450 
marked by irregularities iu the deposits, or by the action of 
torrents that formed the closing scenes in this county of the 
“ Great Ice Age.” 
Ecgarded from a physical, but certainly not from a poetical 
point of view, “a river,” says J\Ir. Mellard Eeade, “is a main 
drain for part of an island, or a continent. A channel that has 
been made by the ceaseless rushing of water for untold ages, a 
silent higliway by which water taken up by evaporation in tho 
atmosphere from the great oceans, condensed in the form of rain, 
returns again to the sea in a collected form, along a line of least 
resistance.” 
Such thoughts lead us to the commencement of our rivers, over 
a tract made up of gravel and sand, of clay or marl ; and this 
looking back to the beginning may assist us iu understanding how 
it is that our higher elevations are more usually composed of sandy 
and gravelly deposits, in other words, of porous strata; the low 
lands of clay or marl, or of impervious strata. This we shall find 
a well-marked rule throughout the central parts of England — 
where sandstones, and more or less porous limestones, alternate 
with clays. 
On the clayey strata the I’ainfall must accumulate or fiow away 
at once towards lower levels ; on the sandy and gravelly strata 
it will sink down until arrested by impervious beds beneath. 
Hence the earliest exposed channels no doubt commenced on the 
clayey areas that formed the surface. And we know for a fact 
that the action of running water is to erode, to deepen its channel 
in the higher course of the stream, and wear away the banks, 
carrying the material to the lower grounds or out to sea. The 
action of rainAvater is also in part chemical, as before mentioned, 
being potent in Avearing aAvay calcareous strata, such as our 
Chalk or Chalky Eoulder Clay, Avhose upper surface is generally 
furroAved in irregular pipes. This material is carried aAvay by the 
streams. Beneath the gravelly and sandy tracts, the rainfall formed 
subterranean courses, fioAving, in some instances, even out to sea 
in that Avay, as Ave noAV Avitness in the case of numerous springs 
issuing from our cliffs on tho coast. There deep channels or 
“ chines ” are in time formed, and the gravelly accumulations 
* Trans. Liverpool Gcol. Assoc. 1882 . 
