M. I. Goldman — Catahoula Sandstone of Texas. 281 



sands are loose when newly deposited but become more com- 

 pacted under the pressure of overlying dune material. 

 Examples of his figures are : 



For deeper-lying dune sand : pore space is 3*7 *5 per cent. 

 For near-shore marine sand : pore space is 43*0 per cent. 

 For beach sand : pore space is 35*0 per cent. 



The limits of pore space for spheres of uniform size have been 

 shown theoretically to be 25'9 to 47*64 per cent.* Noetling, 

 and more fully Atterberg, both point out that these theoretic 

 quantities are of little significance in nature where sands are 

 neither spherical nor of uniform size ; and the variability in 

 these two elements ought to be considered in conjunction with 

 the measurement of the pore space for sands deposited under 

 different conditions. It is for Monsen's failure to do this that 

 Noetling, justly I think, criticises his work. I will leave this 

 topic, then, merely with the remark that dune and beach sands 

 are of those which are seemingly a little more likely than others 

 to be open textured, so that, since the Catahoula sandstone 

 appears to be loosely packed it may on that evidence belong to 

 one of those two types. 



8. Bedding. 



The entire absence of any lamination or of thin bedding in 

 most of the specimens collected is a characteristic which is hard 

 to interpret. Comparative data are entirely insufficient while, 

 as in most problems of sedimentation, the factors are so 

 complex that a theoretical analysis is very likely to be set at 

 naught by later observations. Even Walther'sf generalization 

 that "absence of bedding signifies uniformity of conditions of 

 formation" except in its broadest sense requires qualification 

 since it seems likely, for instance, that of material of varying 

 size brought by a current of air or water into a body of water 

 agitated by waves, all below a certain size (that resistant to the 

 maximum prevailing wave intensity) might be eliminated and, 

 thus, that original difference of texture in different layers which 

 constitutes bedding, be destroyed. So we have conditions of de- 

 position that do not meet Walther's requirement of uniformity, 

 the lack of bedding being, in a way, secondary. On the other 

 hand, the transporting agent may be uniform over only a very 

 short time but near its maximum of power and thus form an 

 unlaminated deposit of which at least the greater part will not 



*Free, loc. cit., p. 70 ; Atterberg, loc. cifc., pp. 104-105; Noetling, Fritz, 

 Die Packtmg losen Sandes (Criticism of Monsen), Centrblatt Min. , etc., 1913, 

 No. 21, pp. 681-683. 



f Walther, J.: Einleitimg in die Geologie, p. 641, 1893-4. 



