Study of Rocks. 
27 
of thought in it more than in any other lowly feature 
of all the landscape. For a stone, when it is examined, 
will be found a mountain in miniature.” We can even 
go further and say that by the use of the microscope 
it is possible to discover much concerning the minute 
structure of rocks, and from that structure to learn a 
good deal as to their mode of origin. When Sorby 
first cut thin slices of rock for the microscopes, he was 
Fig. 5. — Hawkosbury Sandstone near Sydney, showing the effects 
of Marine Erosion. 
met with the reproach that it was impossible to look at 
a mountain through a microscope. In the same way 
it is often said that it is hardly possible to learn much 
from hand specimens of rocks. We shall see further 
on what may be learned from the bare examination of 
a piece of sandstone. In referring to the more minute 
structures in rocks, Sorby says: “Some geologists only 
accustomed to examine large masses in the field may, 
perhaps, be disposed to think the objects so minute as 
