Geoscience Reference
In-Depth Information
operating seismographic stations in the continental United States were
those maintained by Johns Hopkins in Maryland, the Lick Observatory in
California, and the Weather Bureau in Washington.
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Meanwhile, a truly remarkable seismic event escaped scientific notice
entirely. in 1905 Ralph Tarr and his young colleague Lawrence Martin ar-
rived in Alaska to conduct a general geographical survey of Yakutat Bay. The
bay lay beneath steep white mountains, on the border between Canada and
Alaska, where glaciers stretched from some of the highest peaks down nearly
twenty thousand feet to the sea.
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“Before going to Alaska in 1905 we had
seen one account of an earthquake in Yakutat Bay, in 1899, but many of the
alleged facts were grotesque and failed even to encourage us to expect earth-
quake phenomena in the region. it was a thorough surprise to us, therefore,
when, early in our work, we came upon clear evidence of recent uplift, in
barnacles attached to ledges high above the reach of the present tide and
among land shrubs.” Suddenly, Tarr and Martin began to look at the beach
from a new perspective. Those blue flowers they had earlier seen on rocks
high above the water? Only now did they see that these were mussel shells.
now they could make sense of the extensive “benches” that provided them
with convenient rocky surfaces for walking beyond the reach of the tides.
They continued to collect evidence of recent uplift “until practically every
foot of a shore line 150 miles in length had been examined.” Several years
of subsequent field studies showed how profoundly the earthquake had
transformed the face of the land, even prompting the recession of nearby
glaciers in the absence of climatic change.
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it was an investigation driven
by the enduring question of the American West, the question of the physical
determinants of wilderness versus civilization.
However dramatic the physical evidence, it was their conversations with
native canoemen that convinced Tarr and Martin that the 1899 earthquake
was responsible for a dramatic transformation of this landscape. Their in-
vestigation is a story of scientific forensics and of a slow but sure appre-
ciation of the value of eyewitness testimony. The scientific expeditions to
the region in 1895 and early 1899 provided only “strong presumptive evi-
dence” that the changes were of a more recent date. But the natives “state[d]
definitely that the uplifts took place in connection with the earthquakes of
the fall of 1899 and that there were no similar recent movements before or
since.” “natives,” wrote Martin in a preliminary report, “notoriously tell
you whatever you want them to, especially if they can not speak your lan-
guage well.”
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There were, however, “several reasons for considering [the
natives' testimony] trustworthy. Our questions put to the natives were never
in a form to suggest the answer desired. One of our canoemen in 1905,
