THE YELLOWSTONE NATIONAL PARK 61 



There were giants in those days. The largest 

 of the standing opal and agate stumps and pros- 

 trate sections of the trunks are from two or three 

 to fifty feet in height or length, and from five 

 to ten feet in diameter ; and so perfect is the pet- 

 rifaction that the annual rings and ducts are 

 clearer and more easily counted than those of 

 living trees, centuries of burial having brightened 

 the records instead of blurring them. They show 

 that the winters of the tertiary period gave as 

 decided a check to vegetable growth as do those 

 of the present time. Some trees favorably lo- 

 cated grew rapidly, increasing twenty inches in 

 diameter in as many years, while others of the 

 same species, on poorer soil or overshadowed, in- 

 creased only two or three inches in the same 

 time. 



Among the roots and stumps on the old forest 

 floors we find the remains of ferns and bushes, 

 and the seeds and leaves of trees like those now 

 growing on the southern Alleghanies, — such as 

 magnolia, sassafras, laurel, linden, persimmon, 

 ash, alder, dogwood. Studying the lowest of 

 these forests, the soil it grew on and the deposits 

 it is buried in, we see that it was rich in species, 

 and flourished in a genial, sunny climate. When 

 its stately trees were in their glory, volcanic fires 

 broke forth from chasms and craters, like larger 

 geysers, spouting ashes, cinders, stones, and mud, 

 which fell on the doomed forest like hail and 



