ceed 
Our Rocks and theiy Fossils. 
WE have adopted an easy and slovenly way of dividing all 
rocks into primary, secondary, and tertiary, which veils from us 
the real chronological relations of evolving life in the different 
periods. The lias is ranked by geologists among the earliest 
secondary formations ; but if we were to distribute all the sedi- 
mentary rocks into ten great epochs, each representing about 
equal duration in time, the lias would really fall in the tenth and 
latest of all; so very misleading to the ordinary mind is our 
accepted geological nomenclature. Nay, even commonplace 
geologists themselves often overlook the real implications of many 
facts and figures which they have learned to quote glibly enough 
in a certain off-hand way. Let me just briefly reconstruct the 
chief features of this scarcely-recognised world’s chronology as I 
sit on this piece of fallen chalk at the foot of the mouldering cliff, 
where the stream from the meadow above brought down the 
newest landslip during the hard frosts of last December. First of 
all, there is the vast lapse of time represented by the Laurentian 
‘rocks of Canada. These Laurentian rocks, the oldest in the 
world, are at least 30,000 feet in thickness, and it must be 
allowed that it takes a reasonable number of years to accumulate 
such a mass of solid limestone or clay as that at the bottom of 
even the widest primeval ocean. In these rocks there are no 
fossils, except a single very doubtful member of the very lowest 
animal type. But there are indirect traces of life in the shape of 
limestone probably derived from shells, and of black lead probably 
derived from plants. All these early deposits have been terribly 
twisted and contorted by subsequent convulsions of the earth, and 
most of them have been melted down by volcanic action, so that 
we can tell very little about their original state. Thus the history 
of life opens for us, like most other histories, with a period of 
uncertainty. Its origin is lost in the distant vistas of time. Still, 
we know that there was such an early period ; and from the thick- 
ness of the rocks which represent it we may conjecture that it 
spread over three out of the ten great zons into which I have 
roughly divided geological time. Next comes the period known 
as the Cambrian, and to it we may similarly assign about two and 
a half zons on like grounds. ‘The Cambrian epoch begins with a 
fair sprinkling of the lower animals and plants, presumably deve- 
loped during the preceding age ; but it shows no remains of fish 
or any other vertebrates. ‘To the Silurian, Devonian, and Car- 
boniferous periods we may roughly allow an eon and a fraction 
each ; while to the whole group of secondary and tertiary strata, 
comprising almost all the best known English formations—red 
