568 Notices of Memoirs — J. Lomas — On Moraines, etc. 



Walton, but contains some boreal and Arctic species unknown from 

 that place, including Neptunea antiqua (dextral), N. carinata, and 

 N. despecta, and represents the period when northern forms were 

 first beginning to establish themselves in the Crag basin. It is 

 approximately and partly equivalent to the Poederlien zone of 

 Belgian geologists. 



The Eed Crag beds, the fossils of which are, with few exceptions, 

 the drifted and stratified shells of dead mollusca, seem to have been 

 deposited either against the shore or in shallow water in proximity 

 to it, in land-locked bays or inlets. The position which these 

 inlets successively occupied was from time to time shifted towards 

 the north, in consequence of the upheaval of the southern part of 

 the Crag area described by the author in a former paper.^ These 

 inlets were silted up, one after another, by masses of shelly sand, 

 but as far as the evidence goes the beds composing the different 

 zones do not overlap. The Waltonian deposits are confined to the 

 county of Essex, the Newbournian occupying the district to the 

 north of the river Stour, and the Butleyan beds occurring along 

 a narrow belt extending northwards from Bawdsey at the mouth 

 of the river Deben. The Icenian deposits which are found to the 

 north of Aldeburgh are shown by their molluscan fauna to belong 

 to a period considerably more recent than any part of the Eed Crag. 

 They cover an area 45 miles by 20 in extreme breadth, and in one 

 place are nearly 150 feet in thickness, but they are not anywhere 

 Icuown to be underlain by beds of Red Crag age. In the noithern 

 part of the Icenian area Astarte borealis occxirs, and this species 

 seems to mai'k a slightly more recent horizon of this zone. The 

 Weybournian Crag, containing Tellina balthica, is only known to 

 the north of Norwich, and extends from thence to the Cromer coast. 

 The author now believes that these latter beds are distinct from and 

 of older date than the Westleton Shingle of Prestwich. 



II. — On the Origin of Lateral Moraines and Eock Trains.^ 

 By J. Lomas, A.E.C.S., F.G.S. 



IN dealing with the accumulations of fragmentary materials 

 associated with glaciers it is necessary to distinguish between 

 deposits which are stationary and the debris riding on or moving 

 with the ice. 



The latter, reviving a term used by Eendu, will be referred to 

 as ' rock trains,' and the meaning of ' moraines ' will be restricted 

 to stationary deposits, either lateral or terminal. 



Lateral moraines are not necessary adjuncts to glaciers. Their 

 distribution, which appears capricious, reallj' conforms to a well- 

 defined law. In glaciers with a straight course, they are feebly, 

 if at all, developed, whereas those moving through winding channels 

 have lateral moraines developed in their concave bends. The debris 

 carried by a glacier either in the ice or on the surface gradually 



^ Quart. Journ. Geol. Soc, vol. lii (1896), pp. 773. 



^ Abstract of a paper read before Section C (Geology), British Association, Dover 

 Meeting, Septenaber, 1899. , 



