60 Transactions. 



of the entrenchment seems desirable. This may be found in the fact that 

 during the Recent period the sea, as shown by the cliff, has cut away several 

 miles of land, thus shortening the course of the Patea River, and allowing 

 it to deepen its channel for some distaiice above its present mouth. 



Geology. 



The stratigraphical geology of the Patea district is very simple. Almost 

 horizontally-bedded claystones, known in geological literature as the Patea 

 blue clays, are unconformably overlain by beds of gravel and sand belonging 

 to Thomson's Hawera series. A small patch of gravel and sand forming 

 a low hill in the Patea Valley east of the town bridge is probably quite 

 distinct from the Hawera beds. Sand and silt form the surface of a low- 

 lying flat near the mouth of the Patea River. Of more importance are 

 the iron-bearing dune-sands that cap the sea-cliffs and extend for some 

 distance back from their margin. 



Patea Blue Clays, &c. 



The Patea claystones are of the type which throughout New Zealand 

 is popularly called " papa." Like the Wanganui clays, they contain a 

 considerable amount of fine micaceous sand, which, according to the view 

 expressed by Marshall and Murdoch in their paper on the Tertiary rocks 

 of the Wanganui district (10, p. 118), was probably derived from the granites 

 of north-west Nelson. Some layers consist almost entirely of fine sand, 

 and in places these may be crowded with shells. The claystones are 

 exposed only along the coast-line and in the Patea Valley, where, as 

 previously mentioned, they form cliffs on either side. A thin bed of lime- 

 stone outcrops on both sides of the Patea Valley between Kakaramea 

 Railway-station and Pirinoa Pa. This is probably at a lower horizon than 

 the Nukumaru limestone. 



During his visit to Patea last October the writer collected the following 

 fossils from shelly layers in the sea-cliff half a mile to a mile north-west 

 of the mouth of the Patea. The identifications have been made by 

 Mr. John Marwick. Living species are marked by an asterisk : — 



Ancilla sp. 



Crepidula gregaria Sow. 

 Dentalium solidum Hutt. 

 *Glycymeris laticostata (Q. & G.) 



Phalium fibratum Marsh. & Murd. 

 Polinices huttoni Iher. 

 Terebra sp. 

 *Verconella mandarina (Duclos) 



Lucinida levifoliata Marsh. & Muxd. Verconella cf. nodosa (Mart.) 

 Miltha sp. *Spisula ordinaria (E. A. Smith) 



Ostrea sp. 



In addition to the above the writer saw, but did not collect, Voluta sp., 

 Flabellum sp., and plant-remains of various kinds. At one place worm- 

 casts such as are commonly called " fucoids " were exceedingly abundant. 



At the brickworks quarry, on the south side of the Patea River, near 

 the bridge leading to the town, Atrina sp. — perhaps A. zelandica (Gray) — 

 was collected. 



As already mentioned, the cliffs east of the Patea River were examined 

 by Hutton in 1884. He states that twenty-six species of Mollusca were 

 collected from the blue clays, of which 77 per cent, were Recent (3, p. 340). 

 His Wanganui lists mention the following twenty-five species, twenty of 

 which are Recent, as indicated by a prefixed asterisk : — 



