|Name||Caballos Novaculite and Maravillas Chert, undivided|
|Geologic age||Late Ordovician; Mississippian; and Devonian|
Sedimentary > Chemical > Novaculite (Bed)
Sedimentary > Chemical > Chert (Bed)
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|
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.