Yea it is right 1950. Geography !
<u>Answer</u>:
Sedimentary rocks are changed to metamorphic rocks through subduction and <u>the increase in temperature</u>.
<u>Explanation</u>:
Rocks are of three types such as igneous, sedimentary and metamorphic rocks. Igneous rocks are formed due to volcanic magma and sedimentary rocks are formed from the agents of erosion. Igneous and sedimentary rocks are changed in to metamorphic rocks through subduction and the increase in the temperature.
Through over a period of time, high pressure and high temperature caused the transformation of sedimentary rocks in to metamorphic rocks. Metamorphic rocks consists of several minerals such as kyanite, andalusite, garnet, mica, amphiboles and so on.
It is always a given that the compass points towards the magnetic north and not the true north. The magnetic declination is the angle between the magnetic north and the geographic north. It varies from time to time due to the constantly shifting magnetic field.
There are three types of magma: basaltic, andesitic and rhyolitic magma. Basaltic magma have a characteristic runny liquid magma which contains low silica content. Andesitic magma is the intermediate one in terms of silica content and viscosity. The rhyolitic magma is the thick, high silica content magma.