M. I. Goldman — Catahoula Sandstone of Texas. 285 



Ratio of different species of heavy minerals to each other. 



Pore space. 



Bedding. 



Arrangement of fossils. 



Clay galls. 



General significance. 



Distribution. 



The picture presented by the combination of these different 

 factors appears somewhat as follows : 



A sand Hat, either coastal or inland, containing temporary or 

 more permanent, but in either case small and quiet, bodies of 

 water ; the climate arid and perhaps tropical, with strong winds 

 driving the sand about but not accumulating it characteristically 

 in dunes, while nearby rocky hills or mountains crumbling 

 under the effects of temperature changes constantly add fresh 

 angular fragments to the sand. 



To review the different characters, in the order given above, 

 for their bearing on this conclusion we have, first, the important 

 feature of sizing supporting the assumption of sorting of the 

 sand by wind and probably by strong wind such as prevails in 

 tropical regions, but the sorting probably not as perfect as 

 would result in a region of well-developed dunes. In the very 

 perfect rounding even of grains as small as # 035 mtn there is 

 pretty certain evidence of wind action, while the rather small 

 proportion of rounded grains again indicates that dunes did 

 not prevail here and that new angular material was being con- 

 stantly added. This conclusion is strongly supported by the 

 abundance of feldspar, which indicates moreover that the source 

 of supply of this new material was near by. On the amount 

 of weathering of the feldspars, however, which is one of the 

 most important features for the determination of the climate, 

 the evidence is particularly unsatisfactory. Still I shall accept 

 as working hypothesis the tentative conclusion, arrived at 

 above, that the feldspars were predominantly fresh when 

 deposited. Then we have in them also evidence of mechanical 

 disintegration, that is of arid conditions.* 



The proportion of heavy minerals was seen to lie between 

 that characteristic of normal subaqueous deposits and a desert 

 sand, and to be most like that of dune sands. The negligible 

 proportion of micaceous minerals points to wind action ; the 

 small amount of epidote, and absence of chlorite to absence of 



* As stated above there is no basis, in the condition of the feldspars them- 

 selves, for choosing between arid and glacial climate. I reject glacial simply 

 because all our other knowledge about the period, as well as other evidence 

 presented in this paper, especially that from the heavy minerals, precludes 

 such an assumption. How easy it is to be misled by the feldspars is shown 

 by Mackie's paper on the subject, in which he concludes for glacial con- 

 ditions in formations which are now generally believed to have originated in 

 an arid climate. 



