114 
The strata strike, on the whole, from north-west to south-east, the denuded edges 
coming to the surface in that direction. Their dip is usually towards the north-east, 
and at a high angle, approaching the vertical. But the lines denoting the outcrops of the 
strata, as will he seen from the map, bond or “bag” southward along an axial line passing 
to the west of the townshiji of Thoruhorough. It is impossible to estimate exactly the 
thickness of the sorios of strata to which the goldfield belongs, as neither top nor bottom 
has yet been detected, and, moreover, the apjiarent thickness may be exaggerated by 
unsuspected replications among the denuded beds ; but a minimum thickness at least 
may be ai'rivcd at with some confidence by assuming that, allowing for replica,tions, an 
even for possible faults, the average dip to TI.E. is no more than 65°. On this assump- 
tion a thickness of 4,000 foot may be presumed for the strata cropping out between the 
horizon of the Amy Moore Mine and the north-east edge of the large scale map, as 
measured to the south-east of Kingsborough. Measuring downward from this same 
horizon at Peak “N,” in the Mount McOann Range, south-westward to Mount Grant 
(a line where the apparent thickness is not affected by the bending or bagging above 
referred to), a further thickness of at least 17,000 feet of strata is mot with. 
The detailed “ Study in Stratigraphy” which the preparation of the large map 
imidies has revealed nothing to suggest the idea of any break in the continuity of the 
deposition of the whole series of at least 21,000 feet of strata, unless it be the gat enng) 
at^the head of Columbia Creek, of a portion of the series which at the mouth ot 
Caledonia Creek, only five miles distant, measures (at 65° of estimated average dip! 
about 10,000 feet, into a space which can contain, although the strata are vertical, no 
more than 1,300 feet. But I am inclined to think that the phenomenon may be 
explained by a thinning out of the sediments towards the south-east, though possib y 
the effect may be aided by a fault having a downthrow to the north-east. 
The nearly parellel valleys of Caledonia Creek (Glen Mowbray) and the I^dg- 
kinson River are bounded on the right or north-eastern side by the Mount McGann 
Range, and on the opposite side by the Mount Robert Range. These ranges have had 
their trend determined indirectly by the forces which compressed the strata ot ttie 
district from south-west to north-east, and threw them into long folds from south-eas 
to north-west. After the strata had been compressed into nearly as small a compass 
as they would go into— f.e., till they became nearly vertical— the further operation o 
the same pressure resulted In the formation of fissures along lines of weakness, 
which lines of weakness were found in the bedding-planes dividing the upturne 
strata from one another. These fissures, which are nearly, but not exactly, paral e 
with the outcrops of the strata, have been filled^ with a rock of great hardness, 
which, by its power of resisting denudation, has given rise to the Mount McGan 
and Mount Robert Ranges. Both of these ranges occur in zones in which 1 1 
hard rocks in question are closely grouped together, while the intervening 
“country” has been channelled by the llodgkinsou River and Caledonia Cre 
into deep valleys. The material with which the fissures are filled _ forms veins o 
dykes, from three to forty feet in width, of pure silica in almost all of its various forms- 
It frequently resembles quartzite, and occasionally passes into ribbon-jasper or cha c 
dony. The veins are often so laminated parallel to their sides as to suggest that tn ^ 
may be beds rather than veins, but the mode in which they now and then cut across 
adjacent strata, although preserving a general parallelism, sufficiently disproves thistheory- 
Crystallisation is comparatively rare, and the lamination seems to imply deposition 
silica during the passage of copious sheets of hot water charged with the mineral m 
solution rather than the segregation of the silica from the surrounding strata. The v 
(which they hardly are in the usual sense of the word), as laid down on the map, are v 
