374 
GEOLOGY OF THE FOURTH DISTRICT. 
demonstrative proof of the recent effects of streams upon their beds ; examples such as will 
make us hesitate before we decide that such effects as deep gorges can not be formed by 
running streams. 
The few lateral streams that flow into the Genesee, in its course through these gorges, 
give evidence of the same recent origin in the channel. The streams either fall over the 
vertical edge of the cliff, having worn it back to some little extent; or they come in through 
lateral channels, with vertical sides, scarcely disturbing the continuity of the cliff, any more 
than if a deep cutting had been excavated by artificial means. The appearance of both the 
main channel and the lateral one, respectively attest their modern origin. 
Entrance of Wolf creek into the Genesee above St. Helena. From a sketch by Mr. E. N.Horsford. 
The entrance of Wolf creek into the Genesee offers a good example in point. The lateral 
channel is, at its entrance, a square cut gorge of nearly two hundred feet deep. Farther from 
the river, however, the stream appears to have flowed in the bottom of an ancient shallow 
valley, before it excavated the present gorge. Such is doubtless the fact in other instances, 
where there has been a sufficient depression upon the surface to give direction to the water, 
after which it has cut its own channel far into the strata beneath. 
