Geoscience Reference
In-Depth Information
In Wurtemberg, the German geologist Friedrich August von
Alberti (1795-1878) was interested in the successions exposed around
the town, and spent considerable time looking for minerals of eco-
nomic value. In doing so he recognised in 1834 that they could be
subdivided into three units, the Buntsandstein (known as the Bunter
in English), the Muschelkalk and the uppermost Keuper, collectively
known as the Trias. The Muschelkalk was so named on account of its
containing a large number of fossil shells. Modifying long-established
stratigraphical nomenclature is not popular amongst geologists.
Today rocks of the Triassic are extremely well known as they are
found in the oil fields of the North Sea and in western Europe, where
the porous horizons act as reservoirs for either oil or gas, and the marls
horizons as seals on oil wells which stop the valuable commodities
seeping and escaping into overlying sediments. The Triassic in
onshore Britain is dominated by terrestrial sandstones of the New
Red Sandstone, but it also contains considerable reserves of salt and
other evaporite minerals, such as gypsum, which are extracted for use
in the building trade and in the chemical industry. Next winter as you
drive along treacherous icy motorways you will no doubt curse the
local authority for being slow to spread salt - Triassic salt - on the road
surface.
In 1830 two explorers began busily mapping vast tracts of land -
no, they were not working their way through parts of the mid-West of
America, nor walking through the virgin outback in Australia, but
were inWales, a landscape that had been highlymodified by the action
of man for at least seven millennia. These geological explorers and
great friends, Adam Sedgwick and the highly ambitious Roderick
Impey Murchison, were engaged in mapping the northern and central
parts, respectively, of the principality.
Sedgwick was a Dalesman, born and bred in the village of Dent
in Cumbria where a large monolith of beautiful Shap Granite now
stands in his memory and slows down traffic negotiating the narrow
village street. Close by this speed deterrent is the Old Rectory where
Adam was born on 22 March 1785. Murchison was a soldier, and a
