1857.] GODWIN-AUSTEN BOULDER IN CHALK. 263 



The conditions which have to be satisfied in this particular case 

 are, the removal of a large boulder, together with coast-line shingle 

 and sand, and their transference to a deep and distant sea-bed, in 

 precisely the same relative positions in which they lay together in 

 the parent beach. 



Sir C. Lyell, who had his attention drawn to the fact of the oc- 

 currence of pebbles in chalk by Mr. Catt, has adopted* the observa- 

 tions of Mr. Darwin, in preference to such other means of transport 

 as floating weed or floating ice. Sir Charles's objection to the agency 

 of floating ice is, that it is inconsistent with the conditions of climate 

 indicated by a sea abounding in chambered Cephalopods. 



At all past periods the globe must have had its climatal zones ; 

 and, taking Mollusca as our guides, we know that, for the secondary 

 and tertiary periods at least, the order or gradation was placed very 

 much as it is at present. We know, too, what is the distribution of 

 the extmct Cephalopods over the European area ; and on these joint 

 grounds it may be stated confidently that no sure conclusion as to 

 climate can be derived from the Ammonites and Belemnites of our 

 secondary formations. 



For the Oolitic period (Lower Mesozoic) the geographical distribu- 

 tion of Cephalopods is rather northern than southern, whilst for the 

 Upper Mesozoic (or Cretaceous) they decrease, both as species and 

 individuals, towards the upper chalk. 



Apart from these considerations, the fauna of a sea is no indication 

 as to whether ice from polar regions may not occasionally be floated 

 into it. All that is requisite is that the area of water should have 

 an extension into polar regions ; and then the liberated ice must at all 

 times have been distributed according to the same laws as influence 

 it now. Polar ice, it must be remembered, is now occasionally floated 

 down, and its load scattered, as low as the Azores and Canaries, 

 where its detritus becomes imbedded in deposits containing the forms 

 of the South Lusitanian fauna. 



The condition of one hemisphere of our globe at the period of the 

 greatest extension of the Cretaceous ocean, represented in the map 

 exhibited to the Meeting, shows — 1st, how, as far back as the creta- 

 ceous period, the waters of the great and old Atlantic valley extended 

 into the Polar basin ; and next, what was the extent and character of 

 the subaerial surface, the coast of which supplied the mineral mate- 

 rial for the sedimentary beds of those seas over the European area. 



I know only of two other agencies by which the coarse materials 

 of the marginal sea-zone can be conveyed away so as to be distributed 

 over the deeper sea- beds, viz. sea-plants and coast-line ice. 



Sea-plants being lighter than water, it happens that, when the sea- 

 bed of the zone of Fuci or LaminaricE is composed of loose materials, 

 such as shingle, the mass of weed attached to small blocks or pebbles 

 becomes buoyant enough to float them ; in this way, when the plants 

 have attained their full growth, and gales of wind set in, the plants 

 lift great quantities of deep shingle from off its bed, and carry it into 

 the upper sea-line. With a gale and a falling tide, the weed may, in 

 * See Manual, 5th ed. p. 243. 



