The Geolo[iii of Coivnaidal. 185 



fault. The section exposed by the Creek shows the stratitied 

 iinidstones to be suddenly interrupted by a mass of hard uiistrati- 

 iied boulder-bearing niudstone, and about 20 yards or so in width. 

 <)n the N. side it shows a very clean and decided wall at its 

 junction with the stratified mudstones. On the S. side the 

 junction is observed by recent alluvial and gravels, but doubtless 

 the wall here is just as marked. It would appear that two 

 parallel faults close together have occurred, and the mass 

 lietween has been displaced. We are not in a position to state 

 definitely whether this mass of rock moved downwards or 

 upwards, but as the displaced bed corresponds very well in 

 character to the second class of our division, we are much inclined 

 to the opinion that it was a downward displacement, and 

 l)robab]y does not amount to less than 50 feet. The harder material 

 of the displaced mass has resisted weathering and denudation 

 Ijetter than the softer sti-atitied nnulstones, and thus a ridge 

 marks the course of the fault across the alluvial plain of the 

 valley. 



Dykes. A considerable nund^er of dykes may be noticed 

 penetrating the glacial beds exposed in the Goodman's Creek. 

 .Some are so decomposed that it is impossible to define their 

 original character ; those in a good state of preservation are 

 composed of basalt, varying in structure fiom medium-grained 

 to exceedingly close-grained. Several small ones occur in the 

 vicinity of Elam's farm ; close to the l)ig fault just described 

 there is a group of six itr seven, wiiile several small ones 

 may be seen near the high blutl'. They run more or less in 

 an E. and AV. direction, and are approximately parallel to 

 the main joint planes which traverse the glacial beds in 

 this locality. The occurrence of a bunch of dykes in close 

 proximity to the fault alluded to above may indicate that the 

 two phenomena are closely related. Sinuhir dykes traverse the 

 glacial beds exposed to the west on the Lerderderg River. We 

 have nowhere observed a dyke passing through the over-lying 

 tertiary beds, and it would tlius appear that this system of dykes 

 is not connected with the CuUengarook basalt which was poured 

 out after the tertiary beds had Ijeen formed, but has arisen from 

 .some centre of igneous actixity lying to the west of the district. 



