Foundered strata
Encyclopedia
Foundered strata is a term used by the British Geological Survey
in its maps and geological memoirs, and indeed by other authors, to describe rock strata which has collapsed due for example to the dissolution
of underlying strata.
Foundered strata may retain its original bedding
more or less intact or else it may assume a chaotic structure in the process of collapse or indeed some intermediate state of disruption.
Examples of foundered strata are evident along the northern margin of the outcrop of the Twrch Sandstone
(the former Basal Grit of the Millstone Grit
) in the Brecon Beacons National Park of South Wales
. The immediately underlying Carboniferous Limestone
has dissolved away in numerous locations such as at Pwll Byfre and resulted in the wholesale collapse of the sandstone beds above it. It is thought that the sandstone has been let down several hundred feet in places due to the removal by solution of limestone strata.
British Geological Survey
The British Geological Survey is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS headquarters are in Keyworth, Nottinghamshire, but other centres...
in its maps and geological memoirs, and indeed by other authors, to describe rock strata which has collapsed due for example to the dissolution
Dissolution (chemistry)
Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent. For liquids and gases, the molecules must be compatible...
of underlying strata.
Foundered strata may retain its original bedding
Bedding
Bedding refers to the materials laid above the mattress of a bed for hygiene, warmth, to protect the mattress, and for decorative effect. Bedding is the removable and washable portion of a human sleeping environment. It is more easily and economically replaced than the bed itself...
more or less intact or else it may assume a chaotic structure in the process of collapse or indeed some intermediate state of disruption.
Examples of foundered strata are evident along the northern margin of the outcrop of the Twrch Sandstone
Marros Group
The Marros Group is the name given to a suite of rocks of Namurian age laid down during the Carboniferous period in South Wales. These rocks were formerly known as the Millstone Grit Series but are now distinguished from the similar but geographically separate rock sequences of the Pennines and...
(the former Basal Grit of the Millstone Grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
) in the Brecon Beacons National Park of South Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
. The immediately underlying Carboniferous Limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...
has dissolved away in numerous locations such as at Pwll Byfre and resulted in the wholesale collapse of the sandstone beds above it. It is thought that the sandstone has been let down several hundred feet in places due to the removal by solution of limestone strata.