Travel Reference
In-Depth Information
cross beds, the presence or absence of conglomerates, and any trends dis-
cernible in these features. No high technology was needed—just detailed ob-
servation carefully recorded in field notebooks.
After several days of this our results were clear. There was no evidence
of a sudden drop in sea level coincident with the great mass extinction. In
fact, we found just the opposite. The water in this region (and in many oth-
ers, it turned out) was deepening when the extinction occurred, not shallow-
ing. Sea level was not the culprit. Abundant evidence eventually showed
that eatth's collision with a gteat comet in the Yucatan region of Mexico was
the real killer.
At the end of a week the various geologists left for their home coun-
tries. I stayed on to spend more time in the field, for my work here was still
unfinished. The hills in this part of Tunisia contain thick successions of sed-
imentary tock exactly the same age as the sedimentary rocks in the Vancou-
ver Island region. Here was an ideal test of the hypothesis that sea level
change is nearly always caused by global events rather than due solely to
local events such as regional uplift, which might be caused by mountain
building. Here I could see whether the pattern of sea level change so won-
derfully exposed on the various islands of the Vancouver Island region was
caused by global rather than regional processes.
El Kef is located in the central part of Tunisia and is at sufficient alti-
tude that spring comes late. It seemed ironic to be so cold here, for to the
south of us lay broad desert regions, giving way to the patched and hot Sa-
hara. It was a small town, with few of the Western trappings that character-
ize the larger cities fatthet north in Tunisia. A truck with a loudspeaket
drove through the town each morning and evening, calling the faithful to
the mosque. Arab men thronged the bars and cafes, but few women were to
be seen. I could feel the discipline of the place, and its strangeness to me was
palpable.
The days in the field were long and exhilarating. The rocks were laid
out as if by giant brushstrokes across the face of the low mountains, alterna-
tions of thick limestone and dark shale stteaked across the rugged country-
side. Ammonites had been reported from here but had barely been studied. I
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