332 Morris Morris: 



nong, and its northern boundary running in a similar direction 

 about one mile north of Lilydale. Lateially, it reaches from about 

 Mooroolbark in the west to near Wandin in the east. 



From Mt. Dandenong one looks eastward across the Woori- 

 Yallock basin to the closely related mountains of Healesville and 

 Warburton, northwards to the Dividing Range, beyond the alluvial 

 flats of the Yarra. and westwards and southwards across a dissected 

 plain, sloping towards the coast line. 



It was found necessary to extend the mapping in various direc- 

 tions beyond the limits above defined, but such extensions are 

 omitted, and wdll only be referred to when necessary to illustrate 

 features that already appear in the circumscribed area. 



II. — Previous Work. 



In 1856 Sir A. II. (J. Selwyn (1) made a brief description of Cave 

 Hill, near Lilydale, where he found "the entrance to a cave 120 

 feet deep," which eventually became the site of Mr. Mitchell's lime- 

 stone quarry. 



In 1892-3 Rev. A. W. (Jresswell, M.A. (3, i), wrote two papers, both 

 of which deal almost solely with the fossiliferous contents of the 

 Cave Hill limestones. 



It was not till six years later that any work was connnenced on 

 the stratigraphy of the district. In 1899 the late V. R. Stirling (8) 

 published a brief description, and made a map, of Cave Hill and of 

 a narrow strip of the district contiguous with it eastward as far as. 

 Lilydale, and westward across the railway line, where it embraces 

 a small residual plateau capped with basalt. He failed, however, to 

 recognise the important series of igneous rocks which flank Cave 

 Hill on the east, and which, togetlier with those of an earlier 

 series, form the surfaci: rock of Lilydale. These he called meta- 

 morphosed Silurian strata, being betrayed by a most deceptive 

 resemblance which they bear to an indurated shale. 



These two igneous series possil)iy bt-loiig to the opening move- 

 ments of a great cycle of igneous activity, which culminated in the 

 piling up of the Dandenong Rages. The remains of this system. 

 which occupy the greater part of the area icpresented <in the nia{>. 

 foi-m the most conspicuous feature of the district, and will l)e the 

 chief subject of this paper. 



During 1910 I mapped and descril)e(l the aiea eontained in a 

 triangle, whose apices are Mooroolbark, Lilydale and Evelyn. 

 The present map and p;iper are an extension of these earlier unpub- 

 lished observations. 



