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Wednesday, 10 August 2011

Te Mata Peak

Last week, following my visit to Castlepoint I also headed further north to Hawkes Bay. State Highway 2 runs parallel to the central North Island mountain ranges, which had just received fresh snow from a recent southerly blast, to provide a classic New Zealand pastoral scene...
Te Mata Peak near Havelock North is a popular spot for runners, hikers and paragliders. On a clear day there are  spectacular views across the landscape from the coast all the way to the volcanic peaks of Ruapehu in the centre of the North Island.

The buttresses of Te Mata Peak are made of Awapapa Limestone. This formation, which is about three and a half million years old, is also found to underly other nearby coastal hills in the Hawkes Bay area. It was formed along a string of offshore shallow water shoals and tidal banks. At that time the coastline was about 40 kilometres to the west, along the present edge of the central mountain ranges. In between, the sediments of the same age are mudstones that represent much deeper water than the Awapapa limestone.



Armed with my Kiwi Fossil Hunter's Guide, I located a way to climb down on the eastern side of the peak to have a close up look at the cliff section just north of a radio mast, a few hundred metres down from the summit car park.

 Although there isn't a wide variety of fossils in these rocks, there were some vary well preserved specimens such as these examples of a scallop called Phialopecten marwicki, as well as barnacles, oysters, brachiopods (lamp shells) and coral-like bryozoans.

In places, thinly bedded layers of shell fragments
show that water currents were strong, indicating shallow water conditions when the limestone was deposited.










Careful research by scientists has found that the alternating bands of hard, strongly cemented grey limestone and softer, orange sandy layers represent cycles of sea level change during the Pliocene Epoch.

The harder layers formed because at shallower depths there were more water currents, which allowed more calcium carbonate rich water to flow through the sediments. This would have been during the ice ages, when huge amounts of sea water were locked up in polar ice caps, thus lowering the sea level.

The warm period (interglacial) deposits have less carbonate cement to strengthen them and are therefore etched out more easily by erosion. These deeper water sediments are now underneath overhangs of the harder layers. The example here had clusters of large oyster shells scattered within it.



10 comments:

Pauline said...

Hi Julian, when I lived in Hawkes Bay - many years ago, we used to go walking/clambering over Te Mata peak and often picked up shells and fossilised bits and pieces. I always had such a sense of awe about that - here we were on the highest part of Hawkes Bay, and there was this stuff that ought to be under water.... [you can tell I had no geological education at that time in my life!] Great blog, will keep an eye on your doings! Pauline

Anonymous said...

its hawkEs bay - not hawks.
It has an E in it.

Suzanne Rosvall said...

Thanks Julian for this post. Found info very helpful for online geology course presently doing.

Ed Snack said...

Note that there is an actual significant cave, current status unknown though. It is just below the new car park at the gates to the park and on the land that is proposed for purchase. When I visited some years ago there was the remains of an old car partially blocking entrance, but below that was a crouching entrance to a small chamber with a reasonable crawl of a couple of meters to a further small chamber. Beyond that was a further crawlway that was not explored.

I cannot find any evidence of exploration or a map from any source.

Anonymous said...

During school my year 10 science class had partipated in collecting fossels at Te Mata peak to see if we could have an inside look of the past. we had found bryozoan, oysters and much more. Some even got the opportunity to look at the bryozoan through a microscope at school which was really interesting to look at.

Anonymous said...

Recently my year 10 class took a trip to temata peek to look at the fossilisation and to see if we can look back at the history. We found a number of different types of shells and found out that we are able to tell the climate those rocks were formed and in some cases when they were formed. The rock also has some micro fossils in it that you can only see under a microscope. That is interesting!!!!!

Anonymous said...

In my science class, we have been learning about Geology. So we went on a trip to Te Mata Peak, to gather some rocks and build our knowledge. On the trip, we explored the different type of layers and fossils/shells that were cemented into the rock. When we go back to school, we explored the rocks and what we found more in depth. Overall the trip to Te Mata Peak was quite interesting. By going on the trip my knowledge of Te Mata Peak has become more broad.

Anonymous said...

For a class trip we went to Te Mata Peak for a geology trip, we walked a few on the different tracks to find and explore different things that Te Mata Peak is made up of. We found oysters and Bryozoan also limestone and many more things around Te Mata Peak. We brought some back to look under the microscope which was really interesting to see it from a different view and to see the different things in the fossils.

Anonymous said...

In my year 10 class, we took a trip to Te Mata Peak, since we have been learning about geology and about the past. We found lots of different fossils and shells and things like limestone, oysters and more. We took a photo of the class at the top of Te Mata to remember the trip. When we got back to school we started doing reports about Te Mata and some people brought some limestone back to look at it under the microscope which was really cool. It was a nice class trip.

Anonymous said...

For one of my classes trips we went to Te Mata Peak for a geology trip we walked around and looked for fossils and different types of layers. We found oysters and bryozoan also limestone and many more things around Te mata peak. We brought some back to look under the microscope which was really interesting to see it from a different view. This link is some of the fossils I picked out of the rocks with tweezers.

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