| Senni Beds | |
|---|---|
| Stratigraphic range: Devonian | |
 Mynydd Troed, the upper part of the hill consisting of the Senni Beds Formation | |
| Type | Formation |
| Unit of | Old Red Sandstone |
| Lithology | |
| Primary | Mudstone |
| Other | Sandstone |
| Location | |
| Region | Wales |
| Country |  United Kingdom |
The Senni Beds is the former name of the Senni Formation in Wales. It preserves fossils dating back to the Devonian period.
Waun Fach is, with a summit height of 811 metres (2,661 ft), the highest mountain in the Black Mountains in south-eastern Wales. It is one of the three Marilyns over 600 m that make up the range, the others being Black Mountain and Mynydd Troed. To the north Rhos Fawr and the Radnor Forest can be seen. It is the third highest mountain in Britain south of Snowdonia. It is situated at the head of the Grwyne Fechan valley, above and to the west of the Grwyne Fawr reservoir. It has an undistinguished rounded summit. The nearby tops on the ridge, Pen Trumau and Pen y Gadair Fawr, although lower, are very much more recognisable.
Ysgyryd Fach is a hill one mile east of Abergavenny in the county of Monmouthshire, south Wales. It is often referred to in English as 'Little Skirrid' or sometimes as 'Skirrid Fach'. Its summit height is just over 270 metres (885'). A conifer plantation extends over much of the hill including its summit; prior to felling of trees on the upper slopes in 2012 outward views were therefore restricted. The hill is considered to be one of the 'seven hills of Abergavenny'.
Pen Allt-mawr is a 719 metres (2,359 ft) high subsidiary summit of Waun Fach and the third highest peak in the Black Mountains in south-eastern Wales. A very recognisable and prominent peak of the Black Mountains, it lies near the end of the more westerly of Waun Fach's two broad southern ridges. Its top Pen Twyn Glas is to the north, while its close neighbour Pen Cerrig-calch is to the south. A prominent spur 1 km to the SSW of the summit is known as Pen Gloch-y-pibwr. The stepped Bryniog ridge curves southward from this point.
Hostinella is a form genus, used for bare dichotomously branching stems (axes) which have not been found in association with spore-forming organs or sporangia and so cannot be assigned to a more precise genus or species. Specimens assigned to this genus have been found in Bathurst Island, Canada, in the Bertie Formation of Upper Silurian age, where the stems are approximately 1.2 mm in diameter; and in Lower Devonian Senni beds where the axes have a straited external appearance and contain xylem with tracheids.
Heol Senni Quarry is a disused quarry in Brecknockshire, Powys, Wales. It is a Site of Special Scientific Interest because of the geological strata it reveals and the fossil remains of pterapsids which have been found here. The quarry is also used recreationally for paragliding.
The Detroit River Group is a geologic group in Michigan and Ohio. It preserves fossils dating back to the Devonian period.
The Traverse Group is a geologic group in Michigan, Indiana and Ohio comprising middle Devonian limestones with calcareous shale components. Its marine fossils notably include Michigan's state stone, the Petoskey stone, among other corals and records of ancient marine life. A range of trilobites has also been found in the Traverse Group.
The Ohio Shale is a geologic formation in Ohio. It preserves fossils dating back to the Devonian period.
The Dundee Limestone is a geologic formation in Michigan, Ohio and Ontario. It preserves fossils dating back to the Devonian period.
The Ashokan Formation is a geologic formation in eastern New York located in the Catskill Mountains. This formation is Devonian in age. The formation consist of cross bedded dark grey sandstone. The Ashokan was formed on the coastal fluvial delta platform to the west of the Taconic Mountains.
The Ouray Formation is a geologic formation in Colorado. It preserves fossils dating back to the Devonian period.
The Amherstburg Formation is a geologic formation in Ontario, Canada and Michigan, United States. It preserves fossils dating back to the Devonian period.
The Disappointment Bay Formation is a geologic formation in Nunavut, extending from Ellesmere Island in the east to Bathurst Island in the west. It preserves fossils dating back to the Devonian period, primarily of invertebrates.
The Alexo Formation a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation consists primarily of dolomite. It is locally fossiliferous and includes remains of marine animals such as brachiopods and conodonts.
The St. Maughan's Formation is a geologic formation in Wales. It preserves fossils dating back to the Devonian period.
The Sandwick Fish Beds is a geologic formation in Scotland. It preserves fossils dating back to the Devonian period.
The Furse Argillaceous Beds is a geologic formation in Scotland. It preserves fossils dating back to the Devonian period.
The Bois Blanc Formation is a geologic formation in Michigan. It preserves fossils dating back to the Devonian period.
The Ellsworth Shale is a geologic formation in Michigan. It preserves fossils dating back to the Devonian period.
Heightingtonaspis is an extinct genus of primitive arthrodire placoderm fish from the Devonian period in Great Britain, and currently contains three species.
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