82 BOOK OF A HUNDRED BEARS 



There were three principal reasons for this long 

 isolation. The geological information was such 

 that, whatever mineral deposits might lie below 

 its surface, they had doubtless been rendered 

 inaccessible by vast deposits of lava from the 

 latest volcanic centers known on the continent. 



As a hunting and trapping ground it was 

 unavailable, because of its terrible winters, deep 

 snows, and general inaccessibility at the time 

 when trappers reap their harvest. 



And then, above all, it lay between, and apart 

 from, the great channels of communication between 

 the east and the west. It was an inland Saragasso 

 Sea, about which flowed the early channels of com- 

 merce and communication without ever crossing it. 

 On the northwest, one great trail led up the Missouri 

 and down the Columbia — the route of Lewis and 

 Clarke. On the south, through the North Platte 

 and across the divide, where is now Ogden, went 

 another great road. But no trail crossed the 

 Yellowstone. Occasionally, a wandering trapper 

 touched its rim, saw nothing to tempt, and left 

 it unexplored. 



