GEOLOGY

Detailed explanation-1: -The principle of inclusions states that any rock fragments that are included in a rock must be older than the rock in which they are included. For example, a xenolith in an igneous rock, or a clast in sedimentary rock must be older than the rock that includes it (Figure 19.7).

Detailed explanation-2: -Inclusions are always older than the rock they are found in. Even if we did not see the igneous and metamorphic rocks in surface exposures, the fact that they occur in the (brownish) sediment unit indicates the presence of older ingneous and metamoprhic rocks that supply material to that unit.

Detailed explanation-3: -The principle of superposition states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. Logically a younger layer cannot slip beneath a layer previously deposited.

Detailed explanation-4: -The principle of inclusions states that any rock fragments that are included in rock must be older than the rock in which they are included.