Category Archives: Uncategorized

Waipara gorge

Last Friday, Nicola and I went with Catherine Reid to look at some areas of the Waipara river, where Nicola’s school does a field trip. This was an opportunity for us to have a look at some of the geology of the area so that we would be able to explain it to our kids at school.

DSC_1008 The flat parts under the forest have been formed by the debris coming down the river at a time in the past, which has been deposited and built up the landscape. This has later been cut through by the river (when it has less debris coming down from the mountains) exposing the layers and cutting out the gorge.DSC_1009

The earliest rocks have been tilted by plate movement causing the different angles.

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The angles are noticeable in this unconformity. The lower (older) rocks are tilted. On top of them the river has deposited new layers of material, and then as its sources of material have diminished it has cut back down through all the layers exposing this unconformity.

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These are old sandstones again and are on an angle. In them are fossils, and some examples of concretions.

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This is a concretion. It is part of the sandstone that has become much harder than the surrounding rock because of the precipitation of minerals that hold the pieces of the rock together.

Concretions are usually mostly spherical in shape and can be seen all through the river as boulders that have been washed out of the sides of the river.

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These are some from in the river.

They also have trace fossils in them. These are areas where something has been before it hardened and have left marks which then hardened with the stone.

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We also found fossils in the sediment walls of the gorge.

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We spent too long looking at stuff in the part of the river we were in so we didn’t make it as far as we were supposed to last week, so hopefully (if the weather clears!) we will be going up to look at the rest tomorrow.

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Castle Hill Basin field trip

Yesterday I went along with my (well they will be my class when I am back at school anyway) Earth and Space Science class on their field trip to the Castle Hill area. This was done with the help of a Masters student from the geology department who was extremely useful and explained things really well to the class.

Unfortunately it was very cloudy at the top of Porters Pass so we could not see the fault there, but the weather improved down the other side and we were able to see some examples of the rocks that make up the area.

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We started at Castle Hill, checking out the limestone formations there. These limestone formations appear to dominate the landscape, but there is actually very little limestone compared to the older Torlesse rocks (sandstone, mudstone, greywacke). The limestone formed on top of the older basement Torlesse rocks when they were submerged by a large, shallow inland sea, which was inhabited by many shell forming organisms. These left behind the calcium carbonate shells that formed the limestone.

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Our second stop was in the Cave Stream area, where we looked at how the cave formed from the stream eroding of the limestone.

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The old stream bed is clearly visible here, where the path runs now. The cave entrance is just to the right of this photo. You can see how the stream eroded a path through here, before finding an easier route through the cave it eroded.

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The current stream, and some boulders of greywacke from the Torlesse rocks, against the limestone of the cave. The greywacke is much tougher and will erode less. As the rocks get further downstream they get smoother and rounder as they are tumbled in the water.

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In the cave stream area there are lots of lovely exposed faces cut by the river channels that geologists can use to see what has happened to the rocks by the angles they are all on, and also what is in each layer of rock. In the background you can also see the smooth flat planes caused by glaciation.

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Our final stop was Lake Pearson. Here we were looking at evidence of glaciation and postglacial erosion. The points where glaciers stopped is generally marked by a moraine, a ridge of sediment that has been pushed in front of a glacier as it advances.

When the glaciers melt, the water is left behind in depressions created by large chunks of ice. The melting also brings large amounts of sediment down, leveling out valley floors.

The erosion is always continuing, and Lake Pearson is very nearly divided in two by debris fans from the mountains either side.

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It was as exceptionally beautiful day down at the lake.

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Leadership Assignment 1

I have been very quiet on the blog front recently because I have been busy writing my first leadership assignment not doing exciting science things I could take photos of. All my recent photos have involved piles of books and post-it notes.

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This has been my life for the last couple of weeks.

I was a bit rusty on the essay writing but I have to say that it got easier as I went along. I actually enjoyed writing about leadership and I have found myself very interested in reading about it. It will have to be something that I try to keep up when I go back to school.

I have taken the opportunity to enjoy the lovely autumn weather we were having as well (until today) and did some of my reading on the deck with a view of the trees and sheep.

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This

Picking Forams

This morning I was finally able to get into helping do some lab work for my project. When we were in Brooklands, we took a core sample and Emma has been sorting samples from it and drying them. Now it is time to go through each section of the sample and look for forams.

Picking forams involves taking some of the sample and spreading it out on a tray then looking at it through a microscope and using a wet paintbrush to pick up forams and put them on a slide.

IMG_2572My tools.

Luckily I am pretty comfortable with a paintbrush, but once I was looking at it under the microscope I realised why I can never paint a straight line… My hand wouldn’t stop moving!

It was almost impossible to pick up a foram without grabbling bits of sand too.

My job was also made more difficult by the fact that I wasn’t very good at spreading out the sand on my try and so I didn’t have a nice thin layer.

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The sand isn’t supposed to be this thick!

There were very few forams in my sample, but it turned out that the ones that were there were very easy to spot. They were bigger than the sand grains and were nice and smooth looking so they stood out.

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This was a foram I found and put on the slide ready to be sorted.

On the slide there is a gel stuff that is used to thicken icing, but it dries on the slide, then when you use the damp paintbrush with a foram on it, it will make the foram stick to the slide. The good thing about this is that when you need to sort the forams into types, you can use a damp paintbrush again to move them around on the slide.

It was really interesting working with the post-grad students this morning and listening to the questions they asked, as well as the answers. It made me think that maybe part of the nature of science is the questions we ask and constantly asking why? It was also very clear that it is important to be methodical and make sure everything is very clearly labeled.

By the time I had done two hours of picking this morning, I had not even finished one sample. But I was starting to feel slightly nauseated from moving the try around under the microscope and bending my neck to look through it. I am definitely not used to using a microscope!

Last week

Well I have been rather quiet on the blog front for the last week or so. This has not been because I have not been busy, quite the opposite really. Last week we (the B(est) team) spent the week in Dunedin for our leadership course. This was a really fabulous time, and very thought-provoking. Or brain-hurty as we regularly described it. I have returned full of new enthusiasm for leadership positions and for some reason can’t wait to get started on my first leadership assignment. Im sure the feeling will pass when I start having to actually write an essay.

One of the really important parts of the course was having to work out what our values are. I realised that I have spent far too long in cadets because it is hard to go past Discipline, Respect, Integrity, and Loyalty. But then I thought more about it, and realised that the reason I am struggling to get past these is because they are essentially what I think I was taught from a young age (if not, sorry Mum and Dad but that is what I got out of all those times I was told to “mind your manners” 🙂 ).

I found it quite difficult when we had to stand up in front of every one and speak about a leader we admired. It turned out that none of us liked public speaking. But I did it and will hopefully be more confident next time I have to do it.

The leader I chose to speak about was Admiral William McRaven, not because I know anything about his leadership (although I can assume he must have leader someone well to be an Admiral), but because I was recently shown a video of him speaking and found it inspirational. It is a reminded that anyone can do anything if they want to. We have to start, take small steps, not be afraid, and not ever give up.

I think this is good advice for all of us, and sometimes you just need a little inspiration and the self belief that comes with it.

As part of the course we were also taken on a lovely tour of Dunedin. In classic Jags. 🙂

IMG_2534This was them parked outside the railway station.

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We went to a lookout.

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And attempted Baldwin St.

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And saw the first church. Looking lovely and gothic as it got dimmer.

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And had an amazing dinner in St Clair, at Starfish. In fact the food the whole time was amazing.

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Andrea and I posing with the car… I sat in the seat that the Queen had sat in. I practiced my wave the whole way through Dunedin.

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One lunch time I went for a quick walk and had a look at the geology museum at Otago and found these:

IMG_2515I’m quite familiar with forams now!

Rocks and a flume

Yesterday I went to a 200 level lab for the Depositional Envrionments and Stratigraphy (GEOL243) course. I had been to a lecture on Wednesday as was surprised to find that I actually understood what they were talking about. It turns out that a knowledge of the physics of waves was quite useful.

The lab started with looking at a variety of different rocks and they had to decide what processes had caused the sediment layers to look the way they did. They also had to decide if you could tell which way was up. A lot of this seemed like common sense to me, for example if a layer was eroded away and had another layer deposited in it then of course you could tell which was was up as erosion like that will always go downwards… yay for gravity. You can see an example of this in the second picture.

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The third picture shows a rock where the layers have been disturbed by something burrowing through it.

Some of the rocks contained trace fossils. These were also useful in helping decide which way was up.

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The second part of the lab was going to the flume to see sediment patterns being formed. When ripples are created in a current the sediment is picked up from the upstream side and deposited on the downstream side creating patterns.

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You can see the ripples created by the flow of the water.

IMG_2506The flume with the water flowing. Up close you could see the sediment being picked up and deposited further down.

This reminded me of being at the beach as a kid and looking at the ripples forming in the shallow water and watching the sand get picked up each time a wave went over. It was quite fascinating.

Core and Forams

This morning Matt Easterbrook showed Nicky and I the work he is doing on a core from the Avon Heathcote estuary.

First we had a look at some forams he has collected through the microscope. There are lots of tiny forams in each of the black squares on each of the slides.

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I tried taking photos of what we could see through the microscope, and it worked better than I expected.

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This is one square, and one foram.

He also showed us how the start to separate the forams from the sample, by using liquids of a particular density so that only the forams (and a few other bits) float. This is then decanted through filter paper and the rest of the liquid filtered off.

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The liquid is about $1000 per litre, so it is separated out and used again, and any that has been diluted has its water evaporated off and is also used again.

We also had a look at sand under the microscope, which is very cool! It is very rough, and you can see it is made from a wide variety of stuff.

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