Leonard Horner and the Geology of Bonn

Horner, L.  1836.  On the geology of the environs of Bonn.  Transactions of the Geological Society of London 4(2nd series), 433-481.

This paper was presented in 1833, but not published until 1836.  Horner lived at Bonn from 1831 to 1833 and during that time he produced a pioneering map of the region, and made some interesting observations of loess. An outline version of his map was published in volume 3 of the Principles of Geology by Charles Lyell..

Schwarz, Christoph.  2014.  Die Geschichte der geologischen Erforschung des Siebengebirges.
Createspace Independent Publishing Platform (2nd.ed) 190p. [ISBN 13: 978 1494 3817 90]

Horner fertigte die erste Karte des Siebengebirges an- in einer recht ungewohnlichen Ostausrichtung; seine topographische Karte is nicht von Muffling, sondern englischen Ursprungs; auch enthalt sie keine Hohenlinien.

Horner veroffentlichte 1836 :'Geology of the Environs of Bonn'. Er war der erste, der erkannte, dass bis dato Trachytkonglomerat angesprochene Gestein in Wahrheit Trachytuff ist. Er estellte die erste topographische Karte des Siebengebirges.

This is the one figure in Horner 1836. An early representation of loess (one of the first). H wrote:
'The ground is so covered with vegetation that it is very rarely that the different rocks can be seen in contact. In one place only have I been able to discover the trachyte and grauwacke together: this is behind the village of Rhondorf, at the Bruckersberg, where trachyte rises under grauwacke strata, inclined at a high angle, bent and broken, and both are covered by a thick unstratified mass of loess. The trachyte is much decomposed, but at a short distance is tolerably fresh.'

*** we need pictures of Leonard Horner; there is a real shortage of pictorial representation; the 1846 BAAS sketch has just come to light; there might be other hidden likenesses- please find and report..

 

Leonard Horner & some dust

Leonard Horner touched briefly on the topic of airborne dust during his presidential address to the Geological Society of London in 1847:

'You may probably recollect having read, in the newspapers of the autumn of 1845, an account of a quantity of dust having fallen from the atmosphere on the Orkney Islands; it was also said to have fallen to the thickness of an inch on ships in that part of the North Sea. It was supposed to indicate a volcanic eruption of ashes in Iceland; and the conjecture was proved to be correct; for, on the 2nd of September of that year, the great volcanic mountain of Hecla, after a repose of nearly 80 years , again burst forth. On the same day, a quantity of dust fell on a Danish ship in lat.61N., and longitude 7 58W. of Greenwich. It blew at the time strong from the NW by W. From this point Hecla is 533 miles distant...

In the Proceedings of the Royal Academy of Berlin for December 1845, there is an account of a paper read by Professor Ehrenberg, containing the result of a microscopic examination of the dust that fell on the Danish vessel; and in the Proceedings for May last there is a supplement to that paper, describing his examination of some ashes that had been erupted from Hecla on the day above-mentioned. Translations of these notices are given in the last number of the Quarterly Journal of this Society. In these notices, Professor Ehrenberg identifies the dust that fell on the ship with the ashes erupted from Hecla, and they afford another instance of that very remarkable fact, previously made known to us by the same philosopher, viz. the presence of the siliceous shells of infusoria in ashes ejected from volcanos in many different countries. He found thirty-seven different species of these minute organisms, not one of them decidedly new, and all of them peculiar to fresh water. Fifteen of them are living forms known to exist at present in Iceland.'

 

Leonard Horner & Egypt

Horner, L.  1855.  An account of some recent researches near Cairo, undertaken with a view to throwing light upon the geological history of the alluvial land of Egypt. Philosophical Transactions of the Royal Society of London 145, 105-138.
read 8 February & 15 February 1855
Proc.RSL 7, 1854-1855, 233-240 (the report of the presentation).

Horner writes on the silty ground of Egypt. This could be one of the first papers of scientific historical geology; Horner certainly emphasized the importance of time for the geologist. He must have been the first person to appreciate, and to write about silt. His early work was on loess silt, he studied the silt suspended in the river Rhine, and he moved on to Nile silt. The Nile could have been a loess river but the silt never reached the aeolian transportation stage.

Also of interest:
Lepsius, Richard  1853.  Letters from Egypt, Ethiopia & the peninsula of Sinai. (translated from the German by Joanna & Leonora Horner; with an appendix by Leonard Horner). H.G.Bohm London 578p [OCLC 3626811]

Horner added a section about the interaction of the Nile with its bed- and chronological implications. The original Lepsius volume was translated by Joanna & Leonora Horner, daughters of LH.

Leonard Horner in 1846; a sketch, for the Illustrated London News, made at the Southampton 1846 meeting of the British Association for the advancement of Science. LH was president of Section C Geology.

LH writes to Mrs Horner:  Manchester 28 March 1852
'You ask me to give you a more clear idea than you have of the object of my researches in Egypt, and I will try to do so. According to records that go back to a very remote period, the Nile has every year overflowed its banks at a particular season, to such an extent as to cover with water the low land on each side of it, and that large portion at its embouchure, which, from its resemblance to the form of the Greek letter D, is called the Delta, that being the name of that letter. The water during the inundation is very muddy, and as the river has a very slight fall, the mud is deposited on the land over which the water spreads. As the amount of the inundation is on an average of years' uniform, so also is the amount of mud deposited uniform, and it has been calculated, by some very exact observations of the French, at the end of the last century, that every hundred years the mud deposited amounts to five inches. This amount, however, is subject to certain irregularities according to the localities.

If, therefore, perpendicular boring through the mud-deposit be made, for every five inches of that passed through, we may reckon (according to the assumed rate of increase) one hundred years, and thus if five hundred inches were gone through, it would indicate ten thousand years since the lowest of the five hundred was deposited.'