230 
Instructions to the 
This is an important character, and great care should be 
taken to distinguish it from stratification. A paper by Pro¬ 
fessor SedgwicK in Geol. Trans. 2d Series, Vol. III. ought to 
be consulted upon this subject; and endeavours should be made 
to determine whether the uniformity there pointed out, in the 
magnetic bearing of the cleavage planes, exists in the southern 
regions. 
Floating masses of ice .—Note their position with respect to 
latitude and longitude, and the stony or earthy materials which 
may be found upon or within them. 
On the shores of islands, or on coasts much exposed to the 
action of floating icebergs, observe what effect is produced on 
the surface of the rocks by their friction. 
Inquire if there be reason to believe that icebergs, when 
aground, stir up and disturb the sediment, or otherwise affect 
the bottom. 
2. Erratic Blocks. 
This name has been given to masses of rock often found loose 
upon the surface, which commonly differ from the stone of the 
country, and are sometimes very distant from rock masses like 
themselves. Seek for these, especially in islands, or at places 
above the present level of the sea. Take specimens of them ; 
note their form, whether irregular, rugged, smooth, or polished ; 
their composition, whether like any known masses seen else¬ 
where; if different from that of the rocks in the adjacent 
country ; whether the rocks on which they rest arc furrowed; 
if most numerous on the summits of ridges, or in valleys; if 
arranged in any order; if more numerous in one part of a ridge 
or valley than in others. 
Great erratic blocks are said to occur on the shores of the 
New Shetland Islands, consisting of granite, which is not found 
to compose the adjacent rocks.—See Cordier’s Instructions. 
(Comptes Rendu* , 1837, pages 152—154). 
See the Account of an American Expedition of Discovery to 
the South Polar Regions in 1830. 
For an account of the blocks in the glaciers of Spitzbergen , 
see De Beaumont's Instructions. ( Comptes Rendus , 1838, 
p. 22.) 
3. Volcanic Phenomena. 
Record all indications of recent volcanic character; jets of 
smoke; of flame by night. 
Connect the places where these are observed with the nearest 
observations of latitude and longitude. 
In volcanic countries, or those liable to earthquakes, record 
all the remarks of the natives, and note particularly whether 
the people are silent with respect to changes of level. 
