Klamath Mountains^ California.— Hcrshey, 147 
by boulder-strewn flats elevated from 10 to 50 feet above the 
creek, which latter continues to occupy a narrow but now 
shallow caiion. Here begin the well marked evidences of 
glaciation which I had formerly considered as indicating the 
Hmit of the glacier. The scanty glacial deposits observed be- 
low this point contain very few granite boulders. From here 
to several miles up the valley the glacial deposit is character- 
ized by abundant granite boulders, and there is otherwise a 
greater variety of rock species, and in other respects, also, the 
deposit is one more nearly typical of glacial action. From this 
point up granite erratic boulders occur on the slopes of the 
mountains. The glacial nature of this deposit is so glaringly 
evident that I recognized it immediately upon coming into 
the region, but the evidences of glaciation farther down the 
valley are so obscure that I have crossed some of the principal 
deposits frequently for several years without recognizing 
their character. 
The newer glacial deposit is essentialh' continuous, and 
presents glacial topography, very slightly modified, and then 
only along the stream courses, by erosion. The area of the 
older deposit shows erosion topography and a very patchy 
glacial deposit. Its discontinuous character may have been 
original, but we know that erosion has been active and long 
continued in its area and the changes have been great. 
I am not prepared to assert that there was an intermission 
of glaciation — an "interglacial stage" — ^between the maximum 
extension of the glacier and its final disappearance. There 
is no clear evidence of it. But some significance must attach 
to the rather remarkable contrast in the matter of granite 
boulders above and below the point one and one-half miles 
from the mouth of Union creek. The source of these boulders 
is a granite mountain at the head of the valley. Perhaps at the 
time of the maximum extension of the glacier, the granite 
mountain was pretty completely buried under snow and sub- 
sequently when the glacier was less extensive, granite frag- 
ments could more readily shower down on to its surface and 
be carried to the end. But the sudden cessation of granite 
boulders in abundance may mean more ; it may tell of a radical 
change in the conditions of glaciation, perhaps even an in- 
termission. 
