Thursday, 25 April 2013

Borehole drilling continues!

This week I have been up in the Scottish Borders at the borehole site, it has been very exciting to see it all in action!
The progress to date is that we have passed the 100 metre mark. There have been some problems recently with fractures within sandstone units, which has delayed drilling while they have been in filled. Another issue has been that the hardness of the cementstones in the Ballagan Formation means that we need to use an especially tough drill bit. Due to the expertise of the drillers from Drillcorp we are overcoming these problems and drilling continues.
Geology problem solving 1: solving the problem of fractures in the rock by grouting the borehole with a cement-based mixture.
Geology problem solving 2: using a harder drill bit to cut through cementstones.  
I examined the core and was surprised to find that you can identify the rock type through the plastic core liner, and even touch to rock to check grain size through the slit in the liner. The quality of the core that we have extracted so far is excellent! Dave Millward, Mike Browne and Tim Kearsey are logging the cores on site as they come out of the borehole. This gives us a provisional record and a good indication of where we are stratigraphically (the relative age of rock units).
An example of the core in its liner, you can see the different rock units due to their colour variation
  There has been a lot of interest in the borehole, both nationally (see 8th April 2013 post ‘borehole drilling has started!’) and locally. Farmer and landowner of the borehole site Alistair Birkett has had many exciting discussions with the locals about palaeontology and evolution, while explaining why we are drilling the borehole. Thank you Alistair for making all this possible!
Landowner Alistair Birkett (centre) on site with me and Dave Millward
  Also this week, Tim and I visited our autumn field locality again, to look at some palaeosols and cementstones in more detail and do a little more sampling. It was fantastic to experience some fieldwork in the sunshine, and I had a happy reunion with the Geology Cat who was still there playing on the beach!
Until next time

Wednesday, 24 April 2013

Volunteers Week

Last week I was lucky enough to have two volunteers working with me for the entire week!

We had a busy week processing samples for microfossils. We sieved rock pieces through different sized sieves, dried the residues, and examined them under a binocular microscope. We picked out any fossils present and identified plant fragments, charcoal, fish and bone fragments. By noting the number of fossils present per gram of sediment sieved we are able to quantify the different fossil components and thus find out more information about the animal and plants that were present at that particular time.

The volunteers and I picking microfossils, with Tom Worthington (left) and Deborah Fish (right). See my blog post from 24th September 2012 ‘from mud to microfossils’ for more details.

Volunteer Deborah Fish using the SEM to examine microfossils, see my post from 3rd April 2013 ‘how science works: the scanning electron microscope’ for more details.

I really enjoyed the getting some extra help (more samples done!) and training up the students in micropalaeontology research methods. The next volunteers week will be this summer. Any students looking for microfossil or sedimentology research work experience do contact me!

Until next time

Friday, 12 April 2013

Borehole drilling video!

Borehole drilling has been progressing steadily. Yesterday evening the drillers had reached a depth of 70 metres. A thick sequence of sandstone underlies the surface, and we are now drilling into siltstones, mudstones and cementstones.

In the video below you can see the drillers changing over the core barrel after it has drilled out a core of sediment that is 3 metres long. A new core barrel is then attached and drilling of the next core continues. 

In the photo below you can see the core in boxes once it has come out of the core barrel. Each box is 1.5 metres long, and contains a core of rock, with the exact depth it came from recorded. On site the team record the rock type of the core and note any changes in its properties. The core is encased in a thin plastic liner during drilling to stop the core expanding due to pressure release. Once we have finished coring we will examine the properties of the rock in situ down the hole by using petrophysics (rock physics) techniques – I will explain what these are in a future post.

I am looking forward to examining the core on site when I visit in two weeks’ time.

Keep following for further updates on the drilling!

Until next time