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pg 016: First report of progress of the Geological and Agricultural Survey of Texas Publication 14212432.

 
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which have such a combination of natural advantages for true enjoyment as are here within a circuit of a few miles.

The Azoic rocks of this section trend north east and southwest, being in the same line of upheavel, as the rocks of the same period in the Ozark Mountains of Arkansas, and the Iron Mountains of Missouri. Garnets are quite common in the granite of Llano, and further explorations will probably bring to light other characteristic minerals of that rock.

PRIMORDIAL OR POTSDAM PERIOD.


The Potsdam strata here lies unconformably upon the Azoic rocks in either horizontal strata or in layers inclined at small angles. Near Honey Creek, and also near the head waters of the Little Llano, it can be seen directly overlying the Azoic metamorphic rocks. It consists of red, yellowish white and grey sand-stones in strata, alternating often with grey limestones of differ ant shades, some of which are nearly white. In Llano county its fossils are more abundant than in either Burnet, Mason or San Saba counties, where including the calciferous sand rock of the same period, forms the larger portion of the rocky strata. It's recognized characteristic fossils are of the following genera : Lingula Bathyurus, Conocephalus, Dicellocephalus, Agnostus, Arionellus, Discina and others, some of which are undetermined. There is a fine exposure of these rocks at the Pack saddle or Llano Mountain, at the west end of which the following section was taken:

1. Surface, dark gray lime stone in thin layers, containing a few crinoids, 68 feet. 2. Red sand stone, 46   3, Hard, gray siliceous lime stone. containing Bathyurus, Lingula and other fossils, 55 feet. 4. Light, blue grayish compact lime stone, 172   5. Soft, yellowish white sand stone, 32   6. Similar to No. 3, 12   7. Reddish brown sand stone, with Lingula and a few other fossils, 326 feet. 8. Granite, mostly covered with soil, and sloping gradually into the valley, 439 feet. 1150 feet.

Numbers three and six are hard, compact siliceous, lime stones highly fossiliferous, tinged with light green spots silicate of lime containing Bathyurus, Lingula, Discina and other fossils.

 

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