Geology.] 
NATURAL HISTORY. 
625 
they cross the direction of the strata, and be made, by 
careful examination, to afford instructive sections. 
7. Among" the distinctive circumstances of the strata, 
the remains of organized bodies, — shells, corals, and other 
zoophytes, — the bones and teeth of animals, — fossile wood, 
and the impressions of vegetable stems, roots, or leaves, <^c., 
are of the greatest importance ; affording generally the most 
marked characters of the strata in which they occur. — ^These 
should, therefore, be particularly sought after, and their 
relative abundance or rarity in different situations noticed. 
The petrified bodies should, if possible, be kept united with 
portions of the rock or matrix in which they are found ; and 
where they are numerous, — in sand, clay, or any moist or 
friable matrix, — it is in general better to retain a large por- 
tion of the whole mass, to be examined afterwards, than to 
attempt their separation at the time of collecting. 
8. The loose materials which are found above the solid 
rocks, in the form of gravel, silt, rolled pebbles, <^c., should 
be carefully distinguished from the solid strata upon which 
they repose. And the more ancient of these loose materials, 
found on the sides or summits of hills, ^c., should be distin- 
guished from the recent mud, sand, and gravel, brought 
down by land- floods, or rivers. The bones and teeth of 
animats are not unfrequently found in gravel of the former 
description ; and the collection of these remains from distant 
quarters of the globe, is an object of the greatest interest 
to geology. 
9. Besides a note of the locality, there ought, if possible, 
to accompany every specimen, a short notice of its geological 
circumstances; as — 
Whether it be found in large shapeless masses, or in 
strata ? 
VoL. IL 2 S 
