Geoscience Reference
In-Depth Information
one side, while the mountains crashed down on the other. it may have been
the most extreme display of sheer tectonic power ever seen by human eyes.
“About 20 yards back of the beach and above us about 100 yards was a lake
about 2 acres in area and 15 to 30 feet deep. This lake broke from its bed
and dashed down upon our camp while we ran along the shore and escaped
its fury. everything went before it or was buried by the thousands of tons
of rock that came down. This deluge was almost immediately followed by
one from the sea. A wall of water 20 feet high came in upon the flood from
the lake and carried all debris back over the undulating morainic hills.”
it seemed to the men that the glacier itself “ran out into the bay for half a
mile,” though Tarr and Martin judged more likely that a mass of icebergs
had been thrown into the sea. What the prospectors knew for sure was that
the ground was “cutting some of the queerest capers imaginable.”
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While
three of the men made it safely to higher ground, the others were caught
running back and forth between the furious waves. eventually, the earth
settled down. To get some rest, the men tied themselves by their clothes to
the trees on the mountain side, to avoid “being carried away.” Had they not
been able to recover one of their boats and rescue a lost canoe, they would
have been trapped for good. As they forded their way through the icebergs
and toward the village of Yakutat, they saw marks left by the tidal wave
“fully 60 feet up the bluffs.”
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Tarr and Martin judged that the prospectors' story “contributes little of
scientific interest.”
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nonetheless, in their final report, they told this tale as
the “thrilling story” that it was, devoting three pages to it and mostly let-
ting the men speak for themselves. The authors did not turn their attention
away from the prospectors until the men had made it safely to the village
four days after the main shock. By contrast, the authors devoted a mere
paragraph of their final report to seismographic records. As Grove Karl Gil-
bert pointed out in his preface to the final report, few “great shocks” since
the advent of seismography had been “adequately” and “directly observed.”
in other words, teleseismic analysis as yet had little value in the absence of
field studies. Gilbert attempted to differentiate between “two directions” in
the study of earthquakes: “in its relation to man an earthquake is a cause.
in its relation to the earth it is chiefly an incidental effect of an incidental
effect.”
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Yet Tarr and Martin's analysis frustrated this distinction at every
turn. They showed how an analysis of the earthquake as a geophysical “ef-
fect” was inextricable from an appreciation of the event “in its relation
to man.”
Roughly eight years after the earthquake tore through the region, Tarr
and Martin sent a questionnaire to about six hundred addresses in Alaska,
