IMPERFECTION OF GEOLOGICAL RECORD 253 



On the lapse of Time. — Independently of our not 

 finding fossil remains of such infinitely numerous con- 

 necting links, it may be objected, tbat time will not 

 have sufficed for so great an amount of organic change, 

 all changes having been effected very slowly through 

 natural selection. It is hardly possible for me even to 

 recall to the reader, who may not be a practical geo- 

 logist, the facts leading the mind feebly to comprehend 

 the lapse of time. He who can read Sir Charles 

 Lyell's grand work on the Principles of Geology, which 

 the future historian will recognise as having produced 

 a revolution in natural science, yet does not admit how 

 incomprehensively vast have been the past periods of 

 time, may at once close this volume. Not that it 

 suffices to study the Principles of Geology, or to read 

 special treatises by different observers on separate 

 formations, and to mark how each author attempts to 

 give an inadequate idea of the duration of each forma- 

 tion or even each stratum. A man must for years 

 examine for himself great piles of superimposed strata, 

 and watch the sea at work grinding down old rocks 

 and making fresh sediment, before he can hope to 

 comprehend anything of the lapse of time, the monu- 

 ments of which we see around us. 



It is good to wander along lines of sea-coast, when 

 formed of moderately hard rocks, and mark the process 

 of degradation. The tides in most cases reach the 

 cliffs only for a short time twice a day, and the waves 

 eat into them only when they are charged with sand or 

 pebbles ; for there is good evidence that pure water 

 can effect little or nothing in wearing away rock. At 

 last the base of the cliff is undermined, huge fragments 

 fall down, and these remaining fixed, have to be worn 

 away, atom by atom, until reduced in size they can be 

 rolled about by the waves, and then are more quickly 

 ground into pebbles, sand, or mud. But how often do 

 we see along the bases of retreating cliffs rounded 

 boulders, all thickly clothed by marine productions, 

 showing how little they are abraded and how seldom 

 they are rolled about ! Moreover, if we follow for a 



