THE BUILDING OF THE COLORADO ROCKIES 



241 



But as any corrections for these qualifying factors on the basis of 

 present information would be essentially arbitrary, they will be 

 passed over for the present. Corrections to cover them can, 

 however, be introduced at any subsequent time if the necessary 

 information should become available, or if it should be felt that 

 these factors are of sufficient quantitative importance to justify 

 their further consideration. 



Fig. 12. — Diagram to illustrate the method of calculating the depth of a folded 



block. 



a = the present horizontal length of the section 



b = the shortening caused by the folding 



c = the upbowing resulting from the folding 



a;=the depth of the deformed block 



Then {a-\-b)x = a(x+c) 



ax-{-bx = ax-\-ac 



ac 

 x=—- 



b • 



Using the method above outlined, the thickness of folded shell 

 was calculated separately for each ten-mile sheet of the Lyons- 

 Grand River section. The results were as follows: 



Miles 



No. I. Lyons sheet (westernmost 7 miles) ... 13 



No. 2. St. Vrain sheet 34 



No. 3. Allen's Park sheet 48 



No. 4. Continental Divide sheet 45 



No. 5. Granby sheet 20 



No. 6. Sulphur Springs sheet ...... 26 



No. 7. Troublesome sheet 54 



No. 8. Gore Range sheet 87. 



No. 9. State Bridge sheet 35 



No. 10. Castle Peak sheet ....... 81 



No. II. Gypsum sheet • . 84 



No. 12. Dotsero sheet 88 



No. 13. Glenwood Springs sheet 107 



