210 Greemoood — On Valley Terraces. 



buried under a ton-ent or debacle of mud and boulders, and half a 

 mile of its coiurse was damned up into a deep lake." Page 154. " I 

 met my friend on the other side of the mud torrent." Page 184, " I 

 descended obliquely down a very steep slope over upwards of a 

 thousand feet of debris, the blocks on which were so loosely poised 

 on one another that it was necessary to proceed with the utmost cir- 

 cumspection, for I was alone, and a false step would almost certainly 

 have been followed by breaking a leg. The alternate freezing and 

 thawing of rain amongst these masses must produce a constant down- 

 ward motion on the whole pile of debris (which was upwards of 2000 

 feet high) and may account for the otherwise unexplained pheno- 

 menon of continuous shoots of angular rocks reposing on very gentle 

 slopes in other places." 



So far for the present erosion of rain and rivers. For the present 

 deposit from them take Dr. Hooker's description of the Cosi (of which 

 the Yangma is a tributary) where it runs out of the Himalaya and into 

 the Ganges, page 86, vol. i., "Even at this season (April, the end of 

 the dry season) the enormous expanses of sand, the numerous shift- 

 ing islets, and the long spits of mud, indicate the proximity of some 

 very restless and resistless power. During the rains the scene must, 

 indeed, be extraordinary when the Cosi lays many miles of land 

 under water and pours so vast a quantity of detritus into the bed of 

 the Ganges, that long islets are heaped up and swept away in a few 

 hours ; and the latter river becomes all but unnavigable. Boats are 

 caught in whirlpools formed without a moment's warning, and sunk 

 ere they have spun round thrice in the eddies." 



As I have said in "Eain and Rivers," what is everlastingly ascending 

 through the air as vapour from the sea is everlastingly descending 

 through the air as rain on the land. This continuous circle of causes 

 is always washing the land into the sea. And it is fire only which 

 keeps our heads above water. Fire is the quarryman that is ever 

 raising the block, the entire land, above the sea. Eain (with atmo- 

 spheric erosion) is the chisel, which in the hand of the Almighty 

 artificer, is for ever sculpturing the block, — that is, shaping the 

 entire surface of the land, even to the topmost pinnacle of the highest 

 snowcapped mountain, for snow is frozen rain. 



Brookwood Park, Alresford, 

 ^th March, 1867. 



nsroTiCES oip nycEDvcoiias- 



I. A Beief Account of the "Thesaurus Siluricus," with a 



FEW Facts and Infekencbs. By J. J. Bigsby, M.D., F.G.S., etc. 

 [Proc. Royal Society, February 21, 1867.] 



THE "Thesaurus Siluricus" is a general view of Silurian life, as 

 far as now known, in the form of a table. After mentioning the 

 genus (taken alphabetically), its author, and the date of its establish- 

 ment, the species are successively named, and treated of under four 

 or more heads, along one and the same ruled line. First comes the 



