VULCANICITY

CONTENT

1. Definition of Intrusive Vulcanicity
2. Features of Intrusive Vulcanicity
3. Meaning of Volcano
4. Classification of Volcanoes
5. Hot Springs and Geysers

Intrusive Vulcanicity

Definition of Intrusive Vulcanicity

Intrusive vulcanicity involves the solidification of molten magma within the earth’s crust.

Features of Intrusive Vulcanicity

The following are features of intrusive vulcanicity;

1. Dyke:

This is an intrusion which forms when magma solidifies within vertical faults. Dyke forms walls of hard rocks. Examples are Dykes of Cleveland in England.

2. Sill:

Sill is a sheet of solidified magma which lies horizontally as a result of intrusion along the bedding planes of sedimentary rocks. Examples are Northumberland in English, Salisbury Craig in Zimbabwe and the little and Great Karoo in South Africa.

3. Batholith:

This is a dome-shaped mass of igneous rock formed deep down in the crust. It is often composed of granite and extends for hundreds of kilometers. The formation of usually is attributed to the sinking in and resultant melting and incorporation of large blocks of surrounding area rocks into the molten magma which may later solidify.