170 
IOWA ACADEMY OF SCIENCES. 
Lake Valley is in the southwest part of New Mexico. 
That its limestone is a geological formation of considerable 
geographic extent has been recently demonstrated by the 
finding of the same fauna in localities many miles from 
the original location in Sierra county. Of special interest 
is the fact of the recent discovery of the Lower Burlington 
fossils, such typical forms as Batocrinus suhcequalis (Hall), 
in the Magdalena range, more than 100 miles north of 
Lake Valley. 
Singularly enough, in New Mexico the earliest Carbon- 
iferous strata appear to be followed by the latest terranes 
of that age — the great median section of the Mississippi 
valley being seemingly absent. In other words, the Lower 
Burlington appears to be followed by beds carrying the 
faunas of the Upper Missourian series of the Mississippi 
valley. 
The vertical sequence of the Carboniferous rocks in 
Magdalena mountains in central New Mexico is essentially 
as follows: 
CARBONIFEROUS SECTION IN MAGDALENA MOUNTAINS. 
FEET. 
13. Limestone, blue, t heavily bedded with 
thick shale partings 300 
12. Shale, sandy, greenish 200 
11. Sandstone, greenish, micaceous, soft.. 50 
10. Sandstone, quartzitic, pebbly 60 
9. Shale, dark colored, silicious 50 
8. Limestone, gray, crinoidal 45 
7. Upper Vein. 
6. Limestone, gray, heavily bedded, crinoi- 
dal 30 
5. Limestone, blue, impure, fine-grained, 
siliceous, “Silver Pipe Lime” 8 
4. Silver Pipe Vein. 
3. Limestone, gray, subcryst^lline 60 
2. Contact Vein. 
1. Schist, granite and greenstones, over. . . 1,000 
The early Carboniferous rocks are believed to extend to 
No. 9 of the section; while all above is late Carboniferous, 
It is a noteworthy coincident that the Lower Carbonifer- 
