WCP2450

[1]¹

The Hermitage

Crewkerne

May 16/92

Dear Sir

I [sic] dealing with geological questions I would ask you to remember that Geology is a youthful Science & is in progress of rapid growth; that it is mainly advanced by observation & careful induction & not by the exercise of very profound thought. Hence in some respects ^questions the older "authorities" are often less trustworthy guides than the younger workers; this depends on their individual receptiveness & power of ^mental adjustment. Many mens [sic] views are permanently warped by their clinging to obsolete theories.

Now the permanence of continents & oceans fitted so well with the secular contraction theory that all who held the [2] latter seized upon the former & upon every fact by which it could be supported. There are few men like Lyell² who was always ready to reconsider every theory in the light of new facts. Hence there is at the present day much difference of opinion at the origin of the chalk. But I will venture to prophesy that in 10 or 12 years time there will be very little difference of opinion.

The secular contraction theory as a producer of mountain ranges, continents & ocean basins is dead.³ Have you read Osmond Fisher's⁴ "Physics of the Earth's Crust"⁵ which greatly helped to kill it. If you deal with mechanical difficulties in the way of the interchange of areas you must deal with Fisher; & in the first place you will have to define what you mean by oceanic & continental areas.

It seems to me you are in danger of making very arbitrary distinctions, I suppose [3] you will say the whole breadth of the Atlantic is an oceanic area, but you now⁶ claim the Caribbean as part of a continental area. Their depth has nothing to do with the question & you are simply making an arbitrary selection⁷ of certain areas because they include the modern continents; Y you will be unable to deny the a priori possibility⁸ of the Dolphin Ridge having been land at some past epoch, and will have to admit that continental land may sink till it is covered by 15000 feet of water (2500 fms).

As for the Chalk I must take your arguments as I find them, you devote some pages⁹ to trying to show that the chalk is a shallow water formation. I shall endeavour to show that this is a mistake & I shall be quite satisfied if you give me the depths of the Caribbean to form it in.

You ask what force at the bottom of an ocean could break up shells into fragments. Is not chemical force quite sufficient? fragments of certain shells & tests certainly occur in Globigerina [4] ooze. Pteropod ooze is largely made up of shell fragments, but these disappear in greater depths by solution — that is the shells formed of aragonite disappear first, those made of calcite last much longer. In chalk we only find calcite shells & the calcite parts of those shells which consisted of both materials.

I shall look forward with interest to your proposed article in Nature.¹⁰

Believe me | yours very truly | A J Jukes Browne¹¹ [signature]

D^r. A. R. Wallace F.R.S &c.

P.S. I send you by this post a copy ^of the geology ^papers12 on Barbados by Harrison¹³ & and self.

Yes this is a pretty & interesting country but as I cannot travel long distances I have to change quarters much more often than is convenient. I am now seeking for quarters in Beaminster, but shall be here for another fortnight.