GeoLog

Tectonics and Structural Geology

Imaggeo on Mondays: Metamorphosis

This fold is part of the metamorphic core of the Pyrenees. The shear zone is almost vertical, producing a small parasitic fold (a smaller fold within a larger one), which looks almost as if it continues into the sky. The metamorphic sediments are about 500 million years old and have been deformed several times, most recently during the alpine orogeny. The alpine orogeny was period of extensive mou ...[Read More]

Imaggeo on Mondays: Kalalau Valley

At over 5 million years old, the island of Kauai is the oldest island in the Hawaiian Achipelago. Hawaii, Maui and Oahu are all younger and lie further to the southeast. This island chronology is no coincidence – the Archipelago formed as a result of intra-plate volcanic activity. Intra-plate volcanism occurs where an upwelling magma plume or ‘hot spot’ lies beneath a continental plate. In this ca ...[Read More]

Geosciences Column: Hazard perception – how great is the risk of a rockfall?

In this month’s Geoscience’s column, Sara Mynott discusses the geological hazards associated with climate warming and how recent research sheds new light on our understanding of rockfall frequency. Rockfalls are the free-falling movement of bedrock material from a rock face, a phenomenon also encompassed by the terms ‘landslide’, ‘rockslide’ and ‘rock avalanche’. They range from small debris falls ...[Read More]

Imaggeo on Mondays: Rainbow in stone

Nothing better characterises the wild US West than endless landscapes of red hoodoos, spires of rock protruding from the bottom of an arid drainage basin or badland. Found mainly in desert and dry, hot areas, hoodoos are distinctive from similarly-shaped formations, such as spires or pinnacles, because their profiles vary in thickness throughout their length. Their distinctive colour bands are the ...[Read More]