136 Trans. Acad. Sci. of St. Louis. 



of wind-borne dust derived from the adjoining deserts. 

 In the case of the larger example noted it is not to be 

 inferred that since the clays and sands have such an 

 enormous thickness, the waters were in the beginning at 

 least of the same depth, but rather that the arm of the 

 ocean and afterwards the inland sea was always very 

 shallow, and that as the area was filling up with the sedi- 

 ments the waters continued to rest on the surface of the 

 basin rising with the rise of the bottom. 



In the phenomena connected with the filling of the 

 Coon Butte lakelet by "lake deposits" is probably to be 

 found the key to the entire mystery of the formation of 

 the vast Western American "Fresh-water Tertiaries." 



Lower Meteoric Zone in Coon Crater. The bed of 

 coarse materials lying immediately above the basal mem- 

 ber of the section in Coon Crater is especially noteworthy 

 on account of the meteoric fragments which occur so 

 abundantly. This is at a depth below the floor of the 

 crater of about 600 feet. Its formation appears to rep- 

 resent an episode when eolic agencies had full sweep 

 as at the present time, when concentration, as it were, 

 of the large and heavy rock-fragments was going on 

 through the exportation of the finer soil materials-. So 

 soon as a sporadic "cloud-burst" chanced partially to 

 fill the crater, lake conditions prevailed and the process 

 of residual concentration through deflative influences 

 ceased. 



As will be more specially noted hereafter meteoric falls 

 were probaly not more frequent during the time repre- 

 sented by this zone, than during any other period of 

 equal length. In the one case the finer soil particles were 

 constantly removed, while in the other they were rapidly 

 deposited. 



Mineralogic Composition of Canyon Diablo Meteorites. 



The Canyon Diablo meteorites have been described 

 by many writers. Since the first announcement of their 



