Maclure on Geology. 213 



dip (although small) from the horizon ; the cement is in 

 greater quantities in proportion to the particles cemented than 

 in any of the secondary aggregates, &;c. he. 



The character of the secondary is a horizontal position, that 

 perhaps does not admit of the same facility of examining the 

 relative situation of its stratification. The compact limestone 

 is, probably, with reason, considered as the lowest of the se- 

 condary formation, and always under the coal formation, but 

 it appears to me that the secondary is deposited in basins 

 alongside of one another, and that each basin has a different 

 order of superposition, according to the nature of the agents 

 employed in the deposition ; that it is a partial, and by no 

 means a general deposition. The secondary aggregates of 

 sandstone and puddings have been evidently beds of sand or 

 gravel, and of course, in that state would be called alluvial, 

 but when cemented together by the infiltration of water, car- 

 rying along with it lime, iron, or any other body capable of 

 agglutinating the particles together, become rocks, and may 

 alternate in all proportions. 



I am therefore inclined to think, that in geology the best 

 inode for the greatest part of the secondary would be to give 

 the relative position of the strata of each valley or basin ; 

 and I am rather of opinion that they would all differ from one 

 another. 



The French and English basin having chalk for the lowest 

 stratum, which has occupied the geologists of both couatries 

 for these 10 or 15 years, is perhaps the best known ; yet they 

 do not know the relative position of the chalk and coals, be- 

 cause coals have not been found in the same basin with chalk : 

 eoals occupy basins filled with different kinds of rocks, and 

 have no resemblance to the rocks found covering the chalk 



