Scawt Hill
| Scawt Hill | |
|---|---|
Scawt Hill from the Sallagh Road, Cairncastle
|
|
| Highest point | |
| Elevation | 378 m (1,240 ft) |
| Coordinates | 54°54′38″N 5°54′55″W / 54.9105°N 5.9154°WCoordinates: 54°54′38″N 5°54′55″W / 54.9105°N 5.9154°W |
| Geography | |
 Location in Northern Ireland
|
|
| Location | County Antrim, Northern Ireland |
| OSI/OSNI grid | D338090 |
| Topo map | OSNI Discoverer 9 |
| Geology | |
| Mountain type | Volcanic plug |
Scawt Hill is a volcanic plug in County Antrim, Northern Ireland, in the borough of Larne, 5 km from the village of Ballygalley.
It gets its name from the Ulster Scots 'scawd' meaning scaly, scabby or rugged. Alternately, 'scawt' meaning scruffy and contemptible, and when applied to rocks, covered in barnacles.
Scawt Hill is notable for being the type locality for several hydrated calcium silicates, that is, the place where they were first identified. These minerals were formed when the existing chalk of the area was intensely altered by the intrusion of the feeder tube of an ancient volcano, now long since cooled and eroded to its roots.
Minerals that were first discovered at Scawt Hill:
In all, 28 minerals have been found at this site.
Over 30 volcanic plugs are dotted through Northern Ireland, mostly along the Antrim coast like Scawt Hill, although they are relatively rare throughout the rest of Ireland. Volcanic plugs are often easy to spot. Their harder rock erodes away more slowly than their surroundings so they rise above the landscape as a hill.
The largest volcanic plug in Northern Ireland is the oval-shaped Slemish. At its widest, Slemish is over 1 km in diameter. Scawt Hill is more of a typically sized example. This olivine dolerite plug is 270 m x 180 m wide and rises 30 – 60 m above the Cretaceous white limestone, although the Antrim plateau around it is typically basalt.
The chalk at Scawt Hill has been transformed by high temperature and low pressure thermal metamorphism, developing the large and unusual range of calc-siliate minerals that have attracted interest. The rocks inside the vent were also changed by the contact, producing a sequence of alkali mafic igneous rocks as the magma assimilated the chalk, reducing the silica in the magma and leading to larger grain size near the contact.
...
Wikipedia