The Ecca Group is the name given to the sedimentary

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

 geological formations found in Karoo

Karoo

The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...

 Basin region of Southern Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. It consists mainly of shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

s and sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

s, laid down in the sandy shorelines of swamplands, during the Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 Period.

In the Eastern Cape Province the Karoo Basin fill commenced with the deposition of the Dwyka Group

Dwyka Group

The Dwyka Group includes the sedimentary geological formations found in Karoo Basin region of Southern Africa. In the Eastern Cape Province the Karoo Basin fill commenced with the deposition of the Dwyka Group, followed by the Ecca Group, the Beaufort Group, the Molteno, Elliot, and Clarens...

, followed by the Ecca Group, the Beaufort Group

Beaufort Group

The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup of geological strata in Southern Africa. It follows conformably after the Ecca Group and consists essentially of sandstones and shales, deposited in the Karoo Basin from the Middle Permian to the early part of the...

, the Molteno

Molteno Formation

The Molteno Formation is a palaeontological formation of the Stormberg Group, located in the main Karoo Basin, South Africa. It dates to the Upper Triassic period and is rich in fossils....

, Elliot

Elliot Formation

The Elliot Formation is a geological formation dating to roughly 210 to 190 million years ago and covering the Norian to Sinemurian stages. The Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone, sandstone, and mudstone...

, and Clarens Formation

Clarens Formation

The Clarens Formation is a prominent fossil site in the Tuli Basin, in the KwaZulu-Natal region of South Africa.-Fauna of the Clarens Formation:Unidentified dinosaur eggs have been recovered from the formation.-Bony fish:-Dinosaurs:-Synapsids:...

s and the
igneous Drakensberg Group. The basin followed the typical evolution of foreland basins, with the Ecca Group representing the ‘flysch

Flysch

Flysch is a sequence of sedimentary rocks that is deposited in a deep marine facies in the foreland basin of a developing orogen. Flysch is typically deposited during an early stage of the orogenesis. When the orogen evolves the foreland basin becomes shallower and molasse is deposited on top of...

’ component and the Beaufort Group, the overlying Molteno and Elliot Formations representing the ‘molasse

Molasse

The term "molasse" refers to the sandstones, shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse is deposited in a foreland basin, especially on top of flysch, for example that left from the rising Alps, or erosion in the Himalaya...

’-fluvial type sediments.
It is a carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

-rich sedimentary deposit, owing to the high vegetation content of the original sediment. Coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 is mined in the Vryheid area.

Deposits in this group include (in order of deposition):

• Prince Albert Formation marine mudstones
  Mudstone
  Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
  
  .
• Whitehill Formation marine mudstones.
• Collingham Formation persistent grey shales
  Shale
  Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
  
  , alternating with yellow claystones
  Claystone
  Claystone is a geological term used to describe a clastic sedimentary rock that is composed primarily of clay-sized particles ....
  
   which derive from volcanic ash.
• Ripon Formation
• Fort Brown Formation
• Waterford Formation sandstones and shales .

The Pietermaritzburg Formation and the younger Vryheid Formation are also named deposits within the group.