354 



THE ORIGIN OF THE CLEVELAND IRONSTONE.* 



\)r. U. CLITTOX SORUV, F.R.S., F.G.S., etc. 



I\ July 1856, I made a short communication to the Geolog'ical 

 and Polytechnic Society of the West Ridini^^ of Yorkshire on 

 this subject, which was printed in the Proceedings of that 

 Society at the time. As, however, the publication in which it 

 appeared has been loni^ out of print, and is now rarely met 

 with, and as the opinions therein expressed have not in any 

 way been modified, it may be an advantag^e to repeat what was 

 then stated, at the same time adding a note giving results of 

 subsequent observations. 



The investigfation of the circumstances that have g'iven rise 

 to the various rocks that are met with, constitutes a branch of 

 Geolog"y of considerable interest. It has too frequently been 

 supposed that stratified rocks were accumulated in a form far 

 more like what they are now, than is warranted by a more 

 careful enquiry ; and this has, in many cases, led to the con- 

 clusion that the conditions under which they were found, were 

 unlike those occurring at the present period ; whereas they 

 may, perhaps, have been exactly the same, and the difference in 

 the aspect of the rocks brought about by a subsequent change 

 of the same nature as must also now take place in many 

 localities. The case before us is an example of this. The 

 Cleveland Hill ironstone, now so extensively worked at Eston, 

 near Middlesborough, is composed, to a very great extent, of 

 carbonate of iron, and yet it can scarcely be supposed that such 

 a deposit could be formed in any modern sea ; because, owing 

 to the strong affinity of the protoxide for oxygen, it would be 

 accumulated as the peroxide. Besides this, I am not aware 

 that there is any sea in which any great amount, even of this, 

 is now deposited, except with a very considerable quantity of 

 other substances mixed with it ; its chief source being the 

 decomposition of such silicates as the augite and hornblende of 

 various traps and hornblendic schists, which, in some cases, 

 would yield a clay containing one-third of its weight of this 

 oxide. 



If the stone be carefully examined, it may be seen that it 

 contains more or less entire portions of shells. In some cases 

 these are still of their original composition, and consist of 



• Re.'itl at the Giii.sboioiiyfh Mi.etinif of the Yorkshire Naturalists" L'nioii. 



Naturalist, 



