166 GEOLOGY. 
The Lias is the oldest, and receives its name, a corruption of lers or 
layers, from the thin variegated beds of which the rocks are composed, 
and which present a remarkable ribbon-like appearance not easily for- 
gotten. The Oolite! is above the Lias, and is so called from the rock 
hemes greatly composed of small round pS. like the eggs of the cod, 
so that it signifies the egg-rock, being called also roestone and peastone, 
according to the size of the particles. These strange granules consist 
almost entirely of lime or grains of sand coated with liste! The Wealden 
is the highest rock in the series, and receives its name from being 
developed largely in the /Veald in Kent and Sussex. The name Oolitic 
has been applied to the whole system, because the egg-structure is 
common to all the rocks in the series, although the term Jwrassic, from 
its being largely found in Mount Jura, is given to it by some geologists. 
The Oolitic system consists of a series of sandstones, limestones, some- 
times so hard as to be used as marble, shales, and clays, while ironstone 
bands, coal, lignite, and jet are abundant. ‘The sandstones are useful as — 
building-stone, the celebrated Bath and Portland stones, so much used in 


Fig. 90.—Oolitic Plants : 
1, Palm; 2, Tree-fern; 3, Cycas; 4, Pandanus; 5, Zamia. 
London and the south of England, being varieties, The limestones are 
burned for agricultural purposes; the clays are extensively developed, 
and receive different names in different parts, and yield alum, sulphur, 
and fuller’s-earth. Ironstone is abundant and good, and furiiehies a great 
part of the iron of Yorkshire, being eleven feet thick. The coal is 
1 From Greek con, an egg, and pit hos, a stone, 
