578 PRINCIPLES OF STRATIGRAPHY 



benthonic forms this hypothesis had to be given up. Nor would 

 the character of the adjacent deposits bear out such an interpreta- 

 tion. The absence of stratification in some parts and the fineness, 

 homogeneity, and uniform character of the deposit give it a loess- 

 like aspect. The fossil echinoderms and other macroscopic organ- 

 isms, which are found at intervals, suggest proximity to the sea, 

 with occasional inundations, though, dead echini tests might readily 

 be blown inland as well. 



The layers of flints in the chalk have a similar rude horizontality 

 to that assumed by the Locssmdnnchen in Pleistocenic structureless 

 loess, and like these are of secondary origin, and not necessarily 

 evidence of stratification. Such an arrangement may express rather 

 the periodic stand of the ground water as suggested, by Potonie. 

 Where regular stratification and an abundance of macroscopic or- 

 ganisms are found, a submarine origin no doubt must be main- 

 tained. 



Dunes of Gypsum. A remarkable type of dune sand has been 

 described from New Mexico. This is the white sand of Otero 

 county which forms a tract of dunes of nearly pure granular gyp- 

 sum covering an area of about 350 square miles. The gypsum sand 

 is derived from the "ribs" of gypsum which rise above the salt flats 

 in successive ridges. These gypsum beds belong to the Red bed 

 series of Permic age. The action of the elements soon breaks up 

 the exposed gypsum crystals into small grains, which are carried 

 away by the wind and piled up into dunes. The salt and alkaline 

 salts forming on the surfaces of the salinas are also driven with the 

 gypsum, but on account of their solubility do not remain in the 

 dunes. (Herrick-22.) 



BIBLIOGRAPHY XIII. 



1. ANDERSON, J. G. 1906. Solifluction, a Component of Subaerial 



Denudation. Journal of Geology, Vol. XIV, No. 2, pp. 91-112. 



2. BARRELL, JOSEPH. 1906. Relative Geologic Importance of Continen- 



tal, Littoral, and Marine Sedimentation. Journal of Geology, Vol. XIV, 

 PP- 316-356; 430-457. 



3. BECHE, SIR HENRY T. DE LA. 1851. The Geological Observer. 



4. BERENDT, G. 1869. Geologic des Kurischen Haffes und seiner Umge- 



bung. Konigsberg. 



5. BLANCK, EDWIN. 1907. Ueber Kalkkonkretionen Landw. Vers., 



Vol. LXV, pp. 471-479. , 



6. CALL, RICHARD E. 1881. Fossils of the Iowa Loess. American 



Naturalist, Vol. XV, pp. 585-586. 



7. CAPPS, STEPHAN R. 1910. Rock Glaciers in Alaska. Journal of Geology, 



Vol. XVIII, No. 4, pp. 359-375- 



