xxxii Trans. Acad. Sci. of St. Louis. 



The walls are of distinct masses of broken granite rock, chiefly 

 cubical, the largest near the top of the wall, the smallest at the bot- 

 tom. The edges of these rocks are as sharp as though freshly broken 

 out of a quarry. 



What was the origin of these pits? Two theories have been ad- 

 vanced. One, that it is a great "blow out," i. e., volcanic in nature; 

 the other, that it is simply a glacial deposit. 



As to the theory of volcanic origin, the fact that the fragments tend 

 to be cubical, are sharp angled, the largest lying in the highest 

 places, and the whole structure of the pit being so regular in plan, 

 would strongly suggest a violent local upheaval, due, say, to super- 

 heated steam, since there is nothing in the immediate neighborhood 

 to imply volcanic action accompanied by eruption of lava or ash. 

 Still, close to the Park is Specimen Mountain, which is said to abound 

 in pumice. In the canyon four miles distant huge blocks of rock 

 encumber the valley, having the appearance of having been thrown 

 down from the bordering mountains all at the same time. If by an 

 earthquake, it may have opened a crevice close to Fern Lake, letting 

 water into the depths to be suddenly converted into steam that burst 

 through the granite crust and left these pits to mark the site of the 

 explosion. 



As to the second theory, that of glacial deposit, there is much in its 

 favor. The pits are directly over the course of a glacial stream, at 

 its lower end is the beginning of a great moraine. 



At first glance the pits will call to mind the so-called "kettle holes," 

 so common on the site of moraines. But if the theory of the origin 

 of kettle holes is correct, then our Estes Park cavities can hardly be 

 so classified. For it is supposed that the ice carrying upon its surface 

 the debris that is to form the moraine melts in such a fashion as to 

 cause the transported rock, sand, etc., to slide off and down, gradu- 

 ally forming a ring or oblong with the unmelted ice in the center as 

 a core. This core finally melting, a hollow is left — the kettle. The 

 sides fall in under the wash of rains or from the weight of the loose 

 material, so as to form slopes that may meet to make hollow cones or 

 troughs. 



Now, in the Estes Park pits we have these configurations, but in- 

 stead of a loose, movable material, the walls are of angular rock 

 masses firmly jammed together and altogether incapable of any such 

 sliding movement. 



So far the only solution of this mystery seems to be through a stout 

 derrick and some dynamite, backed by a good working squad, but in 

 the wilderness such aids to research are not readily at hand. 



Dr. H. T. A. Hus spoke on '^Inheritance in Capsella."^ 



* When Dr. Hus read this paper he left it an open question whether 

 new forms of Capsella were to be looked upon as hybrids or as muta- 

 tions sensu de yries. Subsequent observations have enabled Dr. Hus 

 to explain new forms as the result of hybridization. 



