nical origin, than in the flint of the chalk formation, which be- 

 longs to the last members of the siliceous series, and only dif- 

 fers from quartz-rock, in the imperfection of its development. 

 The sharp edges andj angles of the grains of many sandstones 

 are also adverse to a secondary origin ; and even if they were 

 rounded, this would be by no means a conclusive proof of such 

 an origin, inasmuch as they might have acquired this charac- 

 ter during their formation in agitated water, where crystalliza- 

 tion was disturbed, just in the same manner as hailstones. 

 Portions of quartz, having quite the aspect of rolled pebbles^ 

 sometimes occur in veins. In many sandstones no uniting 

 basis can be recognised, and the grains are sometimes so inti- 

 mately blended, that the whole mass cannot be distinguished 

 from some kinds of primary quartz; and the natural conclu- 

 sion is, that it must have been formed in the same manner as 

 the latter. 



2. The Calcareous Series. — This series commences with the 

 siliceous series, in the primitive class of rocks, and constantly 



* The term secondary, is here, and in another sentence, used, not to de- 

 signate a class of rocks, but in opposition to the term original, as exiMve- 

 sive of the formation of particular rocks. — Edit. 



