36 
THE PARALLEL ROADS OF 
long distances, and rectilinear. Indeed, we 
have seen that we have beneath every glacier 
a complete apparatus adapted to all the results 
described above. In the softer fragments 
ground to the finest powder under the incum¬ 
bent mass we have a polishing paste; in the 
hard materials set in that paste, whether peb¬ 
bles, or angular rocky fragments of different 
sizes, or grains of sand, we have the various 
graving instruments by which the finer or 
coarser lines are drawn. Not only are these 
lines frequently uninterrupted for a distance 
of many yards, hut they are also parallel, except 
when some change takes place in the thickness 
of the ice, which may slightly modify the 
trend of the mass, or where lines in a variety 
of directions are produced by the intermittent 
action of separate glaciers running succes¬ 
sively at different angles over the same sur¬ 
faces. The deeper grooves sometimes present 
a succession of short staccato touches, just as 
when one presses the finger vertically along 
some surface where the resistance is sufficient 
to interrupt the action without actually stop¬ 
ping it, — a kind of grating motion, showing 
how firmly the instrument which produced 
