University of California. 



[Vol. 3. 



canons ; yet it is unable to climb out of its Modern canon and 

 flood the valley floor. At extreme high water the present river 

 erodes the banks, instead of depositing fine alluvium. If this 

 river had an ordinary grade, similar to eastern rivers, it would 

 be half a mile wide, for it drains an extensive territory and is 

 one of the largest streams of the State. It has a width of 60 to 

 100 feet in certain gorges, and 300 to 500 feet in the Orleans 

 Basin. 



There is historical evidence that the river is at present 

 aggrading its channel. Old settlers say that at Orleans the bed 

 has risen five feet, and some say ten feet, in the last half- 

 century. This is wholly due to the abnormal amount of material 

 thrown into the river by the placer miners. It is beyond ques- 

 tion that if left in its natural condition it would be a strongly 

 abrading stream. Under normal conditions, before the river 

 could materially widen its canon it would have to cut to a 

 much lower grade. I do not believe that the deposits of the 

 forty-five-foot terrace, including a broad, sandy flood-plain, 

 could have been formed while the river bad its present high 

 grade. A reasonable increase or decrease of the volume of water 

 would not have materially affected tins problem, because the 

 contrast between the broad valley floor and the Modern canon 

 is too great. Taken in connection with evidence drawn from all 

 parts of the Klamath region, I feel reasonably safe in main- 

 taining that the cutting of the present tiny canon is the result 

 of a Modern tilting of the Orleans Basin, presumably toward 

 the southwest. The forty-five-foot terrace descends at prac- 

 tically the same rate as the present river, and consecpiently this 

 particular period of tilting post-dates the deposition of the ter- 

 race deposits. 



The terraces above the forty-five-foot terrace do not follow 

 the present river grade. At times I have had the impression 

 that the terraces on the south of the river are higher than the 

 corresponding levels on the north of the river, but this is far 

 from conclusive, and will not be discussed. However, it is prac- 

 tically certain that the higher terraces (all above the forty-five- 

 foot terrace) are, 1st, approximately parallel to each other; 2nd, 

 do not materially descend downstream, but, rather, 3d, are 



