GEOLOGICAL STRUCTURE OF THE DISTRICT. 
31 
and arrangement of the material was not effected in a body of water, which, indeed 
could hardly have existed within the conduit during the volcanic period. It would 
rather seem to be due to the winnowing action of winds on material thrown into 
the air, to a sorting by rolling down slopes, or to alternations in material thrown 
out by successive eruptive explosions. 
CARBONACEOUS MATERIAL. 
In the Doctor-Jackpot mine, just above level 15, or about 600 feet below the sur¬ 
face, the ore is accompanied by a black coaly material, of rather fragile character, 
which retains an original woody structure. Chemical examination of this material 
by Doctor Hillebrand shows that it is noncoking, gives an oily distillate, and is a 
bituminous coal with the following composition: 
Composition of coal from Doctor-Jackpot mine. 
Moisture. 1.0 
Volatile carbon.. 29. 0 
Fixed carbon. 68. 4 
Ash. . 1.6 
100.0 
Similar material, but with conchoidal fracture and no trace of an originally 
organic structure, occurs in irregular bunches in the breccia on the 550-foot level 
of the Morning Glory mine, particularly near the west end of the Ingham crosscut. 
This is also noncoking and its composition is as follows: 
Composition of coal from Morning Glory mine. 
Moisture... 0.5 
Volatile carbon. 21. 0 
Fixed carbon.:. 69. 9 
Ash.. 8.6 
100.0 
Rickard" mentions the finding of similar coaly material in the Logan mine at a 
depth of 600 feet and of a silicified tree stump in the [Stratton’s] Independence 
mine at a depth of 500 feet. In July, 1905, a carbonized tree trunk was found on 
the 800-foot level of the Elkton mine. A letter from Mr. E. M. De la Vergne, the 
manager of the mine, dated November 25, 1905, states that the log is 18 inches in 
diameter and was at that time exposed for a length of 5 feet. It lies in hard 
unfissured breccia, about 40 feet west of the Elkton basic dike, and the matrix 
shows the impressions of knots and bark. A specimen from this tree trunk, kindly 
supplied by Mr. De la Vergne, retains the rings of growth and other general woody 
structures, although the material is now altered to coal like that found in the 
Doctor-Jackpot mine. According to Prof. F. H. Knowlton the tree was undoubt¬ 
edly a conifer and probably belonged to a species of Pinus. 
In view of these various occurrences there c^n be no question that vegetation of 
the time of the Cripple Creek eruption was buried in the breccias to depths which, 
after erosion, are still to be measured by several hundreds of feet. This fact, more 
a The Cripple Creek volcano: Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 384. 
