10 
NATURE STUDY. 
The Study of Rocks. 
BY GEORGE I. HOPKINS, 
“ We wound 
About the cliffs, the copses, out and in, 
Hammering and clinking, chattering stony names 
Of shale and hornblende, rag, and trap, and tuff, 
Amygdaloid and trachyte.”— Tennyson. 
To most people a rock is simply a rock, unsightly, uninter¬ 
esting, and ordinarily in the way. To the traveller along the 
highway rocks are only so many vexatious obstructions to easy 
and comfortable progress. To the farmer they are, for the 
most part, hindrances to rapid and economical tilling of his 
land. Few, indeed, think of their presence otherwise than as a 
nuisance, or, on occasion, as a convenient missile, excepting, 
of course, the gems, the ores, and quarried rock for building ; 
and fewer still realize that the mud and sand and soil was once 
a part of solid rock, just like the ugly, heavy, cumbersome 
things they see every day. 
It is not difficult, however, to arouse a deep interest in many 
of the common rocks, if the right method be adopted. The 
statement that a certain boulder did not originate in the vicin' 
ity where it lies, but once formed part of a ledge many miles to 
the northward, rarely fails to elicit inquiries respecting its his¬ 
tory, characteristics, resemblances to other rocks, etc., and usu¬ 
ally results in a permanent interest being aroused. The break¬ 
ing open of a pebble or boulder, and its examination with a 
magnifying glass will usually reveal its crystalline texture suffi¬ 
ciently to lead to inquiries and a further examination of it. An 
interest thus aroused is likely to become contagious and devel¬ 
op into a real enthusiasm. 
The writer once succeeded in getting to the railroad station 
a cross section of a wide and deep glacial groove. While wait¬ 
ing fouthe early morning train that was to convey him and the 
rock to his home, a farmer came up and looked the rock over, 
noticed the groove, and felt its polished surface. For some 
