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August i, 1885.] The Australasian Scientific Magazine . 
belong to the same formation as the adjacent mountains, or to have been 
carried thither by tides or currents, etc. 
It is also desirable to obtain the fullest information respecting the 
changes which take place from time to time either in the line of 
coast or in shoals or sandbanks. The latter, particularly when 
occurring near the mouths of large rivers, or of such as bring 
down much detritus from the interior, like the Ganges or Mississippi, 
or even the Hermus in the Gulf of Smyrna, are liable to drift, according 
to the prevailing winds and currents at different periods. The line of 
coast is also often subject to considerable changes, in some places _ gradu- 
ally extending to the sea ; in others eating its way as gradually back inland ; 
and it is remarkable that it is precisely the bold and rocky cliff, which 
appears to offer such an insuperable barrier to the ocean waves, that 
crumbles away under their never ceasing attacks, particularly when unpro- 
tected by a sloping talus of shingle; while the low, flat, marshy coast, 
offering no visible resistance to the advancing waves, and constantly 
covered by the muddy waters, is that which, owing to the deposits of mud 
and silt left by each succeeding tide, is gradually raised above its former 
level until it forms a real barrier to the waves; while it is slowly extended by 
the same process far beyond the spot which the sea formerly reached. 
The nature of the shore should also carefully be ascertained ; whether it 
consists generally of sand or mud, or rocks, either in the shape of reefs, or 
occurring as detached blocks ; also whether the landing is easy or not 
on the beach ; and whether this consists of sand or shingle. What bays or 
coves occur along the line of coast to serve as harbours of refuge? What 
is the nature of the anchorage ? Are there any harbours along the coast ? 
And how far have natural harbours been rendered more available and safe by 
the erection of breakwaters or piers ? 
7. Oceans , their Depths and Currents ; Islands, Rocks , Shoals , etc . — 
Having completed the enumeration of the principal features to be noticed 
on shore, I must now point out some of those which call for the notice 
of the geographer at sea. With regard to the ocean itself, many of the 
objects of inquiry are the same as those I have already mentioned with 
respect to lakes. Its depth and its colour, as well as other peculiarities, 
must be noted. The nature of the bottom should more especially be 
ascertained, whether consisting of mud or sand, or rock ; when varied, the 
extent of each should be noticed. Not only is the important question of 
a good holding ground, or anchorage, connected with these facts, but the 
natural productions to be found in the different seas depend chiefly on 
the character of the bottoms, and the algae and other marine plants which 
grow on them. The direction and strength of the currents must also be 
observed, as well ns their prevalence or usual duration where liable to 
change. Prevailing winds should also be noticed. Tides also must 
not be forgotten ; their amounts as well as their periods and durations 
are important. In some inland seas they appear to be influenced 
by meteorological than astronomical causes, to be dependent on the 
force of regular winds rather than on the attraction of heavenly bodies. 
But other incidental pecularities also require notice, such as storms 
and tempests, hurricanes and tornadoes, particularly when of frequent 
occurrence, or when recurring at regular intervals or at certain 
periods of the year. The permanent effects produced by them (if 
any) should also be registered, such as surfs, breakers, rollers, etc. In 
the next place the geographer must direct his attention to the islands, 
rocks, or shoals, which occur in different seas ; their extent and position 
