58 
Geology and Physical Geography : 
of other forms of sedimentary rocks and contemporaneous traps 
(felsites, raelaphyres, &c.). Ilnge masses of coarse dark-red 
breccia-conglomerate are here and there to be seen lying loose on 
the Silurian rocks near the boundary between the two formations. 
In following up the Avon River to its sources near Mount 
Hump aud Mount Wellington, I obtained a tolerably plain 
descending sequence of layers from the lepidodendron beds through 
various thick and thin bedded conglomerates, sandstones, and 
shales, down to conglomerates (containing boulders of mela- 
phyre) under which lie bedded felsites and raelaphyres, finally 
underlaid by coarse grey conglomerate resting against the 
Silurian. (Fig. 19.) 
Of the igneous rocks associated with the Upper Palaeozoic 
sedimentary beds in the valley of the Avon, some are clearly 
contemporaneous whilst others may bo intrusive. The examina- 
tion made has been of too cursory a nature to enable reliable con- 
clusions to be arrived at. 
In their lithological character they are most interesting. Those 
that are unmistakably contemporaneous are principally melaphyres, 
exhibiting various degrees of alteration, due to natural chemical 
action. (Fig. 20.) 
Fio. 20. 
Section showing apparent sequence of beds in head of branch of the Avon 
River S.E. from Mount Ilump. 
In some of them the basaltic character is still recognisable, 
while in others the original structure is quite obliterated. They 
evidently represent the results of the volcanic activity of the 
period. Besides raelaphyres there are quartz-porphyries, felsites, 
&c., of various kinds. The summit of the western bluff of the 
Mount Wellington Range is composed of fine quartz felsite; and 
specimens of serpontiuo and diallage rock Lave been brought from 
the country lying to the north. The results of microscopic 
examinations made of some of these rocks, by Mr. Ilowitt, will be 
found in the Geological Progress Report No. V., page HI and. 
following. 
