GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 125 
torrential plentitude when they come at all. Some explanation 
must be sought for the basins found in the saline areas. It 
might be supposed that such explanation would be found in the 
depressions resulting from the post-Tertiary lava flows which 
occur over the entire territory. To this it may be replied that 
the basalt is certainly of deep origin, for the preceding flows 
were all acid and the basalt overflows are essentially similar 
among themselves and demand a common origin at a depth. 
Moreover the distribution of the flows indicates that the oro- 
graphic lines of weakness opened were of almost continental extent. 
The depressions due to the outflow of basalt would not account 
for the local basins referred to and we are driven to the conclu- 
sion that these slight depressions are due to the effect of the 
removal of the soluble ingredients in these beds themselves. 
The discussion of the economic aspects of these beds will 
occur in the forthcoming bulletin of the University Geological 
Survey of New Mexico. 
Cee AERRICK. 
IDNESCIRIUPINOIN| OM IWATE) 
PLATE I. 
Sketch map of the region of the “ White Sands” including part of Dona 
Ana, Socorro, and Otero counties, New Mexico. 
PLATE U1, 
Mostly Permian fossils from exposures near Tularosa and east of the 
Sandia Mountains in Bernalillo county. These plates are given to illustrate 
the fauna rather than as a basis for a discussion of the species figured, which 
have as yet been subjected to no critical study. 
Fic. 1 Pseudomonotis n. sp. (costatus). 
Fic. 2. Bellerophon sp. 
Fic. 3. Aviculopecten cf. coxanus. 
Fic. 4. Pseudomonotis radialis Meek. 
Fic. 5. Undetermined. 
Fig. 6. Undetermined. 
Fics. 7, 8. Rhynchonella osagensis Swallow. Two views. 
Fic. 9. Pleurotomaria cf. subdecussata Geinitz. 
Fic. 10. Pleurotomaria marcoutana Geinitz. 
Fig. 11. Rhynchonella sp. Two views. (cf. R. osagensis Swallow). 
