The South Australian Naturalist. 
15 . 
IV. Geological. 
The Mount Lofty Ranges are formed of some of the 
most ancient rocks known, chiefly of Cambrian and Pre-Cam- 
brian age. Howchin (1) has described very fully the geology of 
the Ranges and Osborn (2) has given four main types of soils 
in which E. obliqua grows. They are (a) quartzite soils, (b) 
Ironstone soils, (c) glacial deposits and (d) gully soils. Except 
in the soil of the glacial areas our species under review grows to 
forest dimensions. Forests on quartzite soils attain their maxi- 
mum development and form the typical tree vegetation of the 
Ranges in the area defined by the 30 inch Isohyet. Teale (3) 
gives a description of the Geology and chief soils at the Kuitpo 
Forest where a fair proportion of stringybark grows. The rocks 
are of Cambrian and Pre-Cambrian age, the former having soils 
of a gravelly sandy loam and a red gravelly clay loam and grow- 
ing good stringybark. The latter series of rocks producing a 
grey gravelly loam support poor stringybark except in the gullies. 
The Tertiary to recent deposits produce good E. obliqua forest 
in loose deep sands and light yellowish-red sandy clay loam. 
V. Ecological. 
The ecology of the stringybark {E. obliqua) forest 
is a very big subject and has been best deal with by Osborn (2) 
who gives a list of 210 plant species occurring in this formation. 
The chief tree species associated with E. obliqua are E. capi- 
tellata, E. viminalis, E. rubida, E. fasciculosa, E. cosmophyllaj 
E. rostrata, Acacia vielanoxylon, Exocarpus cupressiformis and 
Casuarina stricta. Of these plants only one {E. viminalis) is at 
all abundant and generally forms a pure stand. The others are 
only of occasional occurrence leaving E. obliqua the dominant tree 
in all the forest of 1300 feet or over. It is remarkable how this 
one tree dominates the timber growth on the higher levels of the 
Mount Lofty Range. The shrubs, undershrubs and smaller plants 
are exceedingly numerous in the stringybark formation. The 
chief shrubs arc Pultenaea daphnoides , Acacia myrtifolia, Hakea 
rostrata, Leptospermtim myrsinoides, L. scoparium, and Ixodia 
achuleoides and these are abundant In certain situations and dom- 
Of the smaller shrubs Epacris impressa, 
rlatylobium obtusangidum, Tetratheca pilosa, Grevillea lavandu- 
and three species of Hibbertia are found In abundance in 
(1) Trans. Roy. Soc., S.A. Vol. XXVIII (1904), 253^^d 
Ibid XXX (1906), 227. 
(2) Trans. Roy. Soc., S.A. Vol. XLVIII (1924), 99. 
(3) Dept. For. Bull. 6. (1918) 8. 
