Lewisian Gneiss
Lewisian gneiss is a type of metamorphic rock found in the Scottish Highlands, particularly in the northwest. It is Britains oldest rock and one of the oldest rocks on Earth, dating back to the Archean eon, approximately 3 billion years ago. This ancient rock formation provides a fascinating glimpse into the early history of our planet.
Lewisian gneiss is characterized by its banded appearance, which is caused by the alignment of minerals during the process of metamorphism. These bands often contain a variety of minerals, including quartz, feldspar, and mica. The rock's composition and texture vary depending on the specific conditions under which it formed.
Did you know?
Lewisian gneiss is a rare example of crustal rock that is so old and still exposed at the surface. Most rocks of this age have been deeply buried or recycled through plate tectonics. However, the Scottish Highlands have remained relatively stable over billions of years, preserving the Lewisian gneiss as a geological time capsule. This makes it a valuable resource for scientists studying the early history of the Earth.