Geology of Lily dale 357 



V. -Faults. 



The map shows a narrow band of the series h along the western 

 edge of the system, between the silurian, with which it foruis a 

 broken border on the west, and the series c, with which it forms a 

 very regular junction on the east. This latter junction has such 

 uniform persistence in direction over a course of seven miles, as 

 to need explanation, especially as it is matched about two miles to 

 the east by another very uniform, tliough arcuate lx)undary, w^hich 

 marks the eastern limit of the igneous system, and is for a large 

 part of its course parallel to its western fellow. 



Of these two junctions three explanations j^resent themselves. 

 They are either— 



1. Natural boundaries, or, 



2. Fold junctions, or 

 W. Fault junctions. 



1. The first fails to explain in the case of either of them the 

 uniformity of direction over a long distance, w'hich contrasts so 

 conspicuously with the many indisputable natural boundaries in 

 the map. And when the two cases are taken together, its inade- 

 quacy is still more apparent. 



2. Regarding the second, it has been shown that these igneous 

 rocks lie unconformably on the upturned edges of the Silurians. 

 If, therefore, the igneous rocks were involved in the folding pro- 

 cesses, it can only have been to a small extent, so small that the 

 resultant folds would be too shallow to account for the uniform 

 junctions in question. 



3. The evidence points strongly to the view that they are fault 

 junctions. I have, therefore, interpreted them from this point of 

 view, referring to the western junction as the Montrose fault, and 

 the eastern one as the Evelyji fault. 



The Montrose Fault. — This junction has l)een mapped for seven 

 miles from the Salvation Army farm near Bayswater to Lilydale, 

 and, excepting a small bulge westward, between Montrose and the 

 Olinda Creek, its course throughout may be represented by a line 

 which is very regular and persistent in direction. The junction is 

 not visible all the way, but wherever it can be seen, it conforms to 

 this line. 



The series h, which lies along the west of the junction for the 

 whole distance, may be seen outside of Lilydale, on the east of the 

 junction, underlying the series r. which also contains many in- 

 cluded fragments of it at its base. It follows, therefore, that if 



lU 



