The Great Geoadvent: Door 7

This year’s geoadvent features some of our favourite entries from photography competitions past and present – all of which feature the beautiful geology of the UK and Ireland.

You can purchase a copy of this year’s calendar, featuring our 2018 competition winners, on our online bookshop, or by visiting us at Burlington House!

Door 7: Staffa

Staffa c. Louise Squire

This stunning image of Staffa was sent to us by Louise Squire, and featured on the cover of our very first Earth Science Week calendar in 2016.

Further info:

The island of Staffa is composed of columnar basalt and overlying ‘slaggy’ basalt, erupted as lava flows from the Palaeogene Mull volcanic centre.

The lava flows on the island were erupted early in the history of the Mull volcanic centre, which forms part of the North Atlantic Palaeogene Igneous Province, along with the other centres of Skye, Arran, Ardnamurchan, Rum and St. Kilda.. The columnar jointing, commonly found in these flows is typical of the early lava flows only.

The presence of ash layers and thin soil horizons indicate explosive activity and intervening quiet periods respectively.

The composition of these lava flows also differs from the later flows by being the most silica-rich flows – thought to have formed due to shallower accumulations of the magma before eruption. These flows are known as the Staffa Magma Type member and are also seen at Carsaig, Ardtun, Ulva and near Tobermory.

‘Fingal’s Cave’ on the Isle of Staffa is internationally famous, having been the inspiration for musicians, artists, poets and writers for many years, most notably for Mendelssohn’s ‘Hebridean Overture’.

The island and cave was brought to the attention of the scientific world by Sir Joseph Banks (1743 – 1820) who was on route to Iceland on a natural history trip. In his writings he compares the island’s appearances to lava, and it should be noted that this came before Hutton’s ‘Theory of the Earth’.

Text: Scottish Geology

Images:

Basalt Columns and later lava flows above © Hugh Venables (Source Geograph.org.uk) Creative Commons Attribution-ShareAlike 2.0 license.
Columnar Jointing in early lava flows © Hartmut Josi Bennöhr (Source Wikimedia Commons) Creative Commons Attribution-Share Alike 3.0 Unported