76 



.1. W. SPENCEK — ANCIKNT SHORE PHENOMENA. 



of the coastal plain back of a cut terrace (c, fig. 4) and the bounding hills, as 

 the exact water-level can here be only approximately determined. It is 

 more accurate to make the calculations as to the former water-levels from 



the top of the ridges than from the foot of the beaches, as the slope in front 



FlGUttE C>.— Plan of Bnrrier Beach in front of a I by Hills. 



6=Line of Hills, s— -Barrier Beach. The beach ends abruptly on the left. 



of tlu'in i- steep in one place, and in another very gentle, but the summit is 

 easily recognized. Where the beach itself is absent, by tracing the coastal 

 line, there will be found sooner or later, a bar or spit in front of some 

 river or extinct bay. 



In ascending from the modern lakes to the highlands, several old shores 

 must be crossed. The country may be described as a series of terraces or 

 steps, whose frontal margins are moulded into hills, and whose surfaces are 

 plains, most commonly ol clay, although Bometimes of gravel or sand, at 

 the back of which, there may be found the beach in some form. These 

 gi ntly rising terrace plains may each be several miles in width — and con- 

 sequently the beaches several miles apart — or they may be narrow with the 

 beaches close together. In many regions, the old shores behind these plains 



rise and extend across the country as < spicuous ranges of hills. The 



plain.- themselves are occasionally eroded by b1 reams, until the whole country 

 is very broken. This is more likely to be the ease with terraces of the 



greater altitudes, and here the more recent sui face erosion has often rendered 

 the ancient shore lines hard to follow. 



In crossing a Beries of beaches, the lowest is found to be composed of the 

 Bnesl gravel, or indeed perhaps of sand. In this case it is apt to be more 



or less leaped into dunes, by the action of winds. The ridges are often 



divided, but the branch* a unite again, or else Bend out spits ending abruptly. 

 iasionally the materials from which the beaches were formed \\a< Btony 



-and, in plat f -tony clay. Here, then, the extinct water-margins are 



difficult to determine, for there is no -harp lithological character, as where a 

 beach a clay plain to mark the boundary between the Band beach — 



commonly heaped into hummock- or dunes- and the frontal plain composed 

 of Band. 



