a Theory of the Earth. 153 



ftratified, or compofed of ftrata, is the fuppofition that unrati- 

 fied mountains have been formed bv the fucceflive depofition 

 of fubftances before fufpended in a fluid, while thole which. 

 exhibit no figns of ftrata maybe fuppofed to owe their origin 

 to a fimultaneous creation, or an accumulation not formed 

 in a fluid, or which, at leaft, had nothing fucceflive or re- 

 gular, or in which there remain no traces of regularity. 



3. If the mountain or mafs exhibits no marks of divifion, 

 the queftion of its being Gratified or not is fupeifluous. We 

 mail fuppofe then that it prefents divifions, and require to 

 know whether thcfe divifions may be calledy/rato. The fo- 

 lution of this queftion depends upon three considerations: 

 viz. The regularity of thefe divifions, or their parallelifrn. 

 Their number : the greater the number, the more it excludes 

 the idea of fortuitous parallelifrn. The parallelifrn of thefc 

 divifions with the laminae or parts difcernible in the infide 

 of the mafs. 



4. Though the firata, in general, have the form of a 

 parallelopipedon, fome are feen cuneiform ; in others are 

 obferved alternate fwellings and conftriclions ; and others 

 are feen ramified, dividing themfelves fometimes into two or 

 three, or two and three uniting and forming themfelves into 

 one. 



5. Befides the form of the ftrata, to obferve their extent,* 

 either in the fame mountain, or in feveral mountains near 

 each other, or even at a diltance. 



6. To obferve alio their inclination, or the angle which 

 they form with a horizontal line, and the point of the ho- 

 rizon to which their declivity is directed. 



This laft obfervation determines the direclion of their 

 planes, or the two oppofite points of the horizon through 

 which their planes would pals, were they prolonged, after be- 

 ing made entirely ftraight. This direction of the planes is 

 of importance to be confidered, efpecially in vertical firata. 



7. To examine whether this direclion is parallel, oblique 

 or traufverfe to the direclion of the body itfelf of the moun- 

 tain, 



