EPICONTINENTAL SEA OF JURASSIC AGE 265 
question beyond controversy. That there was communication 
between the Arctic and the Pacific is supported by the presence 
of Arctic species in the Pacific fauna. From the distribution of 
the Jurassic sediments as given in the preceding pages it may be 
asserted with a measurable degree of confidence that the con- 
nection between these two bodies of water was during Jurassic 
times as it is today by way of the Bering waters. As the pres- 
ence of Jurassic deposits on the Alaskan Peninsula and the 
Aleutian Islands testify to the submergence of those areas, it 
may be assumed that communication between the two oceans 
was somewhat freer than at present. 
The question which is now brought to mind is whether the 
interior sea had any other connection with the ocean. The 
character of the fauna excludes any hypothesis favoring a 
southern connection either with the Gulf of Mexico or the 
Pacific. If there had been such a connection a southern facies 
would be expressed in its fauna. Such evidence is entirely 
absent. The evidence against any other Arctic connection 1s 
largely negative, but as such is measurably strong. The inves- 
tigations of American and Canadian geologists have failed to 
bring to light any Jurassic deposits in the North aside from 
those already described, although approximately the whole area 
where we should expect to find them has been gone over. 
McConnell,? who made geological investigations in Athabasca 
and along the Finlay and Porcupine Rivers, found Cretaceous 
beds resting on Devonian and Carboniferous strata. The interval 
of time which elapsed: between the Carboniferous and the Lower 
Cretaceous is not represented in this region. 
Spurr? found the same conditions to.obtain for the Upper 
Yukon region of Alaska and the neighboring British territory. 
The Lower Cretaceous rests on Devonian or Carboniferous rocks. 
As before stated this evidence is merely negative. Jurassic 
rocks may have been deposited and afterwards cut away. But, 
* Geol. Survey of Canada, Vols. V and VII. 
2Geol. of the Yukon Gold District, U. S. Geol. Sury., Seventeenth Ann. Rept., 
1897. 
