538 



BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



17. 



16. 

 6019/- 



13. 



8019^-12. 



6019c- 



Oligocene — Continued. 

 Culebra formation — 



18. Lignitic shale bed at base of limestone 



Dark, well laminated, very friable, carbonaceous 

 shales and clays with dark, granular, tufaceous 



material. Fossils at base 



Light colored, sandy limestone. Thickness 1£ 



Dark, very friable shales and tuffs. Fossils abun- 

 dant, Lepidocyclina chaperi. Thickness 3 



a. Light colored sandy limestone to limy sandstone. 



Thickness 1£ 



15. Dark, friable shale, clay and tufaceous material with 

 some thin layers of limy sandstone in the upper 



part 



6019e-14. Thin-bedded, light-gray to cream-colored limy 

 sandstone with some partings of light-colored clay, 



Orbitolites, etc 



Fine-grained, very friable, dark-gray, tufaceous 



material, well stratified 



c. Grayish-green, limy, tufaceous sandstones 



b. Dark, carbonaceous clays and tuff 



a. Grayish, well-stratified, and very friable tufa- 

 ceous sandstone 



(Total thickness, 7 feet.) 

 60196-11. Dark, well stratified, and very friable tufaceous 

 material; some fossils. Turritella, Area, Car- 



dium, etc., Orbitolites 



6019a-10. Grayish, rather nodular, impure limestone, contains 

 some green particles; Lepidocyclina canellei waa 



collected in this bed 



Lignitic shale bed maximum. . 



Dark-gray carbonaceous clays, friable shales and 

 tuffs, some lines of limy nodules parallel to the 

 bedding. Some of these concretions are as much 

 as 6 inches thick and a foot long, their longer 

 axes parallel to the bedding. One or two regu- 

 lar lines of these nodules near base 



Very friable lignitic shale bed maximum. . 



Dark-gray carbonaceous clays, friable shales and 

 tuffs. Lenses of limy nodules parallel to bed- 

 ding, same as (8) 



c. Just below the second line of nodules in these (6) 

 beds fossils were found as follows: Area, Ostrea, 

 Pecten, Spondylus, etc. Among the fossil cor- 

 als are Orbicella, Siderastrea,. and Goniopora; 

 one Siderastra head measured 20 inches high by 

 24 inches in horizontal diameter. 

 6. A few feet below (c) found numerous cerithiids, 



Nassa, and Corbula. 

 a. In the lower layers of this member of the section 

 (No. 6) were found some poorly preserved mol- 

 lusks, such as Area, Cardiurn, Tellina, Venus, 

 and fragments of crab claws in calcareous nod- 

 ules. 



9. 



6020c 



60206 



6020a 



Feet thick. 



30 



10 



30 

 3 



