in adult animals, are a source of undifferentiated cells that can divide to produce cells that can specialize.

1. law of superposition: when there are horizontal layers of rock. the layers at the top are the youngest.

2. law of uncomformity: where one layer is much younger than the previous one, therefore creating a gap in the time record.

3. inclusion: when there is a solid stone inside of another.

4. intrusion: a feature formed when a stone is filled with magma.

hope i answered your question.