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d = Sandy clay; similar to b.

e = Thin bed of marl, with a fair proportion of lime.

f = Sands and small pebbles, irregularly stratified (false-bedded).

g = Laminated sandy clay.

h = Stiff clay; can be mixed with f and passed through the pug mill.

i = Sand; an irregular bed of very local occurrence.

j = Gravel bed, with much sand.

The above is typical of deposits accumulated in river valleys; it is different in character to deposits laid down in the sea (as will presently be described); the section exhibits very different classes of brick-earth also, and yields a totally different kind of brick to that obtainable from brick-earths of marine origin. The importance of the question of origin of a brick-earth, therefore, is just beginning to dawn upon us. Many rivers are noted as having throughout a long period of time wandered from one side of the valley to the other (by the process depicted in Fig.1) several times, in which cases the brick-earth sections relating to them are liable to still greater variation. The reader would perhaps be very much astonished to find how much is known concerning peregrinations of that description in regard to particular localities, by competent authorities—usually field geologists.