318 Association of American Geologists and Naturalists. 
described from oral accounts over two hundred feet in height, and from 
two to fifteen miles in length; and some, which from careful admeas- 
urement, were found to be from two to thirteen miles in length. 
3. With regard to the nature of their movement, it was observed 
that it was very slow and perfectly steady, and in the direction of the 
great under currents which always tend from the poles to the equator, 
and that no rotary movement had ever been noticed; and indeed no 
remarkable movement except that produced by the overturn of the 
iceberg. Facts were mentioned illustrating the great depth of water 
in which icebergs sometimes ground, and that they thus remained 
grounded many years. ‘The limits of the transport of icebergs were 
shown from the facts observed to be about 40° of north latitude and 
36° south latitude. 
4. Many original facts were stated as to the transportation of bowl- 
ders, from a small size to the diameter of many feet, and from an ex- 
amination of the positive and negative testimony upon the subject, it 
was inferred that icebergs are rarely seen charged with foreign mate- 
rials except near their source. 
From the facts exhibited, the following inferences were drawn: 
1. The steadiness in the movement of the icebergs in our present 
seas, in the direction and under the influence of great under currents 
in our northern hemisphere from causes which must have prevailed as 
well in the ancient as in our present seas, favor the theory that icebergs 
with gravers of rock in their lower portions, or pressing the sand and 
gravel by their immense weight along the surfaces of the rocks in the 
bottom of the ancient oceans, might have scored and grated along the 
rocks, grinding off their salient points, and leaving their surfaces 
smoothed and striated in the fixed southerly direction in which they 
now occur. 
2. The immense magnitude of the icebergs in our present seas, and 
the evidence as to their present mechanical power, when moved by 
powerful currents, warrant the conclusion that they must have exerted 
a powerful influence in pushing and crowding along the sand and gravel 
which formed the bottoms of the ancient seas, and in thus forming ac- 
cumulations analogous to the moraines of the glaciers. 
3. The length of time during which icebergs may remain aground, 
even when swept by rapid currents which might surround them with 
sand and mud, or sweep away the loose materials, leaving hills or banks 
upon spots protected by the stranded icebergs, favors the idea that this 
agency had an influence in giving the present form to our drift. 
4. The formation of glaciers upon the present coasts under such cir- 
cumstances, that fragments of rock and detritus from the land upon 
which they form becomes attached to thern, the constant advance and 
