Geoverse

I’ve been pretty busy up to now. Thankfully we have a 4 day easter weekend coming up. I intended to go to Sydney but there is an Easter party on Sunday and on monday I may get a double bed from a graduated and departing PhD student. She has been accepted as a post-doc fellow at Oxford! And I wanted to work some more on my website / make a new one so friday and saturday would be good for that. I still need to do some sightseeing in Canberra anyways as well. My house mates will be off to check up with their folks. But that’s not what this post is about. 🙂

I’ve been doing a lot of SEM work lately and yesterday I had my first session operating the Cambidge SEM apparatus. The samples we are using right now are not mine but they are useful because mine will be similar to them. Oxidation of the iron bearing olivine samples, that have been pre-deformed, allow me to image
dislocation lines (as well as grain boundaries) with BSE (electron
backscatter) using the SEM (scanning electron microscope). Oxidation will
increase the average atomic number at edges, dislocations and grain boundaries
increasing the frequency of backscattered events and consequently these areas
show up with a bright contrast. The advantage of using the SEM over the TEM
(transmission electron microscope) is that lower resolutions can be taken to
increase the scanning area and improve upon more representative unbiased
dislocation density measurements. Also sample preparation is much faster for
the SEM than for the TEM. A 10 -12 minute alumina polish (grain size ~0.05μm)
removed most of the oxidized coating on the sample but did not remove the
oxidized dislocations themselves. BSE imaging was done at 20kV and 500pA.
I’ll be trying lower voltages at 5, 10 and 15kV as well. A lower voltage is
preferred because it will reduce the imaging depth of field (DOF) and decrease
the 3rd dimensional component which causes blurs to be visible of features underneath the surface in the
2-dimensional SEM image. The downside is
that because the sample contains atoms of a higher atomic number (Si, Fe, Mg…),
a too low voltage will not force powerful enough elastic collisions with the
atoms and the backscattered electrons will be in a diminished concentration and
consequently only very low contrast images will be obtained. Low contrast images
may or may not be useful. That’s what I’ll be determining on next Wednesday when I’ll be using the ‘new’ Hitachi 4300 SE/N SEM apparatus rather than the 15 year old Cambridge one. The Hitachi supposedly handles lower acceleration voltages better.

Anyway, there ya go. 🙂 Once I sort out the best method of obtaining SEM images of dislocations in olivine and how to best estimate the dislocation density in the olivine samples I’ll be focusing my attention to torsinal forces oscillation experiments, dislocation annealing and hot pressing.

On Saturday, 25 March 2007, at 8:30
am we set off with 3 cars packed with people for a 100 km drive to Deua National
Park to see the ‘big hole’ and the ‘marble arch’. The drive took a fair while and on our way we briefly stopped in
Captains Flat because one of us, Cheryl, was required to vote in the
NSW state for that days state elections. We had a good laugh when we set off
again and Cheryl’s car would not start so her passengers had to push the car a
fair bit until the engine came alive again. Not much further on Robert, with
whom I sat in the lead car, suddenly noticed a ‘walking rock’ in the bend of
the road. As he observed correctly, however, it was in fact a turtle larger
than the size of your hand! The others of the group soon joined in to watch it
and some took a couple of pictures of it. It was then safely put back on the
ground away from the road.

At last we arrived at Deua National
Park and started a promising bushwalk to see some
of nature’s incredible phenomena. It didn’t take long before we hit our first
obstacle, the Shaolhaven
River. Most people
managed to get across without getting wet, despite the rocks being very
slippery. For those with sneakers however, many opted to take their shoes off
and wade through the water.

From thereon it was a lovely and casual walk to the first
feature of the trip, the big hole. On our way we also spotted some wallabies
and some joeys.

The big hole is a morphological
feature properly known as a sink hole. It is over 100 metres deep. Before its
existence, there must have been a large cave underneath the surface that formed
in a thick limestone layer. The limestone was dissolved and carried away by
underground water probably to the Shaolhaven
River. At some point the
cave ceiling composed of siltstone, sandstone and conglomerate rocks must have
collapsed creating the big hole. These sedimentary rocks are about 350 Million
years old, deposited during the Devonian geological era in a coastal
environment.

We had a short break and then moved on to see the next
highlight of the trip, the Marble Arch. As we walked through the eucalypt
forest massive mounts of dirt were spotted between the trees. These are
presumably abandoned termite mounts. Since we didn’t see the termites
themselves it still leaves me wondering where they went. I had a picture taken
of me on top one of these big mounts.

We finally arrived at the Marble
Arch, which is a limestone cavern followed by a river gorge. We took out our
torches and headed into the cave. The name Marble arch is rather misleading because there is
no marble to be found, just limestone and limestone breccias.

The experience was awesome as we made our way through the
cave and the narrow gorge with cleanly polished rocks caused by the action of
the water over a long time. The rocks were extremely slippery too and it didn’t
take long before some of us lost balance and slit into the shallow pools of
water in the gorge. Although getting wet didn’t hurt, the main scare turned out
to be the leeches in the gorge. I managed to get a remarkable shot of one of
the bigger ones. We had lunch in the gorge where we couldn’t go any further
because of a small lake blocking our way. For some great group pictures with us
all having lunch, see the ANUMC website. That is, if they have been uploaded
already. After lunch we made our way back to the cars along the same path we came
and headed back to the SRA and got back by around 5:30 pm.

All in all, this trip was awesome!!
And I think everyone fully enjoyed themselves as well. Apart from a few wet
feet, nobody took the plunge or got hurt.

I have uploaded the rest of the photos in high res here for your viewing pleasure.

Tonight I have been playing ultimate for the first time. I’m surprised how popular the sport is here as professional players don’t actually get paid for playing. I found it good fun though and it’s something new which I like. The frisbee throwing techniques are far more complex than at first sight but I think I did pretty well. The backhand in front of your body is relatively easy but the forehand, like skipping a stone over the pond, requires some more skill and proper handling. The key is to give the disc enough spin so that it flies in a stable trajectory through the air. In two weeks the new season starts so i’ll be joining up with the RSES team (if there are enough players hopefully) and we’ll see how I will fare in the tournaments. In the meanwhile I need to practice, practice and practice 😛

Tomorrow i’m off for a hike in one of Canberra’s national parks with the mountaineering club. I’ll take some pics as well. The river gorge and the caves are said to be absolutely beautiful!

See ya!

I’m living in another country. But Australia does belong with the developed countries like the USA and countries in western Europe. So what exactly is different apart from the fact that the language spoken is different? Here are some differences i noticed between the Netherlands and Australia:

1) At the supermarket (no matter which one), you are greeted friendly and the cassiere even sorts out your shopping items in plastic bags for you. They also take your keycard (pinpas) and swipe it themselves for you.

2) Pin transactions are similar with a 4 digit pin code but you have the opportunity to select which account you want to use. That’s savings for me.

3) Always when waiting in line, wait until you are called. It’s ‘rude’ to step up when you think the person before you is done and walks away.

4) Cycling on the road is allowed but the roads are not build for cyclists. Cycling on the sidewalk where pedestrians walk is much more common and apparently also allowed. There are some bicycle tracks in Canberra. In Australia people drive on the left side of the road.

5) You must wear a bike helmet by law or face a fine up to $50

6) There are few custards (vla) and yoghurts and a smaller selection of brand cheeses or you have to pay a lot for little.

I’ll add some more things later on.