From Daniel Mackintosh 1 December 1867
20 Sussex Street, | Winchester,
1st Dec. 1867.
Sir,
Having some idea of the extent to which your time must be occupied, I should not have troubled you with acknowledging the receipt of your very kind and considerate letter,1 were it not that for some time past I have been longing for an opportunity of consulting you on one or two points connected with Denudation.2
You may, perhaps, have noticed a number of articles by me in the Geological Magazine which have given rise to a rather warm controversy on the origin of escarpments, valleys, and plains.3 With the exception of a little assistance from Mr Hull (of the Ord. Survey) and Mr Kinnahan (Irish Survey) I have been left to fight the battle with the Subaërial school singlehanded.4 In endeavouring to answer opponents, I have been gradually led not to place too much reliance on sea-coast action, and after allowing a certain amount of influence to ice, I have been driven to oceanic currents, periodically increased in intensity by sudden upheavals or depressions of the earth’s crust, as the main excavators of valleys.5
My object in writing is to take the liberty of asking if you have published any thing, or know of any thing that has been published, on the excavating power of currents, and whether you think that their action on the chalk of the south of England (with or without ice) would be sufficient to explain the hollowing, rounding scoring, escarpmenting, and terracing, which form so striking a feature of the chalk downs.6 For upwards of a year I have been wandering among these downs with the view of generalizing all the facts connected with the terracing and scoring of their slopes. When I ventured a short time ago (too inconsiderately) to assert that there were raised beaches among the chalk downs, Mr. Poulett Scrope ridiculed the idea in the Geological Mag., and referred all the terraces to the action of the plough.7 I think I can now demonstrate that, however much the terraces may have been either enhanced or defaced by cultivation, there are thousands which are of natural origin. The most puzzling characteristic is their very frequent want of horizontality and parallelism, which at first might suggest the idea of currents rather than sea-coast action. But I have noticed a similar absence of horizontal parallelism among the smaller terraces of the North of Scotland & elsewhere. Would you kindly inform me if this be a characteristic of any of the terraces you have discovered in S. America, and whether unequal upheaval, or irregular formation during oscillations of the land, would offer an explanation.8 The finest series I have seen is near Stockbridge, on the side of the Andover and Romsey Railway.9 They are parallel, but gently inclined longitudinally. They are covered with fractured flints, mixed with thoroughly rounded pebbles.
I enclose the very rough & imperfect sketch I took on the spot.10
Hoping you will kindly excuse the liberty I take in asking for a hint or two on these subjects when you happen to have a little leisure, | I am, Sir, | Your very obliged & humble Sert., | D. Mackintosh
This will be my address for more than a week to come—afterwards Chichester
P.S. I shall gladly embrace the first opportunity of seeing the work you refer to, and shall call attention to the fact probably in the Geological Magazine.11
Footnotes
Bibliography
Challinor, John. 1978. A dictionary of geology. 5th edition. Cardiff: University of Wales Press.
Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.
Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.
Greenwood, George. 1866. Rain and rivers; or, Hutton and Playfair against Lyell and all comers. 2d edition. London: Longmans, Green, & Co.
Hull, Edward. 1867. Mr Whitaker on ‘subaerial denudation’. Geological Magazine 4: 567–9.
Kinahan, George Henry. 1867. On cliffs and escarpments. Geological magazine 4: 569–70.
Lyell, Charles. 1865. Elements of geology, or the ancient changes of the earth and its inhabitants as illustrated by geological monuments. 6th edition, revised. London: John Murray.
Mackintosh, Daniel. 1869. The scenery of England and Wales: its character and origin. London: Longmans, Green, and Co.
Oldroyd, David. 1999. Early ideas about glaciation in the English Lake District: the problem of making sense of glaciation in a glaciated region. Annals of science 56: 175–203.
Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.
Scrope, George Poulett. 1866. The terraces of the chalk downs. Geological Magazine 3: 293–6.
South America: Geological observations on South America. Being the third part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1846.
Summary
Seeks CD’s opinion and references on the causes of terraces in the south of England. He supports sea action as cause, either by currents or on coasts, and has been engaged in a controversy in the Geological Magazine [4 (1867): 571–5] with the subaerial school. Poulett Scrope thinks they are agricultural.
Letter details
- Letter no.
- DCP-LETT-5703
- From
- Daniel Mackintosh
- To
- Charles Robert Darwin
- Sent from
- Winchester
- Source of text
- DAR 171: 7
- Physical description
- ALS 5pp
Please cite as
Darwin Correspondence Project, “Letter no. 5703,” accessed on 19 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-5703.xml
Also published in The Correspondence of Charles Darwin, vol. 15