1882.] 
329 
[Davis. 
result of splits in the earth’s crust, but where can their like be found 
in nature ? They serve best as good examples of the seriously 
misleading effects of exaggerated diagrams. In giving so great 
prominence to the direct effects of dislocation, Desor agrees with 
many of the older school of geologists, but he does not give suffi- 
cient proof of his statements ; so far as they imply gaping fis- 
sures they are amply refuted by Ramsay, 1 but he goes too far in 
the disproof and excludes local disturbances from all share in mak- 
ing any of the Swiss lakes. 
Whitney’s orographic lakes, of which Erie 2 and its companions 
are examples, we should call petrographic instead; they fol- 
low the outcrop of certain formations very closely, but with 
the exception noted above, these basins give no sign of disturb- 
ance or sinking, and seem to be simply lakes of erosion, warping 
and obstruction combined (C. 4). 
Dislocations on fissures are generally given greater prominence 
than is here allowed them in the formation of lake basins, and the 
basin itself is often taken as evidence of the fault required to 
produce it. I believe more caution than is usual might be well 
exercised before admitting the existence' of faults, which are, as 
Favre says, too commonly accepted as an easy way out of a diffi- 
culty. They have undoubtedly in many cases a strong influence 
in guiding a stream in the erosion of its valley, but on the other 
hand some rivers show a marked disregard of fault lines, and in 
no instance can a valley or lake be ascribed to a broadly open, 
gaping fissure, for such fissures do not exist. Plenty of authority 
may be found for difference of opinion on this point, 3 but we note 
here only one statement bearing on the subject in hand. Kin- 
ahan 4 does not claim that valleys and lakes are produced 
by faulting or fracturing alone, but rather by the action of 
erosive agents, such as streams and ice guided by previous 
1 Geol. Soc. Journ., xvm, 1862, 188. 
2 Climatic Changes of later Geol. Times., 16. 
3 Among those who consider the forms of mountain and valley surface largely the 
direct result of disturbance and dislocation and to a less degree the effect of erosion, 
we may name L. v. Buch, B. Studer, Desor, and Hopkins ; See also, Kjerulf, Ein Stuck 
Geographie in Norwegen, Berlin Erdk. Zft., xiv, 1879, 144. 
4 G. H. Kinahan, Valleys and their relations to Fissures, Fractures and Faults, 1875* 
