Rock samples from Antarctica, collected by Captain Falcon Scott and his team during the British Antarctic Expedition otherwise known as the Terra Nova Expedition (1910 – 1913), are among the treasures of the Natural History Museum Petrology collection. A CT scan tells the story of a land, once warmer and rich in vegetation rather than the frozen and inhospitable Antarctica we know today.
Read on to learn about this rock in our collections, and the story it tells about this lost world.
What is it?
The specimen pictured below is a sandstone; a sedimentary rock composed mainly of sand-sized mineral particles. It is mainly made of minerals such as quartz, and feldspar mineral fragments but it also has layers of Iron-Titanium rich grains and plant remains.
How did it form?
This rock formed, by the settling of loose mineral or organic particles to the bottom of a body of water, possibly a lake, and subsequently hardening into a rock. These processes are known in geological terms as sedimentation and diagenesis.
Where is it from?
The sample was collected at the Priestley Glacier moraine, in Antarctica during the expedition led by Captain Falcon Scott, known as The Terra Nova Expedition. The expedition had various scientific objectives, and carrying out geological studies of Antarctica was one of the aims of the mission.
Unfortunately, Scott and his team died on the return journey from the South Pole; some of their bodies, specimens collected, photographs etc. were recovered by a search party several months later. The specimen being discussed in this blog is one of the many samples collected during this expedition and then donated to the Natural History Museum.
How are we studying it?
We used CT (Computed Tomography) technique to create 3D models of the internal and external features of specimens, this is a non-invasive and non-destructive technique that uses X-rays irradiating the specimen as it rotates 360°. This technique allows us to look inside the rock without cutting it open.
In the movie above, you can see the plants remains embedded in the sandstone and the little metal grains showing the orientation of the bedding.
We also used one of our Scanning Electron Microscopes (SEMs). This microscope produces images of a sample by scanning the surface with a focused beam of electrons. Below we can see the SEM images of the plant remains found in the sandstone.
The microscope also measures the energy released as the electrons hit the sample and this allows us to investigate the sample’s composition and produce a map of the element distribution on the rock surface. The image below, for instance, is a close up of some of the metal grains found in the sandstone that can also be seen in the 3D reconstruction movie.
Why are they important?
The rocks and fossils collected during this expedition have a great historical and scientific importance. They are historically significant because of their association with Scott’s ill-fated Antarctic expedition.
They also showed that through time, rocks deposited in warmer areas had moved over the surface of the earth. These findings later paved the way for the plate tectonic theory to be proven playing a crucial role in changing our geological understanding of the planet. These specimens also show that Antarctica was part of an ancient supercontinent called Gondwana, and used to have a much warmer climate that allowed the growth of trees.
If you would like to see some of these fascinating historical samples from this lost world now called Antarctica, you can visit the Natural History Museum Terranova Expedition balcony display in the Hintze Hall, or if you want to have a closer look at these rocks, do get in touch with the Petrology curator.