96 FIELD CoLuMBIAN MusEUM—GEOLOGY, VOL. I. 
TABLE. OF DETERMINATIONS OF DIMENSIONS OF CRATER. 







METERS. FEET. 
Greater Diameter of Crater. 400 1,312 | Topf, 1886. 
600 1,968 | Felix and Lenk, 1887. 
612 2,008 | Aguilera & Ordofiez, 1894. 
800 2,624 | Dollfus et als., 1865. 
825 2,668 | Sonntag, 1857. | 
1,524 5,000 | Gerolt and Gros, 1834. 
1,600 5,248 | Glennie, 1827. 
Lesser diameter of Crater. 200 656 | Topf. 
400 1,312 | Felix and Lenk. 
400 1,312 | Aguilera and Ordofiez. 
740 2,373. | Dollfus et als. 
1,219 3,999 | Gerolt and Gros. 
Depth of, Crater soi re 150-180 | 492-591 Pieschel, 1853. 
About 250 820 | Dollfus et als. 
Depth from the Malacate 
(Windlass)/o Gee. ee ores 205 673 | Aguilera and Ordofiez. 
Depth from the Brecha Sil- 
ACEO sei tely Ss spel ols ale ea arene aay 50 164 | Topf. 
150 492 Felix and Lenk. 
164 527 | Sonntag. 
244 800 | Gerolt and Gros. 
Depth from the Pico Mayor 60 197 | Topf. 
305 I,oor | Gerolt and Gros. 
S11 1,020 | Sonntag. 
505 1,657 | Aguilera and Ordofiez. 
In the walls of the crater the layers of lava of which it is made 
up are plainly visible, being seen best on the western side. These 
layers do not lie horizontally, but dip at various angles. No layer can 
be traced entirely around the crater by the eye, though obviously each 
flow was likely to have found exit at various points along the rim. 
The layers are separated by strata of volcanic sand, scoria, etc., which 
being more easily eroded than the solid lava, leave the latter project- 
ing from the walls. The interspersion of the loose volcanic products 
indicates that after each lava flow coarse blocks and showers of sand 
were ejected, to be more or less consolidated and cemented before the 
next flow. ‘These loose products have frequently, moreover, been 
further cemented by the lava of the succeeding flow into a firm breccia, 
which forms in some portions of the crater the only layer intervening 
between the more compact lavas. As previously noted, such breccias 
also occur about the region of La Cruz. The lavas about the crater 
vary in color from red to black, according, apparently, to the ‘ets 
of oxidation of the iron. | 
The present activity of the crater is lemited to the exhalation of 
steam from various points in the crater:walls and the floor of the 
crater. Other gases accompany the steam, especially hydrogen- 
sulphide and sulphurous acid, and combining, form sulphuric acid 
