page_title: Ecca Group
section_title: Stratigraphic units
hierarchical_section_title: Ecca Group / Stratigraphic units
caption_attribution_description: English: A fossil Mesosaurus tenuidens (syn.Mesosaurus brasiliensis), Permian (270 myo), Parana basin, Brazil. Photographed at Dinoday 2009.
context_page_description: The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian in age.
context_section_description: The Ecca Group comprises sixteen recognized geological formations. These individual formations have been grouped into three geographical areas, which are the southern, western/northwestern, and northeastern facies successions. In the east of South Africa there are deposits of as of yet undifferentiated mudstone sequences attributed to the Ecca Group.
  With the exception of the Prince Albert, Whitehill, Collingham, and the uppermost Waterford Formations which are found in both the southern and western/northwestern facies, the geological formations of the Ecca Group can only be found in one of the three previously aforementioned facies successions. This is because each of these facies successions represents differing preserved environments that can be observed in their diagnostic geological features. The facies successions, along with their geological formations, are described below:
  Western/Northwestern Ecca facies
  This facies succession is purely marine. The rocks contain a complete transition, grading laterally into one other, from basin-floor marine deposits through to channelized submarine slope to shelf, pro-delta and beach environment deposits. The deposits of the western/northwestern facies fall within the Tanqua Depocenter, one of the vast submarine fan systems known from the marine Ecca. Associated formations are listed below (from oldest to youngest):
  Prince Albert Formation: In the west/northwestern facies the Prince Albert Formation is characterized by either greyish or olive micaceous or silty shale, carbonaceous shale, and rhythmites. Wackes and arenites are found in the northernmost section of the western/northwestern facies, and upward-fining sandstone and siltstone sequences that often contain ice rafted debris are a character diagnostic of its western outcrops. These rock sediments were deposited in a deep marine and distal submarine fan setting, and various invertebrate marine fossils, the chimaeroid cartilaginous fish Dwykaselachus oosthuizeni, palaeoniscoid fishes, and coprolites have been recovered from this formation.
  Whitehill Formation: Mudrock and shale dominant in the west/northwestern facies. The shale rock in this formation weather out white on the surface, often referred to in literature as the “white band”. It is the main diagnostic feature of this formation in this facies succession. The shales are carbonaceous and contain lenses of pyrite and chert. Fossil plant matter, palaeoniscoid fish, and arthropod remains are frequently found. The shales are considered to have been deposited in a suspension setting under anoxic, although shallower, sea floor conditions. Rare marine reptile fossils, most notably of Mesosaurus tenuidens, and another mesosaurid, Stereosternum tumidum, have been recovered from this formation.
  Collingham Formation: Is composed of thin beds of siliceous, dark grey mudstone alternated with softer, yellow-grey tuff beds. The fine-grained nature of the sediments indicate that the depositional environment was a low energy suspension setting in a submarine fan environment. The presence of tuff beds indicates that volcanic activity took place during the time of sediment deposition.
  Tierberg Formation: Predominantly composed of blackish, planar, argillaceous shales. Tuff beds are found in the lower sections of this formation while calcareous concretions and clay pellet conglomerates are found in the upper sections. Upwards-coarsening sequences of mudstones, siltstones, and sandstones that exhibit ball-and-pillow structures are also found in the uppermost sections. The presence of the shales in the lower Tierberg indicate a low energy marine environment that transitioned to pro-delta to distal delta depositional environments with the appearance of the upward coarsening sequences and other associated geological features. Various invertebrate fossils have been recovered, namely fish scales, sponge spiracles, and trace fossils of Planolites and Nereites.
  Skoorsteenberg Formation: Only found in the southernmost area of the western facies. A lens-shaped formation composed of five sandst
caption: A fossil Mesosaurus tenuidens (syn.Mesosaurus brasiliensis), Permian (270 myo)
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot A550", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2009:03:07 09:48:02", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "196", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1712", "Thumbnail JPEGInterchangeFormatLength": "8055", "EXIF ExposureTime": "1/60", "EXIF FNumber": "71/10", "EXIF ISOSpeedRatings": "80", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2009:03:07 09:48:02", "EXIF DateTimeDigitized": "2009:03:07 09:48:02", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ShutterSpeedValue": "189/32", "EXIF ApertureValue": "181/32", "EXIF ExposureBiasValue": "0", "EXIF Flash": "Flash fired, auto mode, red-eye reduction mode", "EXIF FocalLength": "29/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2490", "EXIF ExifImageLength": "1519", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "2490", "Interoperability RelatedImageLength": "1519", "EXIF InteroperabilityOffset": "1540", "EXIF FocalPlaneXResolution": "40960/3", "EXIF FocalPlaneYResolution": "2304000/169", "EXIF FocalPlaneResolutionUnit": "2", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Custom", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}