143 



The Assistant-Secretary mentioued fhat tlie tube con- 

 structed by the Seplalis is often over eigbteen incbes in 

 lengtb wbere tbe eucalypts in tbe roots of wbicb tbey bored 

 are growing in deep sandy soil near tbe banks of creeks. Tbe 

 Cossus ciiiereics, anotber goat-motb, is very destructive, as 

 migbt be seen anywbere on tbe Park Lands, and especially 

 between tbe Stag Inn and Smitb's Brewery, wbere some of tbe 

 trees bave scarcely an incb of sound wood in tbeir trunks and 

 limbs. Tbe motb comes out of tbe boles, wbicb are in an 

 upward direction, and consequently tbe rain-water enters and 

 causes tbe beart-wood to rot. Witbiu tbe past few weeks be 

 bad observed tbat four large branches bad been broken off 

 tbrougb tbe ravages of these insects. 



Geology. 



N'ofes 0)1 the Geology ahoiit Frankliij^ HARBorR, tvest side of 



Spencer's Gulf. By Frofessor B. Tate. 



Tbe area under observation is about twelve miles from we^ 

 to east, and about eight miles from north to south, and com- 

 prises much of the Hundreds of Playford and Mann, and part 

 of Hawker. 



" Pleistocene consolidated sands," with travertine cover, and 

 " Eecent sand dunes," occupy tbe seaboard. 



" Eecent marine shell-beds" skirt the almost land-locked 

 sheet of water known as Franklin Harbour ; they are but 

 slightly elevated above ordinary high tides, and their extent is 

 pretty well defined by the growth of mangrove and samphire. 



" Pliocene Drift" extends from the coast to about five miles 

 inland, and consists in the lower levels of sandy loam, but 

 becomes clayey and stony near the bills. 



Xo perennial streams exist in tbe hills, but the broad and 

 deep watercourses excavated in tbe Pliocene Drift would suflice 

 for rivers of large magnitude. Tbe deep ravine of the Oola- 

 bidnie Creek displays some magnificent sections in the Pre- 

 Silurian rocks, as also tbe thickness and character of the 

 marginal accumulations of the Drift period. 



" Pre-Silurian" metamorphic rocks constitute the ranges or 

 bill region. The prevailing rock is mica slate, with which are 

 associated hornblende schists, quartzose felsites, quartzites, 

 and gneiss. The iuterstratification of crystalline albite and 

 ortboclase felspars, so well exposed in the Oolabidnie Creek, is 

 noteworthy ; white marbles occur on tbe east flank of Mount 

 Parapet and at Wangaraleednie. ]S'arrow granite dykes 

 abound — the constituent minerals being albite, quartz, and 

 hornblende ; the last in prisms, not unfrequently of large 

 dimensions. 



