BLOCK FAULTING IN THE KLAMATH LAKES REGION 
DOUGLAS WILSON JOHNSON 
Columbia University, New York 
In the summer of ro15 the writer gathered some physiographic 
data of more than ordinary interest concerning block mountains 
in the Klamath Lakes region of Oregon; but because the data were 
based on hasty observations, he hesitated to publish them without 
further verification. The following winter, learning that Dr. G. K. 
Gilbert planned to visit parts of the Great Basin, I placed my notes 
at his disposal in the hope that he might verify the essential 
accuracy of some of my more hasty deductions. This he has done, 
and I make bold to place my observations on record. In doing so 
I apologize for the incompleteness of the data, but trust that the 
importance of the features observed will compensate in some 
measure for the paucity of description. I desire to express my 
appreciation of Dr. Gilbert’s courtesy in permitting me to quote 
his confirmation of my general conclusions, and at the same time 
to acquit him of any responsibility for possible errors in the follow- 
ing statements. The region discussed is shown on the Ashland 
and Klamath topographic quadrangles of Oregon. 
On emerging from the narrower portion of Anna Creek valley 
and entering the broadly open northern end of the Klamath Lakes 
basin, the observer is at once impressed with the topographic 
indications of block faulting. On the west is the east-facing scarp 
of the Cascade Mountains, not very imposing it is true, but remark- 
ably straight and rising abruptly from the basin floor, strongly 
suggesting a fault scarp in the face of which a number of short 
streams have cut their valleys. The Crater Lake cone is seen to 
rest upon the northward continuation of the supposed fault 
fissure, while farther south another volcano, unnamed on the map, 
occupies a similar position. Such a distribution of volcanoes is 
rather suggestive in connection with the fault theory, and the 
229 
