LATE PALAEOZOIC FOLDING IN THE HUNTEK KIVEK DISTRICT. 129 



strata north of the Hunter, in this particular district, were 

 coutinuous with those south of the Hunter. 



In the reconstruction of the folds careful attention has 

 been paid to the varying degrees of development at different 

 localities, exhibited by the various strata, as, for example, 

 the Dempsey beds, which apparently are a localised series. 

 The text of Professor David's memoir has been of constant 

 help in supplying many of the details which were needed 

 in working out the reconstruction. Concurrent with the 

 appreciation of the variable development of some of the 

 strata has been the recognition of the tectonic history of 

 the lower Hunter area during Permo-Carboniferous time. 

 The overlaps referred to above have been carefully con- 

 sidered, and the fact that the Lochinvar dome had already 

 begun to rise before the Upper Goal Measure swamps had 

 reached a big development has been borne in mind. On 

 account of this pre-Newcastle bulging it seems fairly cer- 

 tain that the Newcastle Coal Measures only flanked these 

 initial folds. 



In the estimation of the crustal shortening the base of 

 the Bolwarra conglomerate was chosen for measurement. 

 This horizon was followed throughout all the folds with a 

 rota-meter, its original length before compression thus 

 being obtained. This conglomerate, the lowest division of 

 the Muree beds, constitutes an admirable horizon for the 

 purpose in question for the following reasons: — it shows 

 uniform development over the whole of the area, giving 

 good outcrops in the field. In addition, it has probably 

 behaved the most uniformly of any of the strata throughout 

 the folding, being essentially a competent horizon. Further- 

 more, from the stratigraphical details exhibited in the 

 field and recorded on the section, it is seen that the vertical 

 interval separating the base of the Muree beds from the 

 upper surface of the Greta coal measures is fairly constant, 



I -August 3, 1921. 



