Paleocene-Eocene (map symbol E)

Rocks of these ages are mapped together for cartographic convenience.

Paleocene rocks crop out in Marlborough, Canterbury, on the west coast of the South Island, east coast of the North Island, and in Northland. Eocene rocks follow a similar pattern, but are more widespread.

The rocks are mainly sedimentary, the few volcanic rocks being confined to north Otago.

Paleocene image

The Paleocene is represented by marine greensand, siliceous mudstone and chert, minor limestone, and sandstone in Northland, eastern North Island and eastern South Island. In south Westland, however, marine conglomerate, greensand, and limestone date from this time. The Eocene rocks are also dominantly of marine origin in the east of both islands: glauconitic sandstone is still common, while a distinctive white limestone is present in north Canterbury, Marlborough, and southern Wairarapa. Bentonitic mudstone is a characteristic deposit of areas in Wairarapa, Hawkes Bay, and some areas of Northland. An unusual deposit dating from the Eocene is the Oamaru Diatomite, a siliceous mudstone made up entirely of the hard parts of tiny marine organisms called diatoms. Basalt, pillow lava and tuff of Eocene age are also found in north Otago especially at Oamaru. The western and southern areas of the South Island and western areas of the North Island all contain non-marine deposits of Eocene age; many of these are seams of bituminous and sub-bituminous coal. Eocene deposits are widespread in the west of the North Island, but are concealed by younger rocks. Eocene coal measures are present at depth, and have been found in drillholes (e.g., Kapuni), from Taranaki north to the Waikato River. Coal measures near Whangarei in Northland date from the Late Eocene. In the Late Eocene, marine deposits of mudstone, greensand, and limestone are recorded from areas in the south of the South Island.

Paleogeographic conditions
At the end of the Cretaceous much of the mountainous land had been eroded to an almost-level plain, though the process continued well into the Eocene in western and southern districts.

The land mass was very low at this time and deeply weathered; coal measures were being deposited in the swampy, marginal coastal area. The Paleocene and Eocene saw a gradual invasion of the land by the sea, particularly in the east. By the Late Eocene only the western half of the North Island, and a belt of land with offshore islands further south, remained above sea level.

The tectonic conditions were generally quiet and original deformation is slight. Later movements in the Kaikoura Orogeny caused folding and faulting, in places severe, particularly on the east coast.