WCP2346

[1]

Adsett Court, Westbury on Severn

14 January 1877

My dear Mr Wallace

Many thanks for your letter & I am extremely glad you are interested in the Carbon theory & my paper no doubt would be thought a [dark] one if I were a professor — but amateurs may say what they like & I have read your remarks with great interest and place only be too glad to hear any [2] criticisms that occur to you.

I do not think there is any difficulty about the quantity of carbon deposited in the ½ ton per acre per annum, estimated as returning to the ground, is washed by 3 or 4 thousand tons of rainwater and is of course washed away from a great part of the land surface, and especially from hills, sloping ground, and the higher levels, first into brooks & hollows, then into rivers [3] and finally into the sea & it is thus collected in the various places in which permanent deposits are formed by mechanical turbulence from water, in valleys, swamps, lakes, the sides of water courses, and principally, in estuaries and along all the coast lines in the world & there coast lines measure upwards of 100,000 miles, and if we suppose the help of litteral deposits to be [4] 250 miles broad, there will be in it an area equal to half the land surface over which the washings of the land are spread & if the whole of the carbon were washed into this area it would equal a deposit of one ton per acre per annum & this would be the great carboniferous formation of that period and if the carbon were deposited at that rate without intermission, the result would be the formation of coal measures containing 20 yards average thickening of coal in 100,00 years & I don’t think [5] this would be an extravagance supposition but it is of course many times more rapid than my estimates require — only part of the carbon reaches the littoral belt ; some of it is carried thence over much wider areas; much of it remains where it first falls, in flat, hollow and forest districts, making slowly thickening beds of vegetable soil which are not generally disturbed till the time comes when they are submerged; and which are then scattered far & wide or buried under other materials; and a large portion of it doubtedly accumulates in deposits [6] of great thickness but small area, such as are sometimes formed in the coal fields & I don’t myself see any reason to think that the deposits of carbon in recent times have been less than in ancient days. There are [deposits] of tertiary coal 100 feet thick in Europe; what [we call] the Tertiary period in geologically a very short ones, and the greater part of its deposits are almost necessarily under the present seas — and recent coal being of little value is not looked for in [7] no doubt the carboniferous period was favourable to the formation of beds of coal, which are not a necessary result of the constant deposit of carbon and if the carbon of your coal measures were scattered throughout the whole thickness of the strata instead of being mixed together in seams, we should not recognise the formation as a carboniferous one in this mixing together evidently depends entirely upon the circumstances, & especially on the geographical features of the open.

As to the barren lands — I suppose there may be ten million square miles of absolute desert; through this must be a liberal allowance in Israel [8] there is an equal area of exuberant fertility, and in part the general principle would not be affected by reducing the productive area from 50 million to 40 — or even to a good deal less.

As to islands — no part of the world depends on its once local supply of carbonic acid; the whole atmosphere is so thoroughly mixed by winds that each locality is supplied by all the rest. I had indeed thought that on the food question some islands might perhaps be cited as examples of [nepehalion] coexistences with only the lower forms of [9] animal life to feed on its & on each other. But I don’t think there is any real example of this is in a small area and occassional raced an insect will keep them in check; and birds & fishes so everywhere, and island are constantly replenished with seeds from a distance, through the air or the water; & no doubt with animal life as well.

In the geological evidence, if much we borne in mind that the fresh deposits of carbon cannot occur over wide ocean beds but must [10] necessarily be in comparatively narrow & often discontinuous lines & that our knowledge of their extent in any geological epoch, depends therefore mainly on the position of the chief lines of upheaval in whole continents may give to the surface without bringing any of the chief carbon deposits of their period as it happens that the coal bearing portion of the rocks of the carboniferous age has been very extensively brought to the surface; but this could not be expected to be the case in the [11] next great period; now indexed often in the world’s history.

Your suggestion about the exhaled nitrogen is very interesting, I should much like to know what Dr Gilbert thinks — It seems almost necessary, tho; it has not been discovered, that there should be some organic process by which uncombined nitrogen is either taken as food by plants or animals, or else made to enter into combinations which can be assimilated as manures seem often to stimulated rather than to nourish [12] the chemists are in the dark on this point. A field of clover attracts vast & various of grown up insects from other places & if possible that they can die there in sufficent numbers to add sensibly to the nitrogenous elements of the soil? — there is always the ammonia present in the air, which some place be may appropriate largely, to others but, by the help of rain if not there as the leaves.

I have sent a copy of my paper [13] to Darwin at your suggestion.

Believe in me | Yours truely | Hubert J. Mott

I wish I could see once of the often finalised phenomena with my own eyes & [Nub] hour is it to be done?