The geological history of New Zealand
The beautiful country of New Zealand has always been a land of nature and a land of immense natural diversity. With its the glorious landscapes, stunning beaches, volcanoes and amazing mountains it has been impressing both travelers and geologists as well. There has always been a question – how was it created to be so beautiful.
Geological setting
Modern New Zealand is world renown for being geological active with high mountains, frequent earthquakes, geothermally active areas and volcanoes. This is due to New Zealand’s modern position on the boundary of the Australian and the Pacific Plates. The collision of these plates caused the Pacific plate to subduct underneath the Australian plate which carries the North Island. To the south of the South Island, the situation is reversed. The subduction zones in New Zealand are defined by trenches in the north and in the south and by the Alpine Fault which connects the two. This plate boundary has shaped the size of New Zealand and also defines its geology.Radiometric dating places the oldest rocks in New Zealand being at least 500 million years old.
New Zealand’s geological history can be divided into three main periods of sedimentation and three periods of mountain building (orogeny).[1]
The New Zealand region lies in the southwest of the Pacific Ocean astride a distinct belt of volcanic and earthquake activity that surrounds the Pacific Ocean. This is the Pacific Mobile Belt or “Ring of Fire” and the activity results from the structure of the Earth’s crust. Wherever there is a plate boundary there is geological activity of a volcanic or tectonic nature. [2]
History
New Zealand’s origin as part of Gondwana, the composition of its ancestral biota, its geographic isolation for 80 million years, its tectonic history of changing shorelines and mountain building, and its changing climate, have all influenced the composition and distribution of its plant and animal communities, and thus its ecology and evolutionary biology. Recent DNA-sequencing studies combined with palaeogeographic analysis suggest that an Oligocene marine transgression had a major genetic bottle-neck effect on the biota and, together with recent advances in avian biogeography and paleontology, are leading to new hypotheses on the origin of many bird groups.
[3]
Sea-floor spreading data from the Southwest Pacific have recently been used to predict the Cainozoic geological history along the Indo-Australian/Pacific plate boundary. Geologic and sedimentologic data pertaining to this plate boundary where it crosses southern New Zealand, as the Alpine Fault, are summarised and discussed. It is concluded that there is a close accord between the plate-tectonic predictions and South Island Cainozoic geological history. In particular, (1) no Cainozoic plate boundary traversed the New Zealand region prior to 38 m.y. B.P. (late Eocene); (2) transcurrent movement on the Alpine Fault took place largely between ca. 30 m.y. B.P. (middle Oligocene) and ca. 10 m.y. B.P. (late Miocene); and (3) the period 10 m.y. B.P. to present corresponds to a phase of oblique compression, continental collision, and mountain building along the Alpine Fault sector of the plate boundary. There is a close correlation between the sites and histories of Cainozoic sedimentation and this tectonic timetable.[4]
As is well known, the skeleton or oldermass of New Zealand is largely composed of a mass of deformed sedimentary rocks, the precise ages of the members of which are in doubt but do not affect the problem under consideration. The most profound deformation of this vast sedimentary group took place in late Jurassic or early Cretaceous times during what may be termed the “Mesozoic orogenic period”, when probably a great mountain range came into existence.[5]
Waitomo Caves: These world-renowned caves are home to the Waitomo glow worms, also known as Arachnocampa luminosa. These illuminating creatures are unique to New Zealand so you will not find them anywhere else in the world. This truly unique experience will allow you to take an expertly guided tour of the magnificent caves and marvel at this natural attraction’s historical and geological significance. Discover the majestic and natural decorations of the cave and see the limestone shaft and magnificent cathedral cavern in whole new light. [6]
Conclusion
With its complex geological features comes its very beauty. Each piece of New Zealand was chiseled to the perfection and all that thanks to its miscellaneous and manifold geology.
References:
[1] http://sci.waikato.ac.nz/evolution/geologicalHistory.shtml
[2] http://data.gns.cri.nz/geoatlas/text.jsp
[3] The New Zealand biota: Historical background and new research by Roger A. Cooper and Philip R. Millener
[4] Cainozoic history of southern New Zealand: An accord between geological observations and plate-tectonic predictions R.M. Carter and R.J. Norris
Department of Geology, Otago University, Dunedin New Zealand
[5] The Structure and Later Geological History of New Zealand by: C. A. Cotton
[6] http://www.discovery-motorhomes.co.nz/
