328 Albert V. James: 



Headward Erosion. — The extremely youthful tributary streams: 

 frequently become gorge-like, and tend to cut back across the 

 fields. Farmers in this locality meet the problem by piling boul- 

 ders at the head of the tributary and planting hardy shrubss 

 around them in order to check the velocity of the water, and thus 

 retard the transport of material. Ilie early neglect to check 

 the headward erosion of youthful streams has led elsewhere to- 

 great loss of land. A large area at Goburg has been rendered un- 

 fit for habitation within the last thirty years, and the same will 

 occur at Aberfeldie, near the Essendon sand pits, if preventive- 

 measures are not taken soon. 



Near the school at Bulla an extremely young active. tributary 

 has cut back from Deep Creek and formed a canyon in decomposed 

 granodiorite and basalt. Apparently no effort has been made tO' 

 check the headward erosion, and now it is completely out of hand, 

 and threatens the roads north of Bulla. The canyon is about 

 60 ft. in depth. It iis not likely to deepen further for many years ^ 

 as its floor is nearly adjusted to the present level of Deep Creek. 

 Lateral erosion is now rapidly increasing the area of destruc- 

 tion. 



Basalt Outliers. — A small outlier is seefii in the south of the- 

 large granodiorite outcrop, and another in the extreme centre- 

 north in Ordovician sediments. They represent small basalt 

 tongues that have been cut off from the main lava sheet by river- 

 action. 



Palaeozoic Rocks. 



General Description. — The l>edrock of the area so far as is 

 known consists of Upper Ordovician and Lower Silurian sedi- 

 ments in the form of shales, sandstones, conglomerates, quartzites, 

 slates and hornfels. These have been strongly folded by approxi- 

 mately east and west pressure, and the prevalence of easterly dips 

 suggests overfolding to the west. The folds pitch to the north, 

 and this pitch makes the strike of the strata somewhat irregular. 



Throughout the district these palaeozoic rocks have been highly- 

 fractured and faulted, most of the faults being reverse strike- 

 faults. On the left bank of Deep Creek, at the mouth of Hanging 

 Valley, is a fault breccia altered to hornfels by the granodio rite- 

 intrusion. 



If the conglomerate (C^), near Hanging Valley, and conglom^ 

 erate Cj or C.^ on Jackson's Creek, be parts of the same stratum,. 



