200 
Hints for the Formation of 
parallelism* The parallelism of these divisions with the 
laminae or parts discernible in the inside of the mass* 
4. Though the strata, in general, have the form of a 
parallelopipedon, some are seen cuneiform ; in others are 
observed alternate swellings and constrictions ; and 
others are seen ramiiied, dividing themselves sometimes 
into two or three, or two and three uniting and forming 
themselves into one. 
5. Besides the form of the strata, to observe their ex- 
tent, either in the same mountain, or in several mountains 
near each other, or even at a distance. 
6. To observe also 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 last observation determines the direction of their 
planes, or the two opposite points of the horizon through 
which their planes would pass, were they prolonged, af- 
ter being made entirely straight. This direction of the 
planes is of importance to be considered, especially in 
vertical strata. 
7. To examine whether this direction is parallel, ob- 
lique, or transverse to the direction of the body itself of 
the mountain, the chain of which it makes a part, and the 
adjacent valleys. 
8. To examine also whether the declivity of the strata 
is conformable to that of the external surface of the 
mountain ; that is to say, whether they descend towards 
the outside of the mountain, or towards the interior part. 
9. To examine next whether the inclination is the 
same from the bottom of the mountain to the summit, or 
whether it varies at different heights ; whether it be the 
same or different at the opposite sides of the same moun 
tain. Strata in the form of a fan.* 
Voyages dans les Alpes. § 656 and 67 ? , 
