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Structural dome on Baffin Island, seen in a planation surface. Oblique aerial photo of Upheaval Dome, Utah. Now considered to be a deeply-eroded impact crater, it was for many years believed to be a salt dome. Caprock of a salt diapir at Cape Breton, Nova Scotia. The white rocks at left center are the gypsum and anhydrite carapace of the diapir.
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A lava spine or lava spire is a growth that can form on the top of a lava dome. A lava spine can increase the instability of the underlying lava dome. A recent example of a lava spine is the spine formed in 1997 at the Soufrière Hills Volcano on Montserrat.
The top and side margins of an inflating lava dome tend to be covered in fragments of rock, breccia and ash. [71] Examples of lava dome eruptions include the Novarupta dome, and successive lava domes of Mount St Helens. [72] When a dome forms on an inclined surface it can flow in short thick flows called coulées (dome flows).
Lava domes are common features on volcanoes around the world. Lava domes are known to exist on plate margins as well as in intra-arc hotspots, and on heights above 6000 m and in the sea floor. [1]
A laccolith is a body of intrusive rock with a dome-shaped upper surface and a level base, fed by a conduit from below. A laccolith forms when magma (molten rock) rising through the Earth's crust begins to spread out horizontally, prying apart the host rock strata. The pressure of the magma is high enough that the overlying strata are forced ...
A bornhardt (/ ˈ b ɔːr n ˈ h ɑːr t /) is a dome-shaped, steep-sided, bald rock outcropping at least 30 metres (100 ft) in height and several hundred metres in width. [1] They are named after Wilhelm Bornhardt (1864–1946), a German geologist and explorer of German East Africa , who first described the feature.
Granite domes are domical hills composed of granite with bare rock exposed over most of the surface. Generally, domical features such as these are known as bornhardts . Bornhardts can form in any type of plutonic rock but are typically composed of granite and granitic gneiss . [ 1 ]