VOLCANISM AND EARTHQUAKES 

   1. Landforms Associated with volcanic Activities

 volcanic activities have a profound influence on the earth's landforms. As we know, the Molten magma is situated beneath the earth surface. The molten magma is mobile rock that tries to find a way to the surface. ie, It forces its way into the planes of weakness of the crust to escape quietly  or explosively to the earth surface. The factors which determining the features of resultant landforms are  strength and fluidity of the magma, the types of cracks,faults and joints that it penetrates, and the manner in which it escapes to the surface. While moving out to the the surface magma may cool and solidify within the crust as plutonic rocks resulting in intrusive landforms. If it  reach the surface and solidify, form extrusive landforms. Rocks formed by either plutonic or volcanic activity are called igneous rocks

2. Landforms of Igneous Intrusions

  

2.1  Sills 

horizontal intrusion of molten magma along the bedding planes of sedimentary rocks called sill.        eg. Great Whin sill of N.E England

2.2 Dykes

similar intrusions when injectected vertically as narrow walls of igneous rocks within the sedimentary layers are called dykes

eg. Cleveland Dyke of Yorkshire, England

references..

certificate physical and human geography -gc leong

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