Correspondence — Mr, James Geikie. 53o 



DISCOVERY OF BOS PRIMIGENIUS IN THE LOWER BOULDER- 

 CLAY OF SCOTLAND. 



Sir, — Mr. Eobert Craig's letter in the last number of the Magazine 

 does not require an elaborate reply. Mr. Craig seems to think that 

 the Lower Boulder-clay of Scotland is always "a tough dark blue 

 clay;" and as the deposit overlying the stratified materials, in which 

 the skull of the great ox was found, is '' mixed with sand and gravel 

 and altogether freer" than the underlying Till, it cannot, according 

 to him, be true Boulder-clay. Mr. Craig will be surprised when he 

 learns that true Boulder-clay does not always maintain the character 

 of a " dark blue," or even of a " tough" clay, — that, on the contrary, 

 it not unfrequently becomes loose and earthy, — that just such a de- 

 posit, as that which he imagines I have made a mistake about, may 

 be seen in hundreds of sections throughout the country, sometimes 

 overlying, sometimes overlain by, and in other places graduating into 

 stififer Till than itself. And he will no doubt be gratified to hear 

 that the same Boulder-clay (sometimes "tough" and sometimes 

 "free") often shows interstratified masses of clay, sand, and gravel, 

 similar in all respects to those which have yielded the remains of the 

 gl-eat ox. 



Mr. Eobert Craig remarks that both in my sketch-section and in 

 the letterpress description I have overlooked '' the fact that the 

 Lower Boulder-clay rises up through this stratified bed (i.e. the 

 deposit from which the fossil remains were obtained), throwing it 

 out altogether for more than one hundred yards in the section." 

 Now if Mr. Craig will again refer to the section I gave he will 

 observe that I have shown (Fig. 1) the ^os-beds thinning out to 

 south-west, and the underlying and overlying Till coming together. 

 If I had been describing in minute detail the geology of the district 

 I might have transcribed from my note-book the whole of the section 

 exposed : but for the purpose I had in hand that would have been a 

 work of supererogation. It was only necessary to point out that the 

 strata of clay, sand, and gravel, in which the fossil lay embedded, 

 were actually enclosed in what I believe to be deposits of Lower 

 Boulder-clay age. The former, after disappearing for a short dis- 

 tance, again come on underneath the Till ; or, as I stated in my 

 communication, 'Hhe Till further up the valley towards Shillford 

 continues to exhibit intercalated beds of clay, sand, and gravel." 

 Again, Mr. Craig misunderstands me when he says that I consider 

 the overlying and underlying deposits as identically the same. I 

 merely remarked that ''I noticed no material difference''' between them 

 — nothing that could lead me to believe theyh ad different origins. 



I have said this much because I am unwilling that any doubt 

 should rest upon the matter. The section is gradually beino- obli- 

 terated. The last time I saw it, it was decidedly in a " bad way ;" 

 and when the Bail way works are completed the resting-place of the 

 great ox will be as difficult to find as that of the Prophet. Knowing 

 that such must be its fate I made a very careful examination, and 

 from time to time revisited the spot to watch the progress of the 

 cutting, but never saw anything to throw doubt on the conclusion I 

 first arrived at. 



