228 
Instructions to the 
from land, the latitude and longitude at which they are ob¬ 
served ; their state of preservation ; the position of the trees, 
if upright; if with their foliage or fruit. 
Islands. —Examine all islets and detached rocks, and ascer¬ 
tain if they consist solely of one description of rock, or of beds 
of different composition. Take numerous specimens from the 
antarctic islands, with notes of position, &c. 
Examine how far islands of the same group correspond in 
form, and in the direction of their hills and valleys. 
When numerous islands are composed of the same material, 
examine whether there is any difference observable in the nature 
of the detritus, or gravel upon their surfaces. 
Inquire what effect wind has in the formation or enlargement 
of land in southern latitudes. 
Elevation of land. —Observe appearances which indicate the 
elevation of land, as the high inclination, curvature, fracture, 
and open fissure of strata: sketches should be made where 
these are remarkable. 
Endeavour to ascertain whether the lines or ridges produced 
by such elevations are continued to any great extent; and, if 
more than one such ridge he found, whether they are parallel. 
In all islands, seek for traces of gravel and sea-beach, at 
points above the present level of the sea. Measure, or estimate, 
the level of such places. 
Terraces. —Record all indications of terraces, in valleys or 
along sea-coasts ; the extent to which they may be traced; 
whether horizontal or inclined,—interrupted, or traceable at 
intervals. If more than one line of terrace occurs in the same 
valley or cliff, determine or estimate their elevation above the 
sea, and the vertical distance between each terrace; examine 
the materials of which they consist, whether of shingle, sand, 
or clay; whether they contain any remains of Testacea , and if 
so, whether the shells are marine or of fresh-water. 
The elevation on the coast of Chili after the earthquake of 
1802 , has been questioned by MM. d’Orbigny and Gay; 
(Comptes Itcndusy 1837, page 154). Seek for evidenoe on tlii; 
question. 
Depressions of the land. —Notice carefully all indications 
of subsidence of land;—as of the tide reaching deserted houses, 
or other human works partially or wholly exposed at low water. 
Whether beds of peat, or stumps of trees, are exposed during 
any state of the tide, or can be seen constantly covered with 
w r ater. In making these observations, attend particularly to 
the outline of the coast$ and state wdiether these indications 
occur in estuaries, bays, or along straight, open shores, free 
from sand-banks. 
Structure and forms of land. —Make drawings, as often as 
possible, of the land seen, whether visited or not. Where the 
