422 



Transactions. — Geology. 



Shoal Bay, and could be continued for upwards of two miles 

 before reaching high ground. The following diagram will 

 furnish a further explanation of this theory : — 



Fig. 4. 



Suppose CG to be the line of fault. Then if the down- 

 throw occurred on side A, and subsequent denudation planed 

 the whole surface level, the band would appear displaced at 

 E and F as shown, the surface at D representing the low 

 ground between the two outcrops. Furthermore, the amount 

 of lateral displacement would increase and that of vertical 

 displacement decrease with the angle of hade. A normal 

 strike fault hading at a large angle would cause the necessary 

 lateral displacement with a relatively small amount of throw. 



It would seem, therefore, that the exposure occurring at 

 Cheltenham Beach, marked CD (fig. 3), is undoubtedly con- 

 nected with that marked E, which is almost to a certainty the 

 same band as the one outcropping further north at F. 



Mr. Park states (page 5) that the strike of the Judge's 

 Bay bed would carry it to Cheltenham Beach. This may be 

 so," but the bed at Judge's Bay dips west, whereas that at 

 Cheltenham Beach dips east. Besides, the strata at Chelten- 

 ham Beach are so disturbed as to render their correlation 

 with those occurring at Parnell a matter of extreme diffi- 

 culty ; indeed, no stratigraphical connection can be estab- 

 lished between the beds on the opposite sides of the har- 

 bour. Considerable difference, moreover, is to be found in 

 the material composing the beds at the two localities. At 

 Parnell the deposit shows plenty of Maitai slate, contains 

 no larger fragments and extremely few fossils ; whereas at 

 Cheltenham Beach the grit is coarser in character, in places 

 merging into conglomerate, is distinguished by numerous 

 blocks of andesite, and is fossiliferous throughout. 



From Cheltenham Beach north the strata consist of the 

 ordinary sandstones and shales, these being overlaid at Taka- 

 puna Beach by a stream of basaltic lava from the old crater 

 which is now occupied by Lake Takapuna. About a mile 

 north of this crater-lake the ash-beds again appear in the sea- 

 cliffs, lying, as before, conformably between other beds of the 



