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Piercement structures, local unconformities, and secondary sedimentary basins observed in the Eastern Geosyncline are often closely associated with transcurrent fault-zones. Spasmodic and uneven transcurrent movement along these faultzones is thought to be responsible for the features, Their probable development is shown diagrammatically.

A structure in the young Tertiaries of the Patoka district, northern Hawke's Bay, is anomalous when the area is compared topographically with districts further north and south. A faulted body consisting of greywackes of probable Jurassic age, has, pushed the Tertiary and its lower Pleistocene cover up, and initiated the local anomalous topography. The action started in N ukumaruan time. The movement had a mild southern component causing, disturbance in the area immediately north of the Opau greywackes,

The Mesozoic and Tertiary strata of Hawke's Bay include many sequences of vertically graded, banded sediments, some of which are contemporaneous with sequences of massive sediments deposited in nearby localities. The distribution of the thickness of sediments in Central Hawke's Bay, indicates that a trough-like basin existed in the upper Miocene. Into this basin a thick sequence of banded' sediments was deposited, while at the same time a thin sequence of unstratified beds was laid down in the area surrounding the basin. An investiga-t10n of the grain sizes in the basin revealed a decrease in grain size in a westerly direction. The sediments were brought in from the east, presumably across a bar which is thought to have separated the basin from the open ocean.Kuenen and Migliorini's theory that graded sediments are deposited by turbidity currents cannot be applied satisfactorily. The banded sequences of the upper Miocene and their massive equivalents show that these beds must have developed by a different mechanism.Both the above mentioned basin and the bar subsided irregularly and intermittently, the basin subsiding' more than the bar. As a result, the relation between bar-depth and basin-depth varied continually. Consequently there were changes in the speed ,and strength of currents across the bar. Grain size and the amount of sediment carried into the basin by these currents changed rapidly, causing' bai\ded sediments with vertical grading. The deposition of sediment continued in this way until the incoming current lost its power to transport coarse material. With the gradually diminishing carrying capacity cf the incoming currents, increasingly finer sediments were brought in until current flow ccaseel almost cntirely and only muds were laid down. With subsequent down-\vard movement coarse material was 3.gain carried in. The system reflects an immediate lithologIcal response to tectonic movement.

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