28 



THE GEOLOGIST. 



prises the whole of these in various proportions. Melbourne proper, 



with the exception of its extreme 

 western portion, which is situate on 

 an older volcanic formation, is built 

 almost wholly upon May Hill sand- 

 stones and soft laminated shales. 

 The whole of .this stratum has evi- 

 dently been subjected to immense 

 disturbance, it being a matter of no 

 little difficulty to discover a patch 

 many yards in extent within which 

 the beds even approach to a hori- 

 zontal position. The general incli- 

 nation of the stratification more 

 often verges on the perpendicular, 

 whilst numerous contortions, folds, 

 and doublings — theupper edges being 

 cut away by denudation, at the same 

 time that the lower are hidden far 

 below the exposed portion — offer an 

 interesting but withal most difficult 

 problem to the geological student. 

 Very many of these contortions 



Fig.l. — The shaded portion issnurian; 

 the very dark tint, Granite ; the dotted, 

 Tertiary, and Tertiary covered by basalt. 

 The references are : — 1. Arthur St. 2. 

 Mt. Martha. 3. Mt, Eliza. 4. Yowanes. 



may perhaps be explained by the supposition of alternate elevations and 

 depressions, but not a few are so intricate as to provoke queries by no 

 means admitting of an easy answer. 



In some of the yet unpaved streets of the metropolis, for example, pro- 

 truding edges of the shales resemble the piles of slates, seen from above, 

 in a stone-mason's yard. Opposite the Supreme Court, several bends in 

 the strata suggest the idea of a loosely-bound book forcibly pressed toge- 

 ther from the two ends ; the inner and concave side being puckered up, 

 whilst the outer curve is correspondingly stretched and fractured. In a 

 fine section afforded by a cutting in Studley Park, the beds are nearly ver- 

 tical, leaning towards each other above a pretty clearly developed anticlinal; 

 such anticlinal, however, would seem rather to have been caused by lateral 

 compression than by simply upheaving forces acting from beneath. At Keilor, 

 • a township about ten miles on the 



3 ir^<f^4^r P ^ 



Fig. 2. — Bend in strata at Keilor, opposite side 

 of valley to that represented by PI. II., and near 

 the spot whence the latter was taken. 



road to Castlemaine, a natural 

 section displays contortions not 

 unlike the letter S reversed and 

 placed horizontally (part of this 

 curve is shown in the annexed 

 sketch, PI. II.), traces of the 

 bend being distinctly visible on 

 the opposite sides of the valley, 

 — one of denudation, — at least 

 200 yards distant. And on re- 

 moving the surface of Collins 

 Street eight or nine years since, 

 arrangements similar to the 



ground plan, Fig. 3, presented themselves, none of which seem capable of 

 being accounted for by simple geological forces acting vertically. 



A somewhat remarkable feature of the strata referred to, is the frequent 

 protrusion of Elvan dykes. Several of these masses are represented on 

 the map by waving lines. Prom the condition of the closely adjacent 



