206 GEOLOGY. 



bed two feet thick. Here are found marine and fresh water shells. 

 About 100 feet from the top, in a dark gray sandstone filled with 

 leaves and stems, Bannister, and afterwards Cope, exhumed the 

 body of a Dinosaur (Agathaumus sylvestre). Four species of Dino- 

 saurs have also been described by Leidy, from the Judith beds 

 (Laramie) in Montana. Still. others, from this same group in Col- 

 orado, have been described by Cope. 



It is therefore a fact that a Cretaceous vertebrate fauna flourished 

 during this Laramie epoch. According to Lesquereux and New- 

 berry, a Tertiary flora existed here at the same time, as we have 

 already seen. Cope, summing up the evidence, remarks: "There 

 is, then, no alternative but to accept the result that a Tertiary Flora 

 was contemporaneous with a cretaceous fauna, establishing an uninter- 

 rupted succession of life across what is generally regarded as one of 

 the greatest breaks in geological times." "The appearance of 

 mammalia, and sudden disappearance of Mesozoic types of reptiles 

 in the immediately next epoch, may be regarded as evidence of mi- 

 gration, and not of creation. Lizards, tortoises and crocodiles, con- 

 tinue from the Mesozoic through the Tertiary to our own time, 

 without great modification of structure. The Dinosauria, how- 

 ever, disappeared from the land, exterminated by the more active 

 and intelligent mammal. Herbivorous reptiles, like Agathaumas 

 and Cienodon, would have little chance in competing with the 

 powerfully armed mammals of Tertiary times. This transition 

 series, therefore, of Hayden, is such in fact as well as in name, and 

 Paleontology demonstrates his conclusion " that there is no real 

 physical break between the well marked Cretaceous and Tertiary 

 Groups." This rich Tertiary flora and Cretaceous fauna flourished 

 then during this epoch also over the plains and in the lakes of Ne- 

 braska. 



COAL IN THE CRETACEOUS. 



No question about the Cretaceous in Nebraska is more frequently 

 asked than this: Is there coal in workable quantity in any of the 

 groups of this period in Nebraska? There is no question about 

 the Cretaceous in the mountains being coal bearing. On this sub- 

 ject, Clarence King observes*: " In the extreme western exposures 

 in the territory of the Wasatch and Uinta ranges, coal beds appear 

 at the very base of the series, immediately upon the capping mem- 

 bers of the Jura; and from that horizon to the summit of the series, 



*Systematic Geology, p. 539. 



* 



