138 
Journal of the Mitchell Society 
[. November 
with the exception of a few references to physiographic 
effects on human life, scattered through its pages, it presents 
physiography as a science associating causes and effects 
clearly and forcibly, thus avoiding the mistake made by 
many who exalt physiographic control at the expense of a 
science deeply interesting for its own sake. 
Any study of the origin of land forms involves the study of 
both air and water, since air is the medium through which 
solar energy is applied to the earth, and water is the greatest 
agent in producing effects on the earth’s surface. Though 
the greater part of the book is given to land forms, still 
273 pages remain for the treatment of the atmosphere, the 
ocean, and the earth’s solar relations. The treatment is 
essentially dynamic, and the movement in the direction of 
the explanation of the origin of the land forms of the earth. 
The reader is led to see these forms in the process of becom- 
ing what they are, and to anticipate the time when they 
shall give way to other forms. The surface of the earth 
becomes a stage where physical forces play their part, now 
in one role, now in another, until the land above the sea is 
reduced to base level, or rejuvenated by elevation to begin a 
similar sequence of events, to enter upon a new cycle. 
The first chapter of the book introduces the reader to the 
chief relief forms of the earth’s crust and the materials out 
of which they are made. This general survey places the 
problem of the land forms well before the student, and pre- 
pares him for the consideration of the agents that have 
shaped them. Then follow chapters explaining and discuss- 
ing the work of the atmosphere, of ground water, running 
water, snow and ice, of waves and currents in the construction 
of shore forms, of vulcanism, and the effects of crustal move- 
ment, or diastrophism. For the first time does the work of 
the atmosphere receiye anything like adequate treatment in a 
text-book of physiography. These chapters are followed by 
a very excellent generalization and summary of the origin 
and distribution of land forms clinching in the minds of the 
students the facts that have been brought out and driven 
home by varied investigations. , 
