Mines and Mineral Statistics, 
11 
Surrounding the tree is a soft substance, 2 inches thick, which was 
probably the bark. Small masses of yellowish earth are also scattered 
through the same layer of basalt. The rock above this is full of 
amygdaloidal cavities, containing large double hexagonal p^waniids of 
that rare ;ieolite. IlerslietUe, together with calcitc and minute crystals 
of analcinie. I have also seen large radiating crystals, several inches 
in length, of arragonitc from the trap of this locality. 
The columnar structure which basalt frequently assumes may be 
observed in the rock marked a in tbc above sketch. The basalt has 
liere rudely c*rystalli;!cd in vertical hexagonal and pentagonal columns ; 
indeed the flat surface of the rock across the river bed has the ap])ear- 
ance of a roughly formed pavement of live and six-sided blocks of stone. 
In anotlier dill section, about 2- miles further up the river, the 
basalt lias a I'adiated columnar structure, llio narroAv columns radiating 
like the ribs of an open fan, and giving to the cliff a vei*y ])icturesque 
appearance. 
At iXewstead Station the. basalt contains abundance of olivine, in 
small roundish ma.sses, composed of au aggregate of angular grains of 
red, yellow, and green colours. AAius of wliite jasper, several inches 
thick, are also uot nncommou in this rock. 
Near Auburn Yale Station the basalt is of a tracliytic cbaracter. 
It has been before remarked that outliers of the A’ulcanic trap occur 
in places throughout the district. These outlylug vestiges of a once 
overspreading formation now testify of the vast denudation the laud 
has undergone since the pliocene period. (See fig. 2, d d.) 
Miocene. 
The rocks of this period are of much economic importance, on 
accouut of the valuable deposits of stream tin which some of thina 
contain. 
Certain of tlicse rocks are full of impressions of leaves and plant 
stems, which are believed to bo of lower miocciie age ; but I shall 
refer to them hereafter. 
The formation must have been of considerable thickness, and seems 
to have once covered nearly the whole district, for it is foiiULl on the 
summits of liills, and again filling some of the intervening depressions. 
The upper part consists of sandy comu’etionavy ironstone, whicli some- 
times assumes a pisolitic structure, from the small ferruginous con- 
cretions composing the mass. Where this is the case, the surface of 
the ground is often strewn with small round ironstone pebbles of the size 
of a pea. Tlie ironstone is now ehielly found in outliers forming those 
“red hills,” as they are locally called, which constitute such marked 
features in the country between the Macintyre ami Cope’s Creek. 
Underlying the ironstone are red and white sandy clays, aud beneath 
these waterworu drift and conglomerates, the latter usually oeeiq^ying 
the sides and bottoms of the ancient valleys, and containing the tiii- 
bcaring deposits. 
Owing to the enormous denudation this formation has suflered, the 
overlying clays and ironstones have in places been entirely removed, 
leaving the stanniferous gravels exposed near the present surface, and 
therefore easily accessible to the miner. Such is the case at the 
Elsinore, Stannifer, aud other important tin mines. 
