CARBONIFEROUS SYSTEM. 147 



CARBONIFEROUS SYSTEM. 



The Carboniferous system extends over the largest part of the country ex- 

 amined during this trip, and to it the most of the time was devoted. 



No attempt is here made to separate the Subcarboniferous from the Car- 

 boniferous. In fact I am not certain that the Subcarboniferous formation 

 occurs. The strata of the entire series, so far as I observed them, are con- 

 formable and the fossils found in the lower part of the formation were not 

 characteristic of the Subcarboniferous, but are those which are for the most 

 part embraced in the fauna of the coal measures. I am certain, however, 

 that there is a section at least 400 feet thick, lower than the strata of the coal 

 measures which are found in the northern part of the State. 



The Permian formation was clearly distinguished overlying the coal 

 measures on the west. 



The general dip of the strata of this system is to the northwest at about 30 

 feet to the mile, except near Lampasas, where the dip is to the northeast, 

 which may be accounted for either by the existence of an anticlinal in the 

 western part of Lampasas County, or possibly by faulting. 



The strata of the Carboniferous are composed of limestones, sandstones, 

 clay beds, and shales, with three or more beds of coal. On top of the meas- 

 ures in many places is a bed of conglomerate similar to that found overlying 

 the coal measures in the northern part of the State. 



The measures are about 1600 feet thick, so far as examined, although 

 their upper part was not reached. In many places the strata are so deeply 

 covered up with drift that it was impossible to get a continuous section, 

 and the thickness is therefore estimated by the known dip of the strata, 

 where a section could not be made by actual measurement. Many sections 

 were made at different localities, with the hope of being able to secure a 

 continuous section, but there are gaps that can only be filled by estimates of 

 thickness, based on dip and the distance occupied by the wanting section. 

 Enough, however, has been done to give a very correct idea of this forma- 

 tion, which can be worked out more in detail in the future. 



The Carboniferous limestone was first observed at the mineral springs of 

 Lampasas, where the water issues from a fissure in a blue limestone belonging 

 to this formation. The limestone dips east at an angle of one and one-half 

 degrees.* On the top of the limestone is a yellowish marl which seems to 

 be more disturbed or flexed than the underlying material. The limestone 

 contains such distinctive fossils as Spirifer cameratus, Productus costatus, P. 



*The dips here given are from careful instrumental measurements — frequently of lines of 

 considerable length — by Mr. C. C. McCulloch, Jr. 



