Address to the Royal Geographical Society of London : delivered at the anniversary meeting on the 24th May, 1852 : preceded by observations on presenting the royal medals of the year / by Sir R.I. Murchison.

  • Murchison, Roderick Impey, 1792-1871.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Address to the Royal Geographical Society of London : delivered at the anniversary meeting on the 24th May, 1852 : preceded by observations on presenting the royal medals of the year / by Sir R.I. Murchison. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    atlas of Bavaria, in 15 sheets, is also in preparation, as well as a large Geological Map of the Bavarian Tyrol, by M. Schaffhautl. As I happen to know that the admirable sheets of our own Geolo- gical Survey of Great Britain and Ireland, conducted by Sir Henry T. De la Beche (the result of the united labour of many hands and heads), have been presented to the Bavarian Government, may we not hope that the works of all the geologists who have examined the Bava- rian Tyrol and the adjacent tracts, shall, like those of our own survey, be digested into a true principle of classification, before geological colours be applied to the very varied rocks of that complicated and metamorphosed region? In truth, a map cannot be called geological which, like a general one of M. Schaffhautl (of which we have re- ceived a sample), represents masses, known to be of the same geolo- gical age, under different colours, expressive chiefly of their litho- logical variations. A map so coloured may be curious, and even valuable, as a petrographical index, and as the result of minute labour; but is foreign to that methodical arrangement on which geological order can alone be founded. Switzerland.—In speaking of the progress which has been made in the topographical survey of Switzerland, I would specially direct your attention to four sheets of the cantons of Appenzell and St. Gallen, which M. Ziegler, of Winterthur, who has drawn and executed them, has just presented to us. They form part of a survey on the same large scale of 2h inches to a mile, or which is also in the course of application to the cantons of Zurich and Schaffhausen. To give full effect to these four sheets only, M. Ziegler passed six con- secutive summers in the mountains and valleys of St. Gallen and Appenzell, the geometrical measurements of which had been made under the direction of M. Eschmann. The inspection of the results will, I am sure, lead any of you who have studied map-making to agree with me, that they are samples of a fidelity to nature which has rarely been attained. M. Ziegler soon found (M. Leopold von Buch and M. Escher von der Linth being his counsellors) that every class of rock has a peculiar “ facies,” and hence he became convinced, that no really good topography can be made by surveyors who neglect geological data. Thus, in these sheets the eye of a geo- logist at once seizes the rugged escarpments of slaty rocks, the undu- lations of limestone, or the bosses of conglomerate or nagelflue ; whilst, from personal inspection of a portion of the difficult region here repre- sented, I can truly say, that I never yet saw a map more completely ready to receive the colours of a field geologist. The lights are
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