THO>rsox. — Geolocpj of Middle Clart7ice and Ure Valleys. 323 



of volcanic rocks in Limestone Hill. Unfortujiately, neither here nor in 

 the Clarence River was the base of the series observed. If this great 

 outcrop of Notocene rocks terminated to the north-west along a fault-line 

 one would not expect Clarentian rocks except along its south-eastern 

 boundary. 



There must be a nearly complete section through this Notocene outcrop 

 where it is crossed by the Clarence River, but as the river here flows in 

 a gorge it cannot be closely followed. McKay describes the section as 

 follows : *' The lowest beds are sandstones and conglomerates, containing 

 marine fossils. . . . These fossiliferous sandstones are overlaid by a 

 considerable thickness of volcanic rocks, varying from 50 ft. to 200 ft., 

 and these in turn by sandstones, conglomerates, and shales, followed by 

 a second series of volcanic rocks overlaid by the limestones and grey marls 

 closing the sec|uence." 



The fossils collected by McKay were determined by Woods as follows : 

 Trigonia gh/ptica, " Modiola " kaikourensis, Thracia s]i., and Belemnites 

 supersles. 



The base of tlie Clarentian is not here exposed, and it is cpiite possible 

 that coal-measures are present. The lowest rocks I observed were grey 

 sandstones about 26-30 ft. thick, with occasional pebble-beds, striking 

 north, and dipping 25° to the east. These are followed by about 40 ft. 

 of thin-bedded sandstones alternating with mudstones, and then about 

 300 ft. of massive sandstones with pebble - beds which are sometimes 

 fossiliferous. The pebbles consist of quartzite, greywacke, grey gritty 

 sandstones, jasperoid c|uartz, and occasionally quartz porphyry. The fossils 

 collected included a belemnite, Trigonia gh/ptica, " Modiola " kaikourensis, 

 Thracia sp., AporrJum s]). and other gasteropods, and Bentalium sp. 

 Evidently these are the beds from which McKay collected. 



These beds are succeeded by a fine-grained basalt, here 50-60 ft. thick, 

 with large amygdaloidal masses of calcite containing quartz crystals in 

 druse cavities. This is separated from an upper lava or series of lavas 

 by 30--40 ft. of sandstones. The upper lava is scoriaceous at tlie base, 

 and porphyritic. Its thickness could not be exactly estimated, owing to 

 faults and slips, but appeared to be upwards of 200 ft. It is followed by 

 a bed of mudstone, about 20 ft. in thickness, fiUl of volcanic material, and 

 this again is followed by a third lava, fine-grained and more decomposed 

 and at least 20 ft. thick. The dip of the beds at this point has flattened 

 or appears to have flattened owing to the river flowing along the strike. 

 The next-higher beds appear to be soft sandstones with ironstone con- 

 cretions, dipping steeply. There appears to be a great thickness of these 

 beds and further lavas before the limestone is reached, but the section was 

 not followed. 



On the opposite side of the Clarence River, in the Red Bluff, the section 

 is similar except that the third band of lava was not observed. The top 

 of the second lava is followed by upwards of 40 ft. of mudstones and thin- 

 bedded sandstones. 



The Amur i Limestone and Weka Pass Slo)te. 



The rocks in the Middle Clarence Valley termed collectively the Amuri 

 limestone are lithologically similar to the limestone of Amuri RlufT, and 

 occupy a somewhat similar stratigraphical position, but they have a very 

 much greater thickness and probably represent a greater range of time. 

 Geographically they are nearly continuous with the limestone of Kaikoura 



11* 



