Geography Reference
In-Depth Information
59
Nevertheless, this discovery was tantalizing, and gave hope that somewhere in the upper
drainage of Ferrar Glacier a fossil would be found.
In 1902 fossils were still the only way to date a rock and place it on the geological
timescale (Appendix 2). Bertram Boltwood would not perform the first radiometric date
by isotopic analysis for several more years. So for Ferrar, a fossil was the grail that would
allow him to relate his sequence of sandstones to those rocks elsewhere around the world
that had formed at the same time in Earth history.
From the campsite on the north side of Finger Mountain the party pulled over to the
north side of Ferrar Glacier and camped at the foot of the Inland Portals at the same site
where the outward party had camped on November 2. For four days Ferrar crawled all
over the bare-rock ridges of the Inland Forts, including an eight hundred-foot climb up
one of the steep cirques, but he found no fossils and no more carbonaceous rock. On No-
vember 18 the party crossed back to the moraine downstream from Finger Mountain and
from there hiked deep into Beacon Valley, the ice-free canyon for which Ferrar named the
sedimentary sequence Beacon Sandstone (Fig. 2.13). Still no fossils. On November 21 the
men moved down to a camp on the moraine at Knobhead, having picked up supplies at
the New Mountain depot. For the next several days Ferrar worked around the south side
of Knobhead, climbed eight hundred feet up its eastern face, and hiked across the glacier
to Solitary Rocks. On the morning of November 24, he hiked over to the northern tip
Figure 2.13. Horizontal lay-
ers of Beacon Sandstone
constitute the walls of Bea-
con Valley, first explored by
Ferrar in January 1903. This
was the first place where
the horizontal sedimentary
rocks of the Transantarctic
Mountains were named.
With the recognition by
later geologists that these
sedimentary rocks occur
throughout the length of
the Transantarctic Moun-
tains, the name Beacon
Supergroup was applied to
the entire suite.
