12 Rev. Edwin Hill — Lifting by Ice-melting. 



more prevalent : Reracleum sphoyidyUum, Lotus coniiculatus, Potenttlla 

 anserina, Tussilago Farfara, Itatmnculus hulbosus, R. repem, R.ficaria, 

 Cardaniine flexuosa. Lychnis dioica, Arenaria trmervis, Oxalis aceto- 

 sella, Vicia cracca, Circcea lutetiana, Sanicula europma, Bipsacus 

 sylvestris, Nepeta glecJioma, Rumex viridis, Arum maculatum, L)es- 

 champsia ccespitosa, Broiimn asper, etc. 



The sandy beds are well distinguished by the occurrence of such 

 plants as Rumex acetosella, Aira prcecox, Eypochcsris radicata, Crepis 

 virens, Linum catharticum, Cerastmm triviale, Festuca ovina, Agropyron 

 repens, Rubus rtisiicatius, Plmitago media. 



The plants of alluvial ground are also very characteristic, con- 

 sisting largely of marsh or wet meadow plants, chiefly of northern 

 origin. The following are useful in the recognition of alluvium : 

 Spircea ulmaria, Veronica heccabmiga, Caltha palustris, Cardamine 

 pratensis, Phalaris arwidinacea, Poa trivialis, Apium nodiflorum, 

 Juncus glaucus, J. effusus, Carex glauca, C. riparia, C. paludosa, etc., 

 Alopeciirus geniculatus, Geranium robertianum, etc., Mentha hirsuta. 



IV. — On Lifting bt Ice-melting. 



By the Eev. Edwin Hill, M.A., F.G.S., 

 late Fellow of St. John's College, Cambridge. 



EYEEYOISTE knows that ice floats in water, is able to carry some 

 amount of materials attached to it, and if lifted by rise of the 

 water-level is able to lift them with itself. Lyell describes this in 

 the Principles (ch. xvi, xxxi), and probably it is mentioned in every 

 textbook. Eut ice is also able to lift attached materials without 

 rise of the water-level. It requires no tides, no floods ; it can lift 

 without external aid, by its melting alone. 



When a crust of ice 1 foot thick lias formed on a sheet of fresh 

 water it floats with its upper surface about an inch above water-level, 

 its lower surface about 11 inches below.' If by any cause this 

 ice-crust is melted over its upper surface, the products of melting 

 flow off, the upper surface sinks a little, but the lower surface rises 

 through about eleven-twelfths- of the thickness melted off. Take 

 an ice-floe uniformly 6 feet thick : its lower surface will be floating, 

 if the water be fresh, at about 5^ feet below water-level. Suppose 

 it reduced by melting over the upper surface till only 6 inches thick, 

 the lower surface will now be about 5^ inches below water-level ; 

 this lower surface will accordingly have risen more than 5 feet. If 

 any objects or materials were attached to that lower surface they 

 Avill have risen with it: they will liave been lifted. This is un- 

 deniable and obvious. It is undeniable and obvious that ice is able 

 to lift materials by simple melting, independently of any other power 

 or action. 



An ice-crust may be conceived as melted only over the upper 

 surface. It seems not unlikely that most of the melting takes place 



^ With ice of sp. gr. -918, -984 inch above, 11-016 inches below. Captain 

 Scott thought that the ice of Antarctic bergs may be much lighter (Voyage of 

 Discovery, vol. ii, p. 411). 



=> 11-016 out of 12. 



