80 ROMANCE OF GEOLOGY 



In the Foot Hills and plains occur two higher beds ot the 

 Laramie : 



The Willow Creek Beds ... 450 ft. 



And Porcupine Hill Beds ... 2,500 ft. 



I know of nothing in the story of our planet more strongly- 

 fitted to impress our imagination than the study of the changes 

 which this part of the Continent of North America has undergone 

 since the beginning of the Cretaceous epoch. The great Chalk 

 age opens with land ever sinking, but still bright with island spaces, 

 covered with exquisite tropical vegetation, cycads and ferns, 

 sequoias, and magnolias. Luxuriant forests grow and are sub- 

 merged ; the rapid sedimentation of the period fills up the 

 shallow salt-water lakes, another forest appears upon the same site, 

 and this process is repeated (through, who knows what countless 

 thousands of years !) till the remains of seven or eight such forests 

 are found one above the other. Then a period of violent volcanic 

 eruption sets in, which could leave behind rocks 2,000 feet in 

 thickness, but which could not move the Cambrian and Devonian 

 strata from their deep graves beneath the earth ; this was to be 

 done by a far more terrific convulsion. 



Over this desolate plain of dust and ashes a wide sea rolls in, 

 and stretches from the Great Lakes to the furthest limits of the 

 Continent. Slowly again, after vast ages, the land rises ; fresh 

 water lakes and marshes appear. Then commences another deep 

 sea period, succeeded by the Laramie formations, where brackish 

 and estuarine conditions prevailed. This slow and apparently 

 peaceful rising of the land was followed by that tremendous out- 

 break of the central fires, which tore up the Cambrian and 

 Devonian rocks from their abysmal depths in the bowels of the 

 earth, and flung them fifteen thousand feet into the air. In 

 mountainous masses the older rocks were hurled on the top of the 

 Cretaceous, which for untold ages had accumulated ])eaceably 

 above them. 



The massive limestones were crushed, torn, contorted, flung 

 about, as a child would fling hands full of sand, the strata in many 

 places standing absolutely up on end. Then the scene changes 

 to one of comparative calm ; the landscape is luxuriant with the 

 beautiful semi-tropical Miocene flora, with its sequoias and cycads, 



