Speight and Wild. — Weka Pass Stone and Amuri Limestone. 81 



(2.) Greensand layer : This is loose, calcareous but strongly glauconitic, 

 8 ft. thick, without nodules as far as could be seen on the face 

 of the steep cliff, and passing up into 



(3.) Glauconitic arenaceous limestone, 12 ft. thick, resembling Weka Pass 

 stone but rather more sandy. 



(4.) Grey marl : This succeeds (3) with perfect conformity. Its thick- 

 ness cannot be estimated, since the highest shore-platform has 

 been cut in it. 



The upper layer of Amuri limestone contains borings filled with green- 

 sand, and the marl also contains borings filled with marl. 



Stonyhurst, in a Creek near the Homestead. 



This place was visited in order to obtain observations of the section 

 recorded by Hutton (1885, p. 271). It is unfortunate that he does not give 

 the precise locality, but a careful examination of the creek in the neighbour- 

 hood of the station showed that only one section in the course of the stream 

 was possible, and a description of this is given below. Hutton's remarks 

 are, however, very important. He says, " Here the Amuri limestone is 

 overlain by grey sandstone, probably the representative of the Weka Pass 

 stone. Between the two rocks is a bed of conglomerate formed by sub- 

 angular pebbles of slate. At first sight all three appear to belong to one 

 system, but a close inspection shows that the surface of the limestone is 

 fissured, and that the sandstone penetrates through the conglomerate into 

 the limestone. This, however, may be due to chemical erosion." 



The special importance of these remarks is that they contain a record 

 of pebbles of greywacke along the junction ; it is extremely likely that 

 these pebbles are phosphatic nodules, since at times the latter closely 

 resemble greywacke in external appearance. It is unfortunate, therefore, 

 that Hutton's precise locality cannot be determined. 



In the creek near the homestead the beds lie very flat, and are obscured 

 by surface accumulations and vegetation. At one place a clear section was 

 seen, the only one occurring in the creek. Its record is as follows : — 



(1.) Typical Amuri limestone, striking north-east, and dipping south- 

 east at an angle of about 25°. 



(2.) Nodular layer, 6 in. thick, with the usual characters. 



(3.) Calcareous greensand. This passes up into 



(4.) Weka Pass stone of more than usually glauconitic character. 



The locality is disturbed by faults, but away from the disturbance the 

 dip and strike of the Amuri and greensand limestones are identical. 



Motunau River. 



An excellent section through the whole series is to be seen in the lower 

 course of the Motunau River, and the limestones are well exposed in its 

 limestone gorge about two miles from the sea. The beds strike here north- 

 north-east, and dip east-south-east at an angle of 20°, the whole being 

 absolutely conformable. The sequence is as follows : — 



(1.) Amuri limestone, with typical macrostructure, its estimated thick- 

 ness being 300 ft., the upper 4 ft. with borings filled with green- 

 sand. 

 (2.) Nodular layer, 3 in. to 4 in. thick, composed of subangular nodules 

 in a matrix of greensand ; the nodules are up to 3 in. in diameter, 

 dark-blackish-green in colour, with brown shade inside ( \ Hutton's 

 greywacke pebbles). 



