SHODILTES, HOLS SURGE NIES: 7 
through any such distances as the drift has been carried. On 
the contrary, we have the best of reasons for believing that they 
could not. 
| WIND. = 
The strongest winds are able to carry no more than very 
small pebbles along with the sand and dust which make up their 
chief load. Transportation of the drift by the wind is therefore 
impossible. Locally the wind has moved the sand of the drift, 
heaping it into dunes or spreading it with more uniformity over 
surfaces which it did originally occupy. But although the wind 
may have played a part in the deposition of the great body of 
material included under the term drift, either at the time of its 
origin or since, it can have been no more than a very subordinate 
factor. The work of the wind, so far as the great body of drift 
is concerned, can be looked upon as nothing more than incidental. 
There remain to be seriously considered, therefore, only two 
agencies, ice and water. 
WATER. 
Next to the wind, moving water is by far the most widely 
active agent which is now shifting material on the earth’s sur- 
face. The countless streams, large and small, the waves and 
currents of the thousands of lakes, as well as those of the seas, 
are constantly moving those materials which come within their 
reach, and do not exceed their power. Streams, waves and cur- 
rents, do each their appropriate work. The results have much 
in common, yet each has its diagnostic marks. 
Streams. Streams sometimes carry heavy burdens of earthy 
material. If the velocity of a stream be great, and particularly 
if its gradient be high, it is able to roll along stones of consid- 
erable size. The torrents which course down hillsides after vio- 
lent showers sometimes carry blocks of stone weighing hundreds 
of pounds. If the high velocity of the transporting stream 
were to be constantly maintained, great quantities of coarse 
material might thus be carried down in the long process of time. 
The presence of coarse material, even bowlders of some size, is 
