Mesozoic Bocks. 
75 
disappear under the tertiaries. They extend only a short distance 
northward from the Wanuon, as at Coleraine they are seen to be 
bounded on the north by the trap rocks, and a short distance 
north of Casterton by the Metamorphic schists. Southward 
they are visible as far as Digby, but their actual extent 
south and south-west is unknown on account of their being over- 
lapped by the wide -spreading Tertiary and Volcanic layers which 
constitute so largo a portion of the surface area of the western 
district. Even in the tract where they are near the surface, 
the Mesozoic rocks of the Wanuon district are so covered 
by thin Tertiary cappings and deep soil that few observations 
can be made as to their character or the inclination of their 
beds. 
Soft earthy sandstones, from greenish brown or drab to yellowish 
white, and earthy or gritty shales, appear to be the prevailing forms. 
Imperfect plant-impressions arc numerous in many of the bands, 
and some distinctly recognisable forms have been obtained. Seams 
of somewhat impure coal occur in the measures at Coleraine. 
This portion of the country consists of beautiful open downs of 
great fertility, and affording rich pasturage. 
The area occupied by exposed Mesozoic rocks in the Cape 
Otway district is bounded on the south-west and south-east by the 
coast line from near the mouth of the Gellibrand River to between 
Loutit. Bay and Barwon Heads, and on the inland side by the 
flarrjdng Tertiary deposits from the mouth of the Gellibrand to a 
few miles south from Colac, and thenco round to the coast. The 
Mesozoic rocks of the Barrabool Hills, near Geelong, form portion 
of, but are separated as surface rocks by, overlying tertiaries from 
those of the Otway Ranges. 
Like the Mesozoic rocks of the Wannon, those of the Cape 
Otway Ranges and Barrabool Hills consist principally of sand- 
stones and shales with occasional coarse gritty beds composed of 
granitic detritus and line conglomerates containing pebbles of 
granite, syeuite, porphyry, metamorphic slate, and micha schist. 
At the Barrabool Hills the conglomerate beds contain pebbles of 
the underlying diallago rock in the vicinity, and Mr. C. S. 
Wilkinson also found in them pebbles of Silurian slato containing 
well-preserved graplolites . The colour of the sandstones varies 
from nearly while to dark greenish-grey or yellowish-brown ; the 
texture is generally soft and earthy, though sometimes hard 
durable sandstones are met with. 
Throughout the whole series plant-impressions and very thin 
irregular seams of coal are common. 
The dip is very inconstant, and the rocks aro much faulted and 
unevenly bedded. Large and small nodules or indurated lumps, 
sometimes calcareous and sometimes ferruginous, are common in the 
sandstone. Distinct lines of stratification arc often discernible 
