The Forest Sandstone is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number o ...

, dating to roughly between 200 and 190

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

and covering the Hettangian to

Sinemurian In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and ...

stages Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * S ...

of the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

Period in the Mesozoic Era. As its name suggests, it consists mainly of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

. Fossils of the

prosauropod Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had l ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

Massospondylus ''Massospondylus'' ( ; from Greek, (massōn, "longer") and (spondylos, "vertebra")) is a genus of sauropodomorph dinosaur from the Early Jurassic. (Hettangian to Pliensbachian ages, ca. 200–183 million years ago). It was described by S ...

'' and the primitive sauropod ''

Vulcanodon ''Vulcanodon'' (meaning "volcano tooth") is an extinct genus of sauropod dinosaur from the Early Jurassic of southern Africa. The only known species is ''V. karibaensis''. Discovered in 1969 in Zimbabwe, it was regarded as the earliest-known sau ...

'' have been recovered from the Forest Sandstone.

Geology

Description

The formation is a sedimentary unit, consisting mainly of aeolian sands and silts with interbedded fluvial sediments, laid down during a period of increasing aridity.

Extent

The Forest Sandstone is found in

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label= Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalaha ...

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are t ...

and

Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and ...

, in the Mid-Zambezi, Mana Pools, Cabora Bassa and Limpopo Basins, with its greatest thickness in the Cabora Bassa Basin.

Deposition

Age

The formation is dated at 200 to 190 Ma.

Stratigraphy

The Forest Sandstone is the penultimate formation in the Upper Karoo Group of the

Karoo Supergroup The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a peri ...

, lying above the Pebbly Arkose Formation and below the Batoka Formation. In the Thuli Basin it is sometimes referred to as the Samkoto Formation. The Forest Sandstone has been correlated to the

Clarens Formation The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of ...

of the Great Karoo Basin in South Africa.

Fossil content

Vertebrate fauna

Economic importance

Hydrogeology

The Forest Sandstone is the major groundwater-bearing unit of the Upper Karoo Group.

References

{{Reflist Geologic formations of Botswana Geologic formations of Zambia Geologic formations of Zimbabwe Jurassic System of Africa Early Jurassic Africa Hettangian Stage Sinemurian Stage Geologic formations with imbedded sand dunes Sandstone formations Aeolian deposits Fluvial deposits Fossiliferous stratigraphic units of Africa Paleontology in Botswana Paleontology in Zambia Paleontology in Zimbabwe