post- Cretaceous Mountain-making along its course. 195 



5. This move of the accumulated formations from the Cam- 

 brian to the Laramie, in the latitudes of the Wasatch, was part 

 of a general movement that extended through a length of 

 1000 miles or more from north to south, it including the mak- 

 ing of the mountain flexures and faults in Canada described 

 by Mr. McConnell, and how much farther north, we do not 

 vet know. 



6. If the uplifts were anywhere produced through lateral or 

 tangential thrust, the tangential movement was general. It 

 was thrust from west to east and the reverse, producing sur- 

 face movements according to resisting conditions, the oro- 

 graphic results being greatest where, as Mr. King states, 

 Archaean ranges resisted the movement and so localized its 

 effects. 



The above inferences appear to be warranted by the facts at 

 present known. 



7. And so the Wasatch Range was essentially finished ; 

 seemingly an individual mountain range, but really polygenetic ; 

 first a lofty ridge of Archaean make ; then enlarged by Paleo- 

 zoic additions and changed in level by increased emergence, but 

 without so far as known, any upturning of the beds ; finally 

 after further preparation by sea-border depositions through all 

 Mesozoic time, profound movements completing the process 

 of development, and that also of other ranges both of the 

 plicate and plateau kinds, the Uinta among the latter. 



8. The new ranges and others older, then became the rela- 

 tively stable confines of Eocene lake-basins in the enclosed 

 Rocky Summit region of the United States, the Green River 

 basin, the Wasatch, the Uinta and others, over which subsi- 

 dence and deposition were still continued. 



In the preceding observations on mountain-making along the 

 Rocky Mountain protaxis, I have referred, so far as the territory 

 of the United States is concerned, only to the western branch 

 of the protaxis, or that including the Wasatch Range. The 

 eastern branch, or that of the lofty Front or Colorado Range, 

 also resisted the tangential thrust, like the Wasatch to the 

 west ; but the disturbance resulted only in making out of the 

 Cretaceous and inferior rocks on the east, little foot hills, 500 

 to 1500 feet in elevation over a breadth of 10 to 15 miles. 



An excellent account of the flexures and faults in these hills, 

 illustrated by many transverse sections besides maps and views, 

 is published in the volume for 1873 of the Hayden Expedition 

 Reports, by Archibald R. Marvine, an accurate observer whose 

 early death was a serious loss to American Science. The sec- 

 tions described are from the eastern base of the mountains for 

 some distance north of Denver, between the parallels of 40° 



