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Rift shoulders are significant topographic features, often reaching elevations of several kilometers, that form mountainous belts along the edges of central
Examples of geological shoulders are:
* Geological shoulders of the
In geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
, a geological shoulder or rift shoulder is an area of uplifted terrain resulting from the compensatory movement of large-scale tectonic processes. These features are distinct from reliefs caused by compressional tectonics, as they arise from extensional forces rather than compression.
Geological shoulder
Rift shoulders are significant topographic features, often reaching elevations of several kilometers, that form mountainous belts along the edges of central rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...
depressions. The origin of these shoulders has been the subject of extensive research since the 1980s. The isostatic compensation model proposed by Felix Andries Vening Meinesz in 1950, also known as the isostatic or flexural rebound model, explains the permanent topographic uplift that occurs during rifting
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear Fault (geology), downfaulted depression, called a graben, or more commonly ...
and persists on passive margin
A passive margin is the transition between Lithosphere#Oceanic lithosphere, oceanic and Lithosphere#Continental lithosphere, continental lithosphere that is not an active plate continental margin, margin. A passive margin forms by sedimentatio ...
s despite erosion. This model is complemented by additional theories that account for factors such as creep, mantle magma underplating, or dynamic support. These explore the influence of rheological parameters, extension rates, crustal thickness, and fault geometry in greater detail.
Examples
Examples of geological shoulders are:
* Geological shoulders of the East African Rift
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...
;
* Margins of the Red Sea
The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...
;
* Cantabrian Mountains
The Cantabrian Mountains or Cantabrian Range () are one of the main systems of mountain ranges in Spain.
They stretch for over 300 km (180 miles) across northern Spain, from the western limit of the Pyrenees to the Galician Massif ...
and Armorican Massif
The Armorican Massif (, ) is a geologic massif that covers a large area in the northwest of France, including Brittany, the western part of Normandy and the Pays de la Loire. It is important because it is connected to Dover on the British side o ...
, forming the shoulders of the Bay of Biscay
The Bay of Biscay ( ) is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Point Penmarc'h to the Spanish border, and along the northern coast of Spain, extending westward ...
;
* Passive margins of the Atlantic Ocean: northern eastern Greenland and western Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...
;
* Passive margins of the Mascarene Basin (resulting from Indo-Madagascan rifting): eastern Madagascar and western India.
These examples highlight the global distribution of geological shoulders and their association with major tectonic features.
See also
*Geomorphology
Geomorphology () is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand wh ...
* Mantle convection
Mantle convection is the very slow creep of Earth's solid silicate mantle as convection currents carry heat from the interior to the planet's surface. Mantle convection causes tectonic plates to move around the Earth's surface.
The Earth's l ...
References
{{Reflist Structural geology Tectonics Geomorphology Geological processes Rifts and grabens