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equally as well as many of the imported marbles. Some of these limestones are of such a very fine compact texture that, thej would answer very well as a lithographic rock. Simpson's spring issues from the base of these bluffs by two outlets front the solid rock, which unite and flow in a clear streamlet of suf ficient water to irrigate the neighboring farms of Simpson's creek valley. Near Mr. Hubbard's, on this creek, there is a cha lybeate spring, in which the taste of iron is quite sensible. Large springs occur frequently in the valleys and ravines of San Saba county, many of which aftord sufficient water for irriga ting. At the town of San Saba is a' large spring, having an area of nearly one-fourth of an acre of the clearest water, which gives rise to a large stream and affords a constant supply of water for a good flouring mill, where most of the flour for the county is made. The calciferous sand rock, and the mountain limestone which lies immediately above, are the prevailing rocks of the southern portion of this county. The latter is of great value for its fine marbles and compact limestones, suitable for monumental purposes and for durable architecture. The Tren ton limestone has been recognized in but a few places, the whole needing further examination. It's chief fossils are of the follow ing genera, Belerophor., Maclurea, Orthis, Murchisonia, Pleuro tomaria and others. The reader must bear in mind that we only made a general reconnoisance of this and other portions of the State, and not a detailed survey. The Trenton limestones, including the Galena limestones, both of which are considered as belonging to the same geological period by some of our best geologists, are the series in which such large quantities of lead have been found, and are still being found in the northwestern part of the State of Illinois, Southern Wisconsin, and the north eastern portion of lovya. .The very productive lead mines of. Missouri are in the calciferous sand. rock. We may expect to find lead ore in these rocks, which abound here and in other parts of the State, but which have as yet received a very cursory geo logical examination. The calciferous sand rocks are probably about three hundred feet thick, making the entire thickness of the Potsdam rocks to amount to eight hundred feet, as seen in this and the adjoining counties. JSorth of San Saba river in the same county are some carboniferous rocks, and should coal be found there it could be very easily transported to the great iron region of Llano county. This is so much to be desired that diligent search for coal should be made in that section. About threes miles above the mouth of Pecan Bayou are sandstone hills in massive beds. It is a fine-g vamed, compact
