Geoscience Reference
In-Depth Information
the southern end of Cardigan Bay in westernWales. In the Elgin region
of Scotland, various sandstone units crop out, and the age of these
particular units caused some difficulties to workers in the field in the
1850s. Roderick Impey Murchison visited them in the company of a
local cleric, the Reverend George Gordon (1801-1893), and declared
them to be Old Red Sandstone. This pronouncement was thrown in
doubt by the subsequent discovery of reptilian footprints, which sug-
gested a younger New Red Sandstone affinity. Gordon, with another
cleric, the Reverend Dr James Maxwell Joass (1829-1914) covered the
ground again and confirmed to Murchison that the units could not be
separated by breaks in the succession, and they declared the Elgin
Sandstones to be Old Red Sandstone. Murchison held to this for
some time, but eventually in the fourth edition of his masterful
book Siluria, published in 1861, recognised that at least some of the
units were New Red Sandstone.
St David's is a beautiful part of Wales that is closely associated
with that country's patron saint. If one examines a contemporary
geological map of the area, it shows that Precambrian rocks are over-
lain by Cambrian sediments. In 1882 Archibald Geikie, another
powerful geologist, who was appointed that year as Director General
of the Geological Survey of Great Britain, wrote a long paper on
the geology of St David's, which pitted him against the lesser influ-
ence of Dr Henry Hicks (1837-1899), a local medical doctor. Hicks was
a geologist of some considerable ability in his own right and later
served as President of both the Geological Society of London and the
Geologists' Association. For some considerable number of years prior
to Geikie's interest in St David's, Hicks had carried out investigations
of the local geology and had published papers on it in some important
geological journals. What aggravated Geikie was that Hicks had
described a portion of the St David's succession as being of
Precambrian age: in his examination of the geology, Geikie could
not agree and placed the succession firmly in the younger Cambrian
Period. He presented his paper in two portions to the Geological
Society in London at two meetings, on 21 March 1883 and then on
