type Waitotaran, and the type Nukumaruan. The Kaawa beds are regarded as being Waitotaran or slightly older (Laws, 1936, p. 42). They differ from the type Waitotaran in station of deposition; the Kaawa beds were deposited near a shoreline in water not deeper than about 15 fathoms (Laws, 1936, p. 41); the beds of the type Waitotaran at Hawera, on the other hand, were laid down at a distance from a shoreline, and at depth ranging from 25 to 30 fathoms (Powell, 1931, p. 90). The fossils therefore indicate a Waitotaran or Nukumaruan age for the Kowhai series. On the evidence of the Miocene element in the fauna, together with the occurrence of Ostrea ingens, the Kowhai series is assigned to the Waitotaran stage. The fauna of the Kowhai series has more in common with that of the Kaawa beds than with that of the type Waitotaran. This feature is due to the deposition of the Kowhai series and the Kaawa beds in much shallower water than the beds of the type Waitotaran. The Kowhai series represents a shallower water facies than the Kaawa beds; it was laid down very close to a shoreline where the sediments were coarse and the currents strong—as witness the gritty or conglomeratic nature of the shell-beds, and the worn and rubbed surfaces of the fossils. The shallow water origin of the Kowhai series probably explains the resemblance of the fossils to those of the type Nukumaruan, which was laid down under very similar conditions. The determination of the Kowhai series as Waitotaran introduces difficulties when comparison is made with the account of the geology of the Middle Waipara-Weka Pass district by Thomson (1920). He distinguishes two series, lithologically similar to the Kowhai series, separated locally by an unconformity. The lower series, his Greta or Motunau beds, which he placed in the Waitotaran, contains a molluscan assemblage similar to that of the Kowhai series, as is shown by the list above. The upper series, which was unfossiliferous, he correlated with the Kowhai series of this area, at that time thought to be Pleistocene. The present investigation has shown that the Kowhai series as defined by Professor Speight is Waitotaran. From the faunal relationships it is reasonable to correlate the Kowhai series with the Greta Beds. Either Thomson's Kowhai series is a higher formation, in which case a new name for it is necessary, or the unconformity he described is intraformational and his Greta Beds and Kowhai series should be grouped together. The writer has not seen the locality where Thomson described the unconformity between his Greta Beds and Kowhai series, but evidence from other places favours the second explanation. Terrace Gravels. The gravels lying on the truncated surface of the Tertiary and Cretaceous rocks were deposited by the rivers traversing the area at various stages in their history. These river gravels are similar in lithology to the gravels of the Kowhai series, but the greywacke pebbles are not so well rounded and vary more in size than do the pebbles of the Kowhai series. Where contacts can be seen the terrace gravels can be easily differentiated from the Lower Pliocene gravels, but elsewhere, especially on the lower slopes of the downs around