TO JUNCTION OF GRAND AND GEEEN EIVERS. 43 



ages they have served as hinges upon which the great plates of the earth's crust 

 turned, as, in repeated elevations and depressions, the angles which they inclose have 

 been ever varying. 



The following detailed sections of the Carboniferous strata, exposed in the hills 

 immediately back of Santa Fe, will be read with interest by all those who are familiar 

 with the Carboniferous rocks of the valley of the Mississippi. 



Section of strata at Santa Fe. 

 No. 1. 



Feet. 



1. Soft reddish-yellow conglomerate 



2. Red shale and sandstone, without fossils 45 



3. Yellow magnesian, shaly limestone, containing large numbers of Orthisina 



iimbraculum and Productus semireticulatus 



4. Red and yellow shale without fossils 25 



5. Red and yellow argillaceous shale, with thin bands of ferruginous sandy lime- 



stone 20 



6. Yellow and pink shale, with bands of calcareous nodules 8 



7. Yellowish-pink (flesh-colored) limestone, containing Productus nodosus, Spirifer 



cameratus, Retzia mormoni, &c 7 



8. Red and yellow shale, with layers of limestone nodules 15 



9. Yellow limestone, with partings of shale 6 



10. Soft red shales, with two bands of intensely hard, grey, quartzose, fine con- 



glomerate, with numerous but obscure impressions of stems of plants. ... 45 



11. Yellowish-blue compact limestone, with Productus semireticulatus, Spirifer cam- 



eratus, etc., in great numbers 



12. Purple, pink, and yellow shales, with thin bands of ferruginous limestone, con- 



taining the same fossils as the bed above 50 



13. Coarse, brown, sandy limestone, full of crinoidal columns 16 



14. Coarse, gray saiulstone - 5 



15. Gray clay 3 



1 6. Coarse, reddish sandstone 7 



17. Coarse, massive, silicious sandstone, with large grains of quartz, containing 



Spirifer cameratus 10 



18. Gray clay 



19. Gray limestone, with Productus semireticulatus, P. nodosus, &c 8 



20. Pinkish and variegated sandstone 12 



21. Gray limestone 4 



22. Ferruginous and micaceous sandstone 6 



23. Ferruginous foliated limestone, with Orthisina iimbraculum, Spirifer cameratus, 



Athyris Roysii 7 



2 I. Reddish-gray, compact limestone, with Spirifer cameratus, S. lincatus, Prodiic- 

 tus nodosus, P. Puogcrsi, P. scabricidus, P. semireticulatus, Atlujris snlitdita, 

 &c . . 5 



