676 J. A. UDDEK COMPOSITION OF CLASTIC SEDIMENTS 



183. Brown ooze containing 6 per cent organic material, taken 60 miles east 



beyond the continental shelf. Steamer Trenton; Station No. 2715; 

 latitude 38° 29' 30" north, longitude 70° 54' 30" west; depth, 1,753 

 fathoms. 



184. Soft green mud. The sample contains various organic fragments with 



the inorganic, especially among the larger sizes. This analysis is partly 

 estimated. From just below the continental shelf. Steamer Alba- 

 tross; Station No. 2734; latitude 37° 27' 0" north, longitude 73° 58' 0" 

 west; depth, 841 fathoms. October 26, 1886. 



185. Green mud; some is organic, and some concretionary material among 



the larger particles ; taken some 40 miles from land, southwest of the 

 southwest part of British Columbia, outside of the continental shelf. 

 Steamer Trenton; Station No. 2860; latitude 51° 23' 0" north, longi- 

 tude 130° 34' 0" west ; depth, 876 fathom's. August 31, 1888. 



186. Gray ooze from the outer part of the continental shelf, west part of the 



Atlantic. Mud and fine sand, with much organic material, which does 

 not affect the analysis. Steamer Fish Hawk; Collections No. 871; 

 Station No. 2221 ; latitude 39° 5' 30" north, longitude 70° 44' 30" west ; 

 depth, 1,525 fathoms. 



187. Brown ooze, about one-half organic ( Globigerina ) , from 100 miles east 



of continental shelf. Steamer Albatross; Station No. 2712; latitude 

 38° 20' 0" north, longitude 70° 7' 30" west; depth, 1,867 fathoms. 

 September 17, 1886. 



188. Gray ooze, about one-third organic, from south of the continental shelf, 



Aleutian Islands. Steamer Trenton; Station No. 1138; latitude 52° 

 40' north, longitude 166° 35' west ; depth, 2,257 fathoms. July 21, 1888. 



189. Green mud, sand; 120 miles west of south boundary of California. 



Steamer Trenton; Station No. 3627; latitude 32° 44' 0" north, longitude 

 119° 32' 0" west ; depth, 776 fathoms. April 13, 1896. 



190. Gray mud, outside of the continental slope, beyond the mouth of the 



Mississippi River. Steamer Albatross; Station No. 2382; latitude 

 28° 19' 45" north, longitude 88° 1' 30" west; depth, 1,255 fathoms. 

 March 3, 1885. 



WIND DEPOSITS^ 



Classification. — It appears that all materials owing their present posi- 

 tion and mechanical composition to the action of the atmosphere may 

 be referred to some one of fonr categories. These are lag gravels, or 

 coarse residual deposits in the rear of sand dnnes and on desert lands; 

 dune sand; fine sand, accumulating in the lee of drifting dunes, and 

 dust. 



Lag gravels. — In many places where atmospheric erosion is going on 

 streaks of gravel are to be seen partly covering the ground. Most often 

 this gravel forms a thin veneer, which partly protects the ground from 

 further erosion. Though the present position of this material is due to 



*The following summary of descriptions of wind deposits is abbreviated from my 

 earlier paper already mentioned. 



