216 B.F. Shumard on the Primordial Zone of Tezas, 
Along the Colorado for some distance above the mouth of 
Brady’s creek and throughout the whole course of the latter 
stream in San Saba county and Deer Creek in Burnet county, 
this formation is characterized by high castellated and mural 
escarpments, which are strikingly similar in their appearance to the 
bluffs of 3d or Lead Bearing Magnesian Limestone of the Osage, 
Gasconade, and Niangua in Missouri and those of the same geolog- 
ical age (Lower Mag pees Limestone) that escarp the upper Missis- 
sippi in sew Wiscons nan ene ota. In the districts drained , 
coated with brilliant crystals of “drazy quartz. The beds are 
pee ae fact they erik all the greteech of the paseo 
strata in Xas, 
Fossils. ate the chert beds of the formation we have found at 
a few localities Pleurotomaria, Ophileta and Orthoceratites identical 
with a miter discovered by Prof. Swallow and the writer in the 
3d Magnesian Limestone of Missouri. No fossils have yet been 
foand in de ‘edeaieta beds of the formation in Texas 
Porspam Sanpstonez, 
This important division of the Primordial zone in Texas h 
a thickness, estimated at not less than five hundred feet. The 
sections given below taken by the writer in Burnet Lora as- 
show the character of the different beds that constitute ie mass. 
Section at a small creek, five miles N.W. of the town of Burnet:— 
No. 1. Soft, chalky limestone pone well marked cretaceous fossils, 50 
ee Orithis | aminserces, Orthis sp. ees — ica and 
ingula sp. 81 ft. 
* 8. Mot et gray, — and release ne ait saleoryilil 
line limestone, with alternating — of — ee 
contains the same fossils as No. 2, + ie 4 
* 4.5) ith ting led f No. - - 55 
a ope wi projec ing ledges of No. ack 
“ 6. Schistose cidetee-textored fiinesiona, made up of es 
line ghee’ and phonuding ase fagens. of tatlobihan, 
chiefly Arionellus, 20 ft. 
