. Annual report. 1st-12th, 1867-1878. Geology. 100 GEOLOGICAL SURVEY OF THE TERRITORIES. long aucl half a mile wide. The deposit now can be seen far out in the deeper portions of the lake, and the bubbles that arise to the surface in various places indicate the presence at the orifice of a hot spring beneath. Some of the funnel-shaped craters extend out so far into the lake that the members of our party stood upon the silicious mound, extended the rod into the deeper waters, and caught the trout and cooked them in the boiling spring without removing them from the hook. These orifices, or chimn
. Annual report. 1st-12th, 1867-1878. Geology. 100 GEOLOGICAL SURVEY OF THE TERRITORIES. long aucl half a mile wide. The deposit now can be seen far out in the deeper portions of the lake, and the bubbles that arise to the surface in various places indicate the presence at the orifice of a hot spring beneath. Some of the funnel-shaped craters extend out so far into the lake that the members of our party stood upon the silicious mound, extended the rod into the deeper waters, and caught the trout and cooked them in the boiling spring without removing them from the hook. These orifices, or chimneys, have no connection with the waters of the lake. The hot fames coming up through fissures extending down toward the interior of the earth are confined within the walls of the Fig, 34. orifice, which are mostly circular and beautifully lined with delicate porcelain. Figure 34 exhibits a fine cross-section of one of these funnel-shaped basins. Wherever the heated water issues from ori- fices at the bottom of the lake the temperature is changed. The deposit of silica along the shore has been built uj) in extremely thin layers, or lamiute, never more than the sixteenth of an inch in thickness. The shore, for several yards in width, is covered to a considerable thickness with the SECTION OF LARGE SFKING, YELLOWSTONE LAKE. disiutegratcd SiHCa, SO tlUlt lU walking over, it seems like treading on the broken fragments of washed shells alona' the sea-shore. Much of the debris has been cemented like the. together, so that there are large masses scattered around, Fig. 35 Florida coquina. The question will arise as to the time that must have elapsed during the deposition of this tliick bed of silica. We may take the position that no new groups of springs break out, or have done so in modern times. Isolated springs connected with groups may form new openings, however. We may, therefore, start from the period of the cessation of the volcanic forces of this region, and trace the history do
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Keywords: ., bookcentury1800, bookdecade1860, bookpublishe, booksubjectgeology
