212 Maclure on Geology. 



What Werner calls primitive trap may perhaps be compact 

 hornblende, or perhaps the newest flaetz trap, when it hap- 

 pens to cover the primitive ; for, this species of trap, like the 

 currents of lava, covers indiscriminately all classes of rocks, 

 and is one reason why I consider it as the remains of ancient 

 lava. 



Transition trap is a rock that I have not met with, and may 

 perhaps be a part of the flaetz trap that happened to cover the 

 transition, without any immediate connexion, but like a cur- 

 rent of lava, overlying all the classes of rocks it meets with. 

 This misapplication of names naturally arises from the sys- 

 tem of neptunian origin, on which the nomenclature of Wei'ner 

 is founded. ' 



Greywake and greywake slate are aggregates of rounded 

 particles of rocks, evidently the detritus of more ancient 

 formations, and differ from the aggregates of pudding and sand- 

 stone of the secondary class, in the following properties, viz. 



. The aggregates of transition are harder and much more com- 

 pact, than the secondary ; they are also cemented by argil, 

 taking a slaty form. 



This cement is in much greater quantity, in proportion to 

 the particles cemented, and has the appearance as if the 

 cement at the time of formation, had a consistence sufiicient to 

 prevent the particles from touching each other. 



They have, in common with all the transition rocks, a regu- 

 lar and uniform dip from the horizon, from 10 to 40 degrees; 

 and sometimes more. This is perhaps the strongest mark of 

 distinction which separates them from the secondary, which 

 are horizontal, or follow the inequalities of the surface oa 

 which they were deposited. 



The transition are distinguished from the primitive in being 

 aggregates of rounded particles, having little or no crystalliza- 

 tion, and containing, or alternating with strata, which contain 

 organic matter. 



The oldest red sandstone, with all its accompanying strata, 

 I should incline to put into the transition, as having many of 

 the properties of that class, and occupying the same relative 

 situation in -the stratification of the globe. It is at a constant 



