REVIEWS 377 
sculpturing by mountain glaciers at high and at low levels is clearly 
brought out. The recession of cirques is the principal process at high 
levels, while at low altitudes the deepening of valleys and characteristic 
deposits are the resulting features. A distinction is drawn between high 
altitude and high-latitude sculpturing. The glaciers in the former 
location are located on high mountains and therefore have steep gradients 
which is not necessarily the case for high-latitude glaciers. 
In the large polar areas where inland ice is the characteristic form of 
glaciers, the Arctic and Antarctic each have their own characteristics, 
which are widely different. The north polar region is largely a sea 
indented on its margins by projecting land masses, while the south polar 
region is a continent surrounded by ocean. In the Arctic region the ice 
is less in areal extent than the land on which it rests, and the bergs 
derived from the glaciers are relatively small in size because they are 
calved in narrow fiords, and they are composed of solid glacier ice. 
The contrast to these characteristics is found in the Antarctic region 
where the ice extends beyond the margins of the land into the sea, where, 
with augmentation by snow, there is formed the extensive shelf ice of 
which the Great Ross Barrier is an example. Because of the accumula- 
tion of snow on this shelf ice the surface is very level, and its upper part 
is, therefore, composed of soft ice. Any solid or glacier ice present is 
below the water level. The bergs from this extensive shelf ice are 
characterized by their immense size, their rectangular shape, and their 
white porous ice. 
All the evidence for the alimentation of the extensive fields of inland 
ice seems to show that augmentation of material is largely along the 
margins; not that the snow falls there, but that the constant winds 
radiating outward from the interior carry in a large measure all the 
snows with them, and it does not become lodged until the margin is 
reached. 
The volume is attractive for its large number of illustrations, and to 
the student of glaciers, for its comprehensive list of references, which, 
unfortunately, are grouped at the end of each chapter, necessitating the 
awkward suspense of turning pages to find them. Au Bark. 
The Road Materials of Washington. By HENRy LANDES, assisted 
by OLAF STROMME and CLYDE GRAINGER. Wash. Geol. Sur- 
Vevapulle 2s Olympiaarore, sPp, 204; figs. 51;ipls. 17. 
In a survey of the state for road materials, the accessibility to trans- 
portation, quantity, quality, and local demand were the principal factors 
