624 
APPENDIX. 
[C. 
extensive surface ; — a collection ought therefore to furnish 
specimens of the most characteristic varieties ; — and the 
most splendid specimens are, in general, not the most in~ 
structive. Where several specimens are taken in the same 
place, a series of numbers should be added to the note of 
their locality. 
5. One of the most advantageous situations for obtaining 
specimens, and examining the relations of rocks, is in the 
sections afforded by cliffs on the seashore ; especially 
after recent falls of large masses. It commonly happens 
that the beds thus exposed are more or less inclined ; and 
in this case, if any of them be inaccessible at a particular 
point, the decline of the strata will frequently enable the 
collector to supply himself with the specimens he wishes 
for, within a short distance. Thus, in the subjoined sketch, 
which may be supposed to represent a cliff of considerable 
height, — the observer being situated at a, the beds b, c, d, 
though inaccessible at that place, may be examined with 
ease and security, where they successively come down to 
the shore, at b', c\ and d'. 
6. To examine the interior of an unknown country, more 
skill and practice are required : the rocks being generally 
concealed by the soil, accumulations of sand, gravel, &c., 
and by the vegetation of the surface. But the strata are 
commonly disclosed in the sides of ravines, — in the beds of 
rivers and mountain-streams ; and these, especially where 
