Origin of Mountains. 439 
ously with the same in the case of the Sierra, before the 
Cretaceous era, the Cretaceous beds lying on the Jurassic un- 
conformably. 
These two synclinoria are 400 miles apart. The preparatory 
geosynclinal of the Wahsatch—and probably that of the Sierra— 
took for its completion, supposing it to have begun with the 
opening Silurian, a period at least a fifth longer than the whole 
Paleozoic. 
(5.) At the close of the Cretaceous, another pair of geosynclinals, 
parallel with the coast, but geosynclinals of only Cretaceous 
origin, culminated in synclinoria. 
ne of the Cretaceous geosynclinals was in progress east of 
the Wahsatch, along the whole summit region of the Rocky 
Mountains, in the United States. Directly east of the Wahsatch, 
according to King, the beds are 9,000 feet or more thick; and, 
as Hayden states, they have a great thickness in the Laramie 
Plains, and little less over the upper Missouri region ; so that 
the downward movement was in some parts a profound one, 
* Clarence King has very briefly described the Wahsatch region, as well as the 
country to the west, in the third volume (4to, 1870) of his United States 
Geological Exploration of the 40th parallel; and on page 454, he says: ‘ Subse- 
quent to the laying down of the old Cretaceous system, and of those conformable 
freshwater beds which close the coal-bearing period, another era of mountain up- 
ng 
urred, folding the coal series [Cretaceous and Lower Tertiary] into broad 
undulating rid, general trend of no Hi observes that 
shwater Tertiary and clay, “an immense accumulatio laid 
unconformably over this upturned Cretaccous, and, Miocene era, 
were su to ‘ orogra disturbance and “ til e of 15° to 20° 
or thrown into br dulations wherever they lie in the n or- 
hood of the older ranges suc Wahsatch and Ui : ese disturbances 
15 miles of the Wa in which they 
ws 
oceu witnes: 
of the Rocky Mountain region. Mr. King 1 
question as to the identity of the beds that overlie unconformably the 
folds along the eastern flank of the Wahsatch with the horizontal Tertiary deposits 
of the Green River Basin; and that over this basin between the Green River and 
the overlying horizontal freshwater strata. As stated above, he makes the epoch 
of Cretaceous uplifting to have followed, not the Cretaceous period, but the earli- 
est period of the Tertiary, Eocene beds being, in his view, included with the 
in referred to. ; : 
has investigated with much detail the Green River Basin and the 
Tegion east of it, and years since announced that the Lower Tertiary 
Some parts of the Rocky Mountain region, were tilted at a high angle. He has 
held that all the Coal-bearing strata were Lower Tertiary a but now agrees with 
‘ uy 
