M. I. Goldman — Catahoula Sandstone of Texas. 261 



Art. XVII. — Petrographic Evidence on the Origin of the 

 Catahoula Sandstone of Texas ; by Marcus I. Goldman. 



Contents : 



Page 



Description 262 



Undisintegrated rock 262 



Macroscopic examination 262 



Hand lens examination _ _ 262 



Disintegrated rock 262 



Mechanical analysis 262 



Quantitative results 263 



General character of products 264 



Microscopic examination 264 



Eounding of the grains 264 



General appearance 264 



Proportion of rounded grains present 264 



Lower limit of rounding 264 



"Ratio of feldspar to quartz 265 



Weathering of the feldspars 265 



General appearance __ 265 



Eatio of fresh to weathered feldspars 265 



Eatio of different species of feldspar to 



each other 266 



Heavy minerals 266 



Proportion of heavy minerals 266 



Species of heavy minerals present and 



their relative amounts 267 



Interpretation 267 



Sizing.... 267 



Eounding 271 



General character ._ 271 



Lower limit of rounding 271 



Proportion of rounded grains present 273 



Eatio of feldspar to quartz 273 



"Weathering of the feldspars'. 274 



General appearance 274 



Eatio of fresh to weathered feldspars 274 



Eatio of different species of feldspars to each other 276 



Eatio of heavy to light minerals 276 



The species of heavy minerals present and their ratios to 



each other 277 



Packing of the sand _ _ 280 



Bedding 281 



Arrangement of fossils 282 



Clay galls .._ 283 



General character 283 



Distribution 284 



Summary and conclusions 284 



The material used in this study was collected in Trinity 

 County, Texas, by Charles L. Baker. An examination of the 

 specimens with a view to obtaining evidence as to the conditions 

 of origin of the sandstone yields the following results. 



