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curious variety of this substance was discovered in Powis Villas, much 
like the stem of a tree, with a ligneous appearance around it, as if its 
bark had been transformed into that substance. Tabulated masses of 
flint have also been found about ? of an inch in thickness, resembling 
silicate of iron, giving the idea that a stream of silica and iron had 
become solidified at the bottom of the cretaceous sea. 
No. 6. Embedded in this deposit are brecciated masses of in- 
durated clay, flints, and gypsum, with crystals of selenite, varying in 
form and colour, and which penetrate the whole mass. Some have 
undergone intense chemical action, leaving orifices upon the surface 
through which the gas has bubbled and escaped. Others, coated with 
a coaly substance, resemble honeycomb. In some specimens, 
crystals spangle the smooth surface of the flints, and are of a frosted 
appearance. Others have botryoidal and ‘reniform crystallizations, 
coated with a delicate bloom, ranging from yellow to olive green. The 
-prettiest variety of gypsum was found in Montpellier Crescent : it is 
variegated, the crystals being of a needle-like and cob-web form ; 
others are flat and several inches in length. Some of these specimens 
sparkle as if diamond-dust had been scattered over their surfaces. 
These excavations show that the heterogeneous mass was derived 
from the beds of the plastic clay; while the lithological character of 
the beds marked by the breccia, aluminite, hydrate of alumina, 
gypsum, and clays of the Lower Tertiary, determine its geological 
place, 
Nature works by simple laws, and the results are truly wonderful. 
A great portion of the soil owes its origin to decomposed organisms, 
In this soil, therefore, there is sulphuric acid, which is conveyed by 
rain down to the clay, ironstone, and chalk, through which it per- 
colates and metamorphoses the clay into sub-sulphate and hydrate of 
alumina, and the chalk into gypsum and crystals of selenite. In the 
chalk rubble lie breccia and ironstone, ornamented, by the marriage of 
sulphuric acid and chalk, with crystals of every variety, form, and 
colour. Such is the origin of the Temple Field Deposit, lying from 
165 to 220 feet above the level of the sea. 
Stet di en 
