Caballos Novaculite and Maravillas Chert, undivided

Caballos Novaculite and Maravillas Chert, undivided
State Texas
Name Caballos Novaculite and Maravillas Chert, undivided
Geologic age Late Ordovician; Mississippian; and Devonian
Lithologic constituents
Major
Sedimentary > Chemical > Novaculite (Bed)
Sedimentary > Chemical > Chert (Bed)
Minor
Sedimentary > Carbonate > Limestone (Bed)ls. interbedded w/ chert nodular to bedded
Comments Orig. ref.: Udden, Baker, and Boise (1916) named units in Brewster Co. in Horse (Caballos) Mtn. and Maravillas Gap, respectively. (following from Emory Peak--Presidio Sheet, Geol. Atlas of Texas, 1979) younger to older: Caballos Novaculite includes 5 members: (1) Upper chert mbr, gray to green, dull lustered, translucent, some siliceous shale, 85-150 ft thick; (2) Upper novaculite mbr, fr. top down--novaculite, white, massive, shattered 35 ft thick; chert, thin bedded, brn and gray banded, some blk., white, and pale green bands, 117 ft thick; chert, irreg. bedded, beds 1-12 inches, lt. brn 40 ft thick; chert, lt. brn-gray, somewhat banded, beds 1-18 inches, 70 ft thick; and at base novaculite, beds 1-4 ft, 83 ft thick; thickness of member 200 to 345 ft; (3) Middle chertmbr covered ant hills show fragments of green to greenish gray, fissile, shale, 34-90 ft thick; (4) Lower novaculite mbr lt.gray, porcelaneous, shattered, weathers white forms low redge, 17-57 ft thick; (5) Lower chert mbr mostly covered, lt. gray, moderate to dk. red, brnish yellow, in part translucent, beds 1-4 ft, thickness 24 - 33 ft. Thickness of formation 411 to 619 ft. Maravillas Formation-- limestone and chert; limestone fine to medium grained, medium dk. gray to grayish blk, interbedded with chert, nodular to bedded, black, most abundant near middle and in upper part; thickness about 300 ft
References

Udden, J.A., Baker, C.L., and Boise, E., 1916, Texas Univ. Bur. Econ. Geology and Tech. Bull. 44 p. 39.

Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.

Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.

NGMDB product
Counties Brewster