Thursday 20 March 2014

Meteorites!

This week has been Science and Engineering Week at Plymouth Museum, and there have been several stands in the museum with different activities related to disasters that cause extinctions. On Tuesday, Wednesday and Thursday groups of school children aged 4-11 came to the museum to learn about these disaster, and on Friday and Saturday it is going to be open to the public. I have been helping out on a stand looking at what might have caused the dinosaurs to die out, concentrating specifically on meteorites.

The activity was split into three sections. The first section was an introduction into what dinosaurs and meteorites are, to make sure that all of the children had a similar level of knowledge about the subject. We explained that there a three types of meteorite - iron, stone and stoney iron, and that they all are magnetic due to the iron within them.

The second section involved us explaining what impact craters are, and that there are two types - simple and complex, before doing an experiment, where the kids could make their own craters. This involved dropping a ball into a box filled with black beans, then couscous, then sand mixed with flour - this was to help show different layers within the Earth. We had two boxes and two balls - a heavy one to represent a heavier iron meteorite, and a light one to represent a lighter stone meteorite. Two of the children from each group dropped the balls into the sand boxes, and we then took them out and looked at the craters that they left behind. The heavier ball created a larger crater, showing the different layers, and the lighter ball created a smaller crater, which barely dented the sand/flour mix. The photo below shows one of the larger craters which was made by the larger ball.


Big crater, complete with dinos!
For the final section we explained how scientists relate meteorites to extinctions, and how there may be other causes such as massive volcanic eruptions called flood basalts. We then had a box of rocks, some of which were meteorites and some of which weren't, and we let the children determine which were which. They did this by using a magnet to pick out the magnetic rocks, which were more likely to be meteorites. If there was time they also filled out a worksheet, which involved summarising the three types of meteorites, drawing an impact crater (or a dinosaur for the younger children) and explaining what scientists think killed the dinosaurs. Below are a couple of my favourite pictures - apologies for the bad quality of the pics, and that two of them are upside down!

Very good answers!

Groovy dinosaur!

Meteorite, crater and volcano!
All of the children seemed to have a lot of fun, and I really enjoyed helping out with the activity, and I hope to do something like this again.

Sunday 9 March 2014

Palynology

I'm still here! Apologies for the lack of blogging recently, I've been rather busy!

On Thursday and Friday I went to Exeter University to have a practice run of the palynology work that I will be doing with my samples. Palynology is the study of the fine grained particles and dust in sedimentary rocks. I was doing a palynofacies analysis, which involves looking at acid resistant organic matter, such as pollen and spores. This organic matter is obtained via adding hydrochloric acid and hydrofluoric acid to the samples to remove the carbonate and silicate minerals. The material that is left behind is then placed on a microscope slide to be analysed.

I looked at some samples from one of the studies by one of the lecturers, and I counted each of the different types of organic matter. These included spores, pollen, plant tissue, marine microfossils and black debris. I tallied these up in order to get some indication of the nature of deposition of the sediment. A large amount of spores, pollen and plant tissue would indicate a terrestrial deposit, a large amount of marine microfossils would indicate a marine deposit and a large amount of black debris would indicate a coal deposit. In this study, most of the samples were terrestrial with a lot of pollen, spores and plant tissue, and one of them was a coal deposit, having a large amount of black debris.

This study was a training exercise, to give me an idea of what I will be doing when my samples have been processed, so hopefully I'll be doing this again very soon. I shall end this post with a few pictures of the organic matter that I saw - the scale bar at the bottom of each one is 20 micrometres, or 0.02mm.

Plant Cuticle

Degraded Plant Tissue

Bisaccate Pollen

Plant Tracheid

Black Debris

Trilete Spore

Plant Tissue