How do we examine climate change in the past? In this article Professor Nicky Milner discusses the work at Star Carr
Sediments can also tell us a great deal about the environment and climate change. Although as scientists we have a general record of climate change from records like the Greenland ice cores, it is essential to have a detailed understanding of records from nearby sites which tells us about the regional changes. For humans living in these areas at the time it is the local environment that matters and as archaeologists we are interested in knowing whether people responded to these local changes in climate and environment.
At Star Carr we were lucky enough to work with an expert team of climate and environmental scientists
based at Royal Holloway and the University of Southampton. They used a range of drilling equipment to extract cores from metres of peat in what would have been the lake near to Star Carr.
This is an additional video, hosted on YouTube.
In the core in the video a number of different layers are discernible: wood peat at the top, which is brown in colour with inclusions of lighter brown branches and twigs; reed peat directly below this, which is darker and greener in colour, finer in texture, and with frequent plant and seed inclusions; then transitional muds rich in organics (gyttja) marking the bottom of the lake; and finally transitioning into a marl sequence which ranged from dark to light green in colour. The marl is alkaline while the peat above now highly acidic. Depending on where the core comes from across the site and the depth to which the core is taken, it is typical to contact glacial till, a mixed orange/brown sand/gravel, and also grey/buff coloured clay.
Within these sediments they were able to extract a range of data from plant remains, pollen, chironomids (non-biting midges), oxygen and carbon isotopes, and tephra (volcanic ash) which they used to reconstruct the climate and environmental record over time. From this analysis it was shown that an abrupt climate event occurred at Star Carr during the early part of the occupation.
To find out more about how the lake was cored, see Chapter 18
. An explanation of what would have happened through time to the lake and the environment is provided in Chapter 4