Saturday, November 24, 2012

Discovery of Devonian rocks

Flag of Devon county
auxilio divino By divine help

Devon (6,707 km2)
Devon is located in the South-Western corner of British isles. The name derives from celtic tribes living there already in the Iron Age. The Romans called  them Dumnonii from the celtic word dubnos, deep, and thus "those who live in deep valleys". * 

Today Devon county has about 1,140,000 English inhabitants.  The capital is Exeter (119,600) located near the Exe-river. West from Devon is Cornwall and in the East are Somerset and Dorset.

According to geologists Devonin is divided by a clear line which is part of the large Tees/Exe line. East from the geological line are thick sedimentary rocks that create a soft landscape of plains, hills  and valleys. To the West from this line are volcanic and metamorphic rocks creating much rougher and erosion-resistant landscapes.

The Victorian era was remarkable time of geographical expeditions in the growing Empire, especially to Africa. It was also a time of mapping the geological and archaeological history of British Isles and explorers made notes of soil, rock, color and attributes of sediments, hardness and other geological features.

Sir Robert Murchison
The area of Torbay on the Canal coast of Devon was studied by two famed persons considered among the fathers of modern Geology. Scottish Baron Roderick Murchison (1792-1891) is credited for being the first to define Silurian. His friend, Adam Sedgwik (1785-1873), was the first one defining Devonian and Cambrian periods. The two were working especially in the Lummaton quarry where reddish sandstone mixed with limestone contains fossils.

In Devon County such geological sediments appear in North and in South-West where it continues also to regions in Cornwall. Later on similar deposits have been found in other parts of the world providing evidence what is today known as the Devonian age in the geological time age and often "Age of Fish" in the history of life on planet Earth.

The Lummaton quarry is apparently still today among the most significant discoveries of Devonian that has survived. It is a popular visiting site for students and scholars reaching the "English Riviera" where it is located.

Devonian sandstone explosed by erosion. Shetland, Scottish Isles.
Landforms EU  

(* the text is based mostly on information from English wikipedia)

No comments:

Post a Comment