22 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



it presented a continuous and regular shore line, broken only b}- a single 

 narrow bay, separating the Pike's Peak mass from the mainland, and now 

 known as Manitou Park. On the west, toward the parks, its original out- 

 lines are as yet less certpinly known, but though less regular they probably 

 had a general parallelism with the eastern shore line. North and south this 

 line of elevation was continued by a series of islands and siiljuierged reefs 

 to the Black Hills of Dakota on the one hand and into the present Ter- 

 ritory of New Mexico on the other. 



The Parks. — That the present valleys, known respectively as the North, 

 Middle, and South Parks, have been more or less submerged in Paleozoic 

 and Mesozoic and again in Tertiary times, and that atone time they formed 

 a connected series of bays or arms of the sea, is proved by the sediments of 

 those eras that are still found in them. Although the geology of the park 

 region has not been studied in sufficient detail to afford cotnplete data in 

 regard to its past history, enough is known to furnish its general outlines. 



In some respects the present conditions of these depressions are those 

 that prevailed in the earliest Paleozoic times; in others they have expe- 

 rienced more or less change. Then as now the outlet or opening of the 

 Noith Park was toward the north, of the Middle Pai-k toward the west, and 

 of the South Park toward the south. On the other hand, up to the close of 

 the Cretaceous the North and Middle Parks were connected and formed a 

 single depression; the present mountain barrier between the Middle and 

 South Parks did not extend as far as their western boundaries, and a water 

 connection existed between them, whose outlines cannot now be given 

 exactly, owing to faulting and subsequent denudation; again, the waters of 

 the South Park extended westward to the flanks of the land mass now form- 

 ing the Sawatch Range. It seems probable that in earlier Paleozoic times 

 only the North and South Parks were sufficiently submerged to receive the 

 sediments that were washed down from the neighboring land masses, but that, 

 as time went on, the waters became dee^ier or the sea bottom subsided, so 

 that in Cretaceous times sediments were deposited continuously through the 

 three valleys. In Tertiarj times again, after they had been raised above 

 the ocean-level, fresh-water lakes occupied the parks, and in their basins 



