454 
SCOUTING FOR GIRLS 
boulders, where they are found, evidence of the place 
where the glacier melted off (terminal moraine). Do 
these boulders increase or decrease in size as we go south 
over the glaciated area? Can you discover any place 
where they can be traced back to their native ledge? 
Present-day glaciers, like the Muir Glacier in Alaska, 
can be seen transporting boulders and drift just as this 
great prehistoric ice-sheet must have done. 
The drift which consists of clay mixed with pebbles, 
cobblestones, and boulders, varies greatly in depth. In 
some places there is none, while at St. Paris, Ohio, it is 
550 feet deep. It probably averages 100 feet thick or less. 
Un your locality note the depth of the drift in cuts made 
naturally by creeks and rivers or those made artificially 
for railroads. Oil-wells furnish evidence on this point. 
Collect a few good examples of scratched or glaciated 
pebbles or cobblestones which are abundant in the drift. 
These were scratched while frozen in the bottom of the 
glacier and pushed along on the bed-rock under the weight 
of the ice above. 
Collect ten different kinds of rocks from the glacial 
boulders and drift, — there are more than pne hundred 
kinds to be found, — and with the aid of some such book 
as “Rocks and Rock Minerals,” by Louis V. Pirsson 
(John Wiley & Sons) or “Common Minerals and Rocks,” 
by Wm. O. Crosby (D. C. Heath & Co.) try to identify 
them. 
All soil is composed of disintegrated or decayed rock. 
And it has been observed that the soil of northern North 
America is foreign to the bed-rock. Therefore it must 
have been transported from some other place. The 
glacier did this huge piece of work. The soil of southern 
United States contains no boulders or cobblestones and 
has been formed by the disintegration and decay of rocks 
in place. 
