Thomson.- — Geology .of Middle, Waipara and Weka Fetss District . 351 



The mudstones down into whicli the grey limestone passes are variable 

 rocks, being in places ordinary dark-grey mudstones, in others very glauco- 

 nitic mudstones, but for the most part consisting of a mudstone matrix, 

 blue when freshly broken, white when weathered, containing small and large 

 nests of glauconite in large grains. They thus resemble considerably the 

 saurian sandy mudstones, but are more argillaceous and glauconitic. There 

 appear to be about 300 ft. of these beds above the large river-meander on 

 the south bank, and probably a greater thickness between the mouth of 

 Birch Hollow and the limestone gorge on the south side. Foraminifera are 

 abundant throughout, but are mostly rotted. Shell-fragments are present 

 in a few places, while fish-scales and vertebrae and obscure plant-remains 

 are fairly frequent. In the cliffs on the north bank of the river below Birch 

 Hollow crushed tubes of Teredo are not infrequent, but no other shells were 

 obtained. From a cliff" on the east side of the small creek on the right bank 

 I obtained a number of fragments of brachiopods. It is eriiinently desirable 

 that as complete a collection as possible should be made from this horizon. 



Fig. 5. — The Amuri "fucoid." 



BelVs Creek, Bohifs Creek. — In the upper part of Bell's Creek, and in 

 a small tributary which has cut a gorge through the Amuri limestone, 

 the lower, grey limestone and the underlying glauconitic mudstones are 

 exposed in a number of small cliffs, not furnishing a connected section. The 

 glauconitic mudstones resemble those in the Waipara River, and contain 

 large and small Foraminifera* fish-scales, and various spines and spicules, 

 but no shells were obtained except a single fragment of a brachiopod. Near 

 the base these rocks contain numerous rounded white and green quartz 

 pebbles up to J in. diameter, and small rounded pieces of retinite up to 

 I in. diameter. 



Weka Creek. — The Waipara greensands are not exposed in the main 

 branch of Weka Creek, owing to a slip of limestone overlying them, and 

 the succeeding glauconitic mudstones are also mostly obscured. The upper 

 12 ft. of the latter bed is exposed in the cliffs of a small creek entering 

 from the west just above the limestone gorge, and consist of dark mudstones 

 with nests of glauconite similar to that below the Amuri limestone in the 

 Waipara River. They are directly succeeded by the marly limestone, of 

 which about 30 ft. is exposed. The same mudstones occur in the bed 

 of the Weka Creek at the junction of this tributary, and yield fish-scales 

 and vertebrae and Foraminifera. 



