First usage of the stratigraphic term Te Kuiti is reviewed, with special considerationof restrictions in its use and of the upper limit of its application. Adoption of the name "Te Kuiti Group" is supported, and a revised definition proposed. Stratigraphical, columns are presented covering an area from Papakura to Taumarunui. The constituent formations of the group are described, their type localities are recorded, and the following new formations are introduced:
The off-shore region between Mt Egmont and the Kaipara Harbour entrance forms the off-shore portion of the Egmont-Kaipara Sand System. The late post-glacial input of sand from landward sources into this system is less than 7% of the volume of post-glacial dunes which forms its coastal deposits. The only other source for the dune sand is the sea floor. Hence it is not surprising that the mineralogy of the sea floor and dune sands is the same. Furthermore, five separate periods of progradation are recognised that are correlated with five periods of sea-level fluctuations which have occurred during the post-glacial fall in sea-level from a local maximum of +2·1 m, 4425 years ago. The volume of progradation is approximately proportional to the net fall in sea level during each fluctuation. Departures from this proportionality are due mainly to insufficient time for equilibrium to be established between sea floor and new sea level. Sea level is currently rising and is promoting deposition on the sea floor down to depths of 50 m, beyond which there is a belt of coarser sand down to an average of 100 m. The main movement of sand is between the depth of 50 m and the shore. A wedge of sand from this region with a maximum, near-shore thickness of 2· 1 m (the overall post-glacial fall in the sea level) equals slightly more than the total volume of post-glacial dune sand preserved within the EgmontKaipara Sand System. It is concluded that the present sea floor is in partial equilibrium with sea level, and the local profile of equilibrium probably extends to depths of between 80 and 120 m.
Deposition of the Hinuera Formation in the south Auckland district began during the Last Glaciation. There were two main periods of sedimentation which culminated during two cool periods-one slightly more than 20,000 years ago and the other at some time between 12,000 and 16,000 years ago.The slopes on the surface of the Hinuera Formation are much steeper than the present graded reaches of the Waikato River and steeper than the surface on the Taupo Pumice Alluvium. The steeper Hinuera stages were due partly to increased rates of erosion and, possibly, partly to increased volcanic activity during-the cool climates. Periods of increased volcanism could have resulted from reduction of hydrostatic pressure during low sea levels. Log-log graphs of the surface profiles are useful in emphasising changes in slope.An appendix describes observations of an experimentally built alluvial fan, which led to several conclusions, including the following: When the load being transported by a stream is reduced, erosion starts and subsidiary fans are built out of the material eroded from the primary fan. At the same time terraces are cut upstream of the head of the subsidiary fan; these may be matching or non-matching, depending on the presence or absence of variations in load during their formation.A hill you may say is a hill; take a hill, Or a group of them forming an island, Range, or peninsula. Here's the benign Slope, thrust of deceptive hand Green-gloved over the strong racked bones Of earth assaulting sky. Follow the up, The flow, the fi'rnal burst in the sun; Measure the cone'; a' hill, you perceive, is a hill.
Four coastal deposits are recognised: two intertidal and/or supratidal-calm:weather and stormy-weather beach breccia and conglomerate; and two subtidal-back-reef breccia and biohermal reef rock. High-level outcrops of the subtidal facies provide evidence for six second-order transgressions of Late Holocene age. Most of these have been radiocarbon dated from Tridacna shells. Where Tridacna samples were available instead, all coral dates were rejected because of secondary aragonite contamination. The ages of the second-order transgressions correlate well with transgressions recorded from New Zealand and fall on a curve representing the first-order Flandrian Transgression and subsequent regression which in these islands reached a maximum of about +2'4 m 2760 radiocarbon years B.P. This maximum is about 1250 years younger than the +2'1 m maximum recorded for the northern part of New Zealand, and thus fits a predicted difference in timing of the Flandrian Transgression maxima caused by oceanic salinity changes. The net fall in sea level of 2'4 m from the Flandrian Transgression maximum has been of major importance in the development of atoll islets, which, mainly, if not wholly, as a result of this fall, have been built from sand taken from the shallow margins of the lagoonal floor. It may be no coincidence that the earliest Micronesian and Polynesian settlements date from about the period of the transgression maximum.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.