How is a dike formed?
Dikes are tabular or sheet-like bodies of magma that cut through and across the layering of adjacent rocks. They form when magma rises into an existing fracture, or creates a new crack by forcing its way through existing rock, and then solidifies.
What is the difference between a dyke and a sill?
A sill is a concordant intrusive sheet, meaning that a sill does not cut across preexisting rock beds. In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source.
How was the intrusive dyke formed?
A dike (American spelling) or dyke (British spelling), in geological usage, is a sheet of rock that is formed in a fracture of a pre-existing rock body. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock.
What’s the difference between magma and lava?
Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth’s surface.
What is the sill in a volcano?
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet.
What is a dolerite dyke?
Dolerite is the medium grained, intrusive, equivalent of a basalt (link to basalts). It usually occurs as dykes, plugs or sills. Being intruded into country rocks at shallow levels, the magma has more time to cool than if extruded. On Arran, dolerite forms the majority of the sills and dykes seen.
What is the difference between a batholith and a stock?
A batholith is an exposed area of (mostly) continuous plutonic rock that covers an area larger than 100 square kilometers (40 square miles). Areas smaller than 100 square kilometers are called stocks.
What are the 3 major types of magma?
It also contains small amounts of dissolved gases such as water vapor, carbon dioxide, and sulfur. The high temperatures and pressure under Earth’s crust keep magma in its fluid state. There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition.
Where can sills be found?
Sills occur in parallel to the bedding of the other rocks that enclose them, and, though they may have vertical to horizontal orientations, nearly horizontal sills are the most common.
