104 National Geographic Magazine. 
that flow northward from the Alps, and transect particularly 
thick portions of the upturned marginal conglomerates and sand- 
stones, which he regards as the deltas formed by the same rivers 
at an earlier time, when the mountain folding had not extended 
outward as far as it does now from the axis of the Alps. I have 
suspected that the same kind of evidence might be used to indi- 
cate that the Delaware above Trenton, between Pennsylvania and 
New Jersey, is in part of even pre-Triassic origin ; for where it 
now enters the Triassic belt, there is a particularly heavy and 
coarse sandstone, sometimes conglomeratic. Being a large stream, 
it might persist in an anaclinal course through the northwest- 
ward monocline formed by the Jurassic uplift of the Triassic 
beds, although the smaller streams of the region were then prob- 
ably extinguished, to be replaced by a new system consequent 
upon the new order of things. 
Large rivers, more or less persistent in the face of opposing 
disturbance, therefore appear to be generally recognized; but it is 
noticeable that those quoted from the Himalaya and the Alps 
presumably occupied, at the time of disturbance, well enclosed 
valleys, from which it would have been difficult for them to 
escape backwards or laterally; and that, even if successful in the 
end, they for a time suffered defeat or ponding of greater or less 
extent and duration. There is no evidence that the Green river 
was well enclosed immediately north of the Uinta mountains at 
the time of their first elevation; hence the likelihood of its tem- 
porary ponding or enclosure is increased. 
It is stated by Powell that not only the Green but even the 
smaller streams of the Uintas are of origin antecedent to the 
mountains. He writes: “the explanation of the cafions of Green 
river will assist us in understanding the origin of the lateral 
valleys and cafions. The streams were there before the moun- 
tains were made—that is, the streams carved out the valleys and 
left the mountains. The direction of the streams is indisputable 
evidence that the elevation of the fold was so slow as not to 
divert the streams, although the total amount of elevation was 
many thousands of feet. Had the fold been lifted more rapidly 
than the principal streams could have cut their channels, Green. 
river would have been turned about it, and all the smaller 
streams and waterways would have been cataclinal” (Colorado 
River, 162). 
