GEOLOGY

Detailed explanation-1: -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. For example, a xenolith in an igneous rock or a clast in sedimentary rock must be older than the rock that includes it (Figure 8.6).

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: -To mineralogists, an inclusion is any material trapped inside a mineral as it forms. That material could be a rock trapped inside another rock. It can be a bug or a feather stuck in a glob of amber.

Detailed explanation-4: -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-5: -Principle of inclusions: The principle of inclusions states that a rock containing an inclusion (fragment of another rock) must be younger than the inclusion.