Manchester Literary and Philosophical Society, 141 



the last volume published by the Palseontographical Society. He 

 had found casts of the pith of the Sigillaria vascularis which or- 

 dinary collectors would call a Calamite, and in two specimens of 

 Dadoxylon he has met with Calamites connceformis as the pith of one, 

 and C. approximatus as the pith of the other. Sternbergia has long 

 been known to be the pith of Dadoxylon, so now the genus Calamites 

 in all probability will have to be very considerably modified and 

 some of its species classed with other genera. 



" The Hematite Iron Ore Deposits of Whitehaven : Notes on the 

 Aldby Limestone, Cleator Moor," by W. Brockbank, F.G-.S. 



The mountain limestone of the Cleator district forms an escarp- 

 ment to the valley of the river Eden, from Egremont round the 

 base of Dent Fell, towards Cockermouth. It rests upon the old 

 clay-slate of Skiddaw and Dent, and is the outcrop of the White- 

 haven coal field. It contains most extensive and valuable deposits of 

 hematite iron ore. The easterly side of this large limestone surface 

 is deeply fissured in every direction, and when the crevices are not 

 filled with till, they are found to contain hematite ore. The escarp- 

 ment sloping towards the river Eden is made up of breccia of 

 hematite ore and limestone, in large irregular blocks, cemented 

 together into a compact mass. It is so rich with ore at the surface, 

 as to be worth working, and an open quarry was commenced, and a 

 large quantity removed, but the impurity of the product soon led to 

 its abandonment. It is very evident that this face of limestone was 

 at one period covered with a large deposit of hematite ore, since 

 denuded. 



ooE/iazESi^oisriDEinisroiE, 



ON DENUDATION, AND THE CEAGS. 



Sib, — Colonel Greenwood's letter can hardly be considered a reply 

 to my views, because he does not meet my difficulties. Arrayed in 

 seven-leagued boots, he plants one foot in Norfolk, and the other 

 in the valley of the Amazon, and in two sentences fights the battle 

 of denudation over half the globe. But controversy is not my object. 

 I see many appearances which favour the rain theory, and admit 

 that it can explain many facts, and I believe that what Colonel 

 Greenwood says about the migrations of soil is, under present cir- 

 cumstances, quite correct. But although pluvial denudation is now 

 going on here, it is not so everywhere-— not so, for instance, in 

 Greenland, nor on the Antarctic continent. Are we sure that what 

 is now the case in Greenland was not the case in this and in many 

 other coimtries, when the present surface was shaped ? I see indi- 

 cations which lead me to suspect such to have been the case. What 

 interpretation does Colonel Greenwood put upon them ? 



If, instead of reasserting his opinions, which are already suffi- 

 ciently strongly stated in his very amusing book, he will come down 

 to details, and meet the difficulties which I have pointed out, he 

 may, if he thinks it worth while, convert me and perhaps some 

 others. Particularly I would ask him to explain how the basins 



