GEOLOGICAL SURVEY OF THE TEREITOEIES. 



141 



Si)ri>igs at Mud Volcanoes. 

 General elevation above sea-level, 7, "75 feet ; boiling-point 198^.5 P. 



d 



Size of spring. 



2 . 



p 



3 

 H 



Time of ob- 

 servation. 



Eemarks. 



1 

 2 

 3 

 4 



5 

 6 



a 





190 

 168 



168 

 126 



156 

 134 



136 



88 



140 

 124 

 140 



182 



94 



, 180 



163 



92 

 148 

 172 

 162 



OF. 

 50 

 50 

 50 

 48 



48 



58 



58 

 58 



58 

 58 

 58 



58 



58 

 58 

 58 



58 

 58 

 58 

 56 





Very tbick mud spring. 



Tbeso springs are in the same basin -with tbe 

 mud-geyser bat entii'ely distinct from it. 



At bead of ravine 250 yards above tbe mud- 

 geyser. 





>3. 35p. m, j 

 4. 55 p. m. .. 



5.00 p.m... 



11.20 a.m... 



11.23 a.m..- 

 11. 25 a. m. .. 



11.30 a.m. f 

 H.aOa.m -^ 

 11. 30 a.m. ! 



11. 45 a. m. . 



11.46 a.m... 

 11.48 a.m... 

 11. 50 a, m . . . 



11. 50 a. m. ( 

 11.51a.m. { 

 11.52 a.m. ( 

 11. 55 a. m. .. 







15 X feet 





ravine at tbe bead. Tbere are here some 

 extinct basins and vents for stream. 



A largo green-snlpbur pool with many cen- 

 ters of ebullition, giving off sulpbui', by- 

 drogen. 



Laveiidci -colored spring containing alum. . 



Yellow -sulpbur spring about fourteen feet 

 from Ko. 7. 



Tbis group is in ^a ravine near the Giant's 

 Caldron. No. 9 is on tbe edge of No. 8, and 

 has clear water with confervoidea Imiug 



3 feet diameter 



12 X 20 feet 



9 



60 X 20 fept 



10 





11 



3 X 1 feet 



12 

 13 



Grotto, 3 feet bijrh, 8 feet 

 wide, 20 feet deep. 



30 X 15 feet 



tbe stream. 



Tbe grotto is an opening into a sandstone 

 rock at tbe bead of a small ravine. The 

 top of the entrance resembles a gotbic arch 

 coated wi lb moss and iron. Steam escapes 

 in pulsations. 



A greenish alum pool. 



A pool a few feet above No. 13. 



Light-gray mud spring 10 feet deep. There 

 are others too deep to get temperature. 



Sulphur springs. 



Mud spring. 



14 





15 





16 

 17 ?i 



1? 3 ; 



10 ■ 



Pool. 500 X 60 feet...... 



Small boles, 1 ineb di- ) 

 ameter. 3 



I 





CHAPTER IV. 



GEYSEE-BASIXS OF FIRE-HOLE RIVER. 



We left Mud Volcanoes on the 13tli of August and started for the 

 lower geyser-basin of Fire Hole River. Our course at first led us 

 up an open valley that once formed i^art of the ancient bed of Yellow- 

 stone Lake. At the head of the valley we struck our eld trail of last 

 year, which we followed until we reached the east fork of the Fire-Hole 

 River. The divide between the Yellowstone River and the Fire-Hole 

 River at this i^oint is 8,164 feet above sea-level. The summit seems to 

 be made up mostly of obsidian, which is all porphyritic. The timber is 

 so thick that it is difficulf to trace the connection, but, as we descend, we 

 come across trachytes that seem to underlie the obsidian. It is very 

 compact and porphyritic, containin'g crystals of sanidine. The general 

 color is a light blue, approaching violet. It is through these trachytes 

 that the headwaters of the Madison cut their channels. Near the sum- 

 mit, on the Madi.son side of the divide, there is an old hot-spring basin in 

 which the springs are now 8" extinct, although there are a great many 

 steam-vents from which steam still escai)es; these vents are lined with sul- 

 phur. Besides sulphur the deposits consist mainly of silica and iron. 

 The descent from the divide is very steep and rocky, and through thick 

 timber, a great deal of which is dead and fallen. The valley of the east 

 fork of the Madison oi Fire-Hole at the point we reached it is very 



