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Vol. XV May-June, 1938 Nos. 5-6

F. R. Oberhansley, Junior Naturalist

One mile below the highway between Mammoth and Tower Falls on Geode Creek are a series of interesting bogs. Situated in the bed of an old glacial lake that has been filled with silt and encroaching vegetation is a typical quaking bog. As one walks across this smooth grassy surface, he is impressed with the fact that underneath the thin veneer of grassy sod there is an unknown depth of jolly-like muck. The raft of turf quivers and ripples for a distance of several yards at every stop.

Near the western end of this grassy meadow are several breaks in the turf where springs of clear water issue from below and fellow an irregular channel to the outlet of the old lake. Nearby are the carcasses of four elk cows and one cow moose (Alces americanus shirasi). Evidence at hand proved that the elk had stepped into this innocent looking stream-bed where they became hopelessly ensnared in the ooze and were later dragged from the mire and devoured by grizzlies.

Tossing an old bone into one of the springs, I was impressed as it slowly settled through the eighteen inches of crystal clear water to the bottom, that its downward speed was not checked as it settled from sight in this false bottom. A twelve foot stick was not sufficiently long to plumb the depths at this point.

It is interesting to speculate how many skeletons may be resting on the bottom of these death traps which must exact their annual toll from our wilderness friends who would drink there. At times the entire surface of a spring will be covered with a thick scum of hair.

In view of the present, our interpretation of conditions of the past, as revealed by certain fossil animals, becomes more fascinating and revealing.


Ranger Naturalist George Marler

The Giantess probably began erupting about three or four a.m. I first noted the activity on May 30, 1938, at 7:30 a.m. At this hour I saw several jets which seemed to rocket easily 200 feet. A number of similarly high eruptions were noted throughout the day. After making several inquiries and hearing numerous comments, I decided the eruption must have begun about 3:30 and not later than 4:00 a.m.

geyser erupting

During the course of the day the Giantess erupted periodically with intervals varying between twenty and thirty minutes. The average duration of each eruption, which was characterized by rocketing jets of water, was about five minutes. Activity was just as strong at 8:00 p.m. as during the morning hours.

At seven-thirty the following morning, there was still a churning of water in the bottom of the crater. At no time during the day was any water observed to be thrown above the rim. By 1:00 p.m. all boiling seemed to have ceased. By 6:00 p.m. water could be seen standing at a level near the bottom of the crater. At 7:30 a.m., June 1, the bowl was about two-thirds full and the periodical ebulition that characterizes the quiescent periods of the Giantess was noted. The bowl continued to fill at the rate of about eight inches an hour, beginning to overflow some time during the night of June 1. The Vault and Teakettle filled simultaneously.

At the time of the first observation of the Giantess, May 30, the water had receded two feet below the rim of the Butterfly and was boiling vigorously. This boiling continued without abatement for a period of not less than 48 hours. On the morning of June 2, the bowl was overflowing, the water being several degrees below normal in temperature.

The whitewashed appearance of the Giantess cone following the activity was only in a small measure the result of the algae having been destroyed by the boiling water. During the initial activity a large quantity of finely suspended or held silica was ejected. Whether the water had reached the saturation point for silica preceding the eruption with a resulting precipitation would be interesting to ascertain. In numerous collecting basins near the cone, this highly dissipated mineral had collected, giving the appearance of marl or a foraminiferal ooze.

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