Bell Creek Area, Ardmore.
The valley in which Bell Creek flows heads south for a distance of about a mile from the junction of Ardmore Quarry Road and Papakura-Clevedon Road. Two points of contact between the older and younger formations were here located, the first in the bed of Bell Creek, about half a mile south of the junction mentioned, where a pocket-like lens of breccia-conglomerate rests on the irregular surface of the older rocks and is undoubtedly a shore-line deposit, possibly derived from an adjacent cliff in the ancient coast-line. A few inches above the basal conglomerate a discontinuous one-inch band, rich in foraminifera, lies just beneath a flaggy calcareous sandstone or arenacous limestone (Fig. 7, Plate 3) with thin bands of mudstone, which strikes S.6°W. and dips at 8° to the north-west. This last bed is current-bedded and contains abundant plates and spines of echino-
derms and tests of foraminifera, as well as brachiopods and algae it thickens downstream, where it includes water-worn pebbles of coal, due no doubt to the contemporaneous erosion of a seam elsewhere, for coal is found below the limestone at other localities in Hunua Range.
About a mile south of the previous contact, the basal conglomerate is admirably exposed on the right bank of Bell Creek, resting on a worn surface of greywacke (Fig. 2, Plate 1). It contains broken shells of oysters and other molluscs and a few brachiopods, and is overlain by at least 20 ft. of sandstone, with poorly-preserved marine fossils, which dips at 5° to the north-west. These exposures are 230 ft. above sea-level, so that the surface of the Mesozoic rocks rises here in a southerly direction, a fact of importance, for it throws light on the structure of the Papakura Valley depression to the north and will be referred to subsequently.
On the west side of the valley, several hundred yards due north of this second contact, beds of fairly pure limestone, apparently about 30 ft. thick, are exposed in two sinkholes now almost completely masked by a tangle of vegetation. Most of the rock has a crystalline
appearance owing to the abundance in it of echinodermal material in addition to other organic fragments; in some parts of it small gritty particles of greywacke are common.