Question

1. Identify the type of rock given below and put them under the correct heading
a. Slate
d. Basalt
g. Marble
b. Graphite
e. Sandstone
c. Limestone
f. Gypsum


METAMORPHIC SEDIMENTARY IGNEOUS

Answer 1

Answer:

There are two main types of metamorphic rocks: those that are foliated because they have formed in an environment with either directed pressure or shear stress, and those that are not foliated because they have formed in an environment without directed pressure or relatively near the surface with very little pressure at all. Some types of metamorphic rocks, such as quartzite and marble, which also form in directed-pressure situations, do not necessarily exhibit foliation because their minerals (quartz and calcite respectively) do not tend to show alignment (see Figure 7.12).

When a rock is squeezed under directed pressure during metamorphism it is likely to be deformed, and this can result in a textural change such that the minerals are elongated in the direction perpendicular to the main stress (Figure 7.5). This contributes to the formation of foliation.