52 '£ r<tiisactio)is. 



limestone at Amini Bluff, where it is less than 800ft. thick, in view of the 

 lithological similarity of the limestones in the two localities. It appears 

 that depression and deposition commenced in the Middle Clarence area 

 at an earlier date than farther south, and continued in this area while it 

 gradually spread farther south (and probably north). A confirmation of 

 this view will ensue if the Amuri limestone in the Puhipuhi Mountains, 

 between Kaikoura and Clarence Mouth, is found to be intermediate in 

 thickness between that at Amuri Bluff and that in the Middle Clarence 

 area, and if fossils from the underlying Cretaceous beds, none of which 

 have been available to send to Mr. Woods, prove to be inteiiuediate in age 

 between Senonian and Cenomanian — i.e., Turonian. 



II. Distribution of the Flixts. 



Small rounded flints similar in manner of occurrence to those of the 

 English Chalk occur fairly abundantly embedded in the limestone at Amuri 

 Bluff.* They are generally of a light-brown or flesh colour, but are some- 

 times opaque white and hardly disthiguishable from the limestone in which 

 the}' occur. Unlike the English flints, they are never hollow, thus destroying 

 any hopes of discovering sponge-spicules or other fossils in their interiors ; 

 nor does the surroimding limestone exhibit the hollow casts of sponge- 

 spicules which are often so well displayed in the Chalk. In the Middle 

 Clarence and the Ure River area similar flints are found in the upper part 

 of the limestone, but in the lower part an entirely different mode of occur- 

 rence prevails. The base of the limestone is entirely replaced by beds 

 which are composed of large lenticules of black flint in the centre, with a 

 variable amount of grey external matter, very often composed of euhedral 

 crystals of a cai'bonate set in a flint mati'ix. 



These flint-beds were first described by McKay (1877) from the Hapuka 

 River, a little to the north of Kaikoura, where he found '' 20 ft. of a peculiar 

 rock consisting of flinty nodules in a matrix of dark shale " between sandy 

 micaceous (Cretaceous) clays and the base of the limestone. This appears 

 to be the southernmost point of their range. At Waipapa boat-harbour, 

 farther to the north, they are 50 ft. m- more in thickness, and are de- 

 scribed by McKay (1886) as " foimed by black flint in layers averaging 

 about 6 in. in thickness, which are parted by a lesser thickness of white 

 decomposed flint, or fine-grained sandstone." Tliey have not been studied 

 in detail between Clarence Mouth and Kekerangu. but are described by 

 McKay (1886) as of " very considerable thickness "" in the Benmore Stream, 

 and here he notices the light-coloured exterior to the flints in their upper 

 part. From this point the Amuri limestone swings round in a great curve 

 through Benmore. the Isolated Hill, and Brian Boru. leaving its former 

 course approximately parallel to the coast to enter the Middle Clarence 

 Valley (c/. Cotton, 1913; Thomson, 1915). In the Isolated Hill Creek, a 

 tributary of the Ure River which separates Benmore from the Isolated 

 Hill, a very good section of the flint-beds is displayed. They are about 

 400 ft. thick, and are perfectly conformable to the underlying nmdstones, 

 into which the}^ pass almost imperceptibly within a thickness of 2 ft. of 

 rock. Forty feet below the main mass of flints there is a thin intercalation 

 of flint anci flint-carbonate rock within the Cretaceous mudstones. At 

 Coverham, in the Middle Clarence Valley, a few miles to the south-west. 



* Cj. Hutton (1877), Hector (1887), Liversidge (1877). I have not seen any flint 

 in the Amuri limestone of the Waipara district. 



