Forest Sandstone Fm
Type Locality and Naming
Mid-Zambezi Basin, Cabora-Bassa Basin. Named by early geologists in the late 19th/early 20th century (often attributed to A.J.C. Molyneux around 1903) for the prominent, tree-covered sandstone ridges and escarpments found in the Zambezi Valley and around the Bulawayo region in Zimbabwe. Uppermost formation in Stormberg Gr in Mid-Zambezi Basin
Synonym:
Lithology and Thickness
Dominated by massive, very well-sorted, fine- to medium-grained quartzitic sandstones exhibiting large-scale aeolian (wind-blown) cross-bedding. The sandstones are typically white, pink, buff, or red. The basal portions of the formation sometimes contain minor lenses of red mudstone, siltstone, and localized calcareous concretions (calcrete) representing ephemeral fluvial or playa deposits.
Relationships and Distribution
Lower contact
Typically overlies the coarser, fluvial sediments of the Pebbly Arkose Fm (or the Escarpment grit Fm in older, broader classifications).
Upper contact
Sharply overlain by the massive continental flood basalts of the Batoka Basalt Fm (Karoo Volcanics).
Regional extent
Widespread across Zimbabwe, particularly prominent in the Mid-Zambezi basin in the north and the Save-Limpopo basin in the south. Upper Karoo / Stormberg Gr equivalent. It is the direct regional chronostratigraphic equivalent of the Clarens Fm in the Main Karoo Basin (South Africa), the Ntane Fm (Botswana), and the Etjo Fm (Namibia).
GeoJSON
Fossils
Age
Depositional setting
A vast continental aeolian erg (desert sand sea).
Additional Information
The Forest Sandstone forms spectacular geomorphological features in Zimbabwe, including the scenic cliffs of the Gonarezhou National Park (Chilojo Cliffs) and acts as an important regional groundwater aquifer.