82 LITE WOULINALENOLNGIE OF OGN- 
source. If its border were anywhere marked by heavy accumu- 
lations, it should be where special topographic relations limited 
the movement of abundant bergs. 
The border of the drift is often ill-defined, but it does not 
feather out to any such extent as this hypothesis would demand. 
The border is also frequently well defined, being marked by 
heavy beds of drift, and this where there is nothing in the topog- 
raphy or topographic relations to occasion local accumulation 
by means of icebergs. 
When specific features of the drift, or other specific phe- 
nomena accompanying it, are examined, they are found to afford 
significant testimony touching the iceberg hypothesis of the 
drift. If it be inquired whether icebergs could striate the surface 
on which their drift lies, it may be answered that this could be 
done to a very limited extent only. An iceberg could not. 
striate bedrock, so long as it was floating. When and where it 
grounded, it might produce markings upon its bed, but these 
could hardly be continuous for great distances. Neither would 
they be straight as a general rule. Bergsare likely to swerve as 
they ground, and any striae they might produce would cor- 
respond with the direction of this swerving motion. Strie 
believed to have been made by icebergs have been seen in a few 
localities, possessing the characteristics which might have been 
anticipated. 
To be brought into existence by icebergs, the divergent 
systems of striae observed beneath the drift would demand an 
impossible system of atmospheric or aqueous currents. Refer- 
ence need only be made to the figure (Vol. II., p. 849) showing 
the arrangement of striz in eastern Wisconsin. No system of 
air or water currents could drive the icebergs in such directions 
as to produce this remarkable system of stria#. Much less could 
there be systems of air or water currents which would occasion 
the repetition of the general features of this system many times 
within the area of drift. Icebergs would also be altogether 
incompetent to account for the production of striz in many of 
the anomalous positions in which they occur, such as the under- 
