710 REVIEWS 
consists of kersantite of complex composition; the Gray Mountain 
mass and connected sheets consist of andesite and andesite-porphyries. 
The Mount Holmes bysmalith, Gallatin River laccolith, and the Bun- 
sen Peak mass are composed of dacite-porphyry. 
Chapter three deals with Electric Peak and Sepulchre Mountain, 
which are described as parts of a Tertiary volcano faulted across the 
neck with a vertical throw of more than 5000 feet. The deeper parts 
of the volcano consist of sedimentary strata cut by dikes, sheets, and 
the stock or conduit of the volcano. The ejected breccia and lava 
flows, along with the upper portion of the conduit, make up Sepulchre 
Mountain. The andesitic lavas of Sepulchre Mountain change to 
diorites and porphyries in Electric Peak. Rocks with the same chemi- 
cal composition in one place crystallize into diorites and in another 
place form andesites. Both types are illustrated by photomicrographs 
and photographs. Maps and section illustrate fully the relations of 
the different rocks. 
The northern end of the Teton range, which occurs in the southern 
part of the park, is described at length in the next chapter. This range 
is made up of a nucleus of crystalline schists and gneisses, which are 
overlain by flexed and faulted Paleozoic and Mesozoic strata. ‘The 
eroded edges of these old sedimentary rocks were covered witb vol- 
canic basic breccias and after another period of erosion an extensive 
outflow of acidic lava covered the whole area and still conceals the north- 
ern extremity of the Teton Mountain. 
Mr. Hague, in chapter five, describes the irregular diversified moun- 
tainous area known as Huckleberry Mountain and Big Game Ridge. It 
lies in the southern part of the park and in the Forest reservation and 
consists of a number of northwest-southeast ridges, composed mostly of 
Mesozoic rocks. ‘The Cretaceous sandstones are the prevailing rocks, 
but small areas of older strata are exposed. ‘The rhyolites of the park 
plateau abut against the slopes of the upturned edges. Besides Huckle- 
berry Mountain and Big Game Ridge, there are other elevations known 
as Wildcat Peak, Bobcat Ridge, Chicken Ridge, and Two Ocean 
Plateau. The principal igneous rocks in the area are dacites, sur- 
rounded by apparently younger rhyolite. In the gorge of the Snake 
River the Madison limestones, Teton sandstones, Ellis limestones, and 
shales are exposed. ‘The Snake River hot springs occur near the con- 
tact of the rhyolite with the limestones. The travertine deposits 
around the springs resemble those around the Mammoth Hot Springs 
