Final answer:
A volcanic dy ke is a type of thin pluton that cuts across existing rock layers and is younger than the rocks it cuts through.
Step-by-step explanation:
The type of thin pluton that cuts across existing layers of rock is known as a volcanic dy ke. Volcanic dy kes are a form of igneous intrusion and they exhibit cross-cutting relationships, which is a principle in geology that helps determine the relative ages of geological structures.
According to this principle, if a body of rock cuts through another, the one that is cutting is younger. Therefore, when a volcanic dy ke is observed cutting through other rock layers, such as sedimentary or metamorphic rocks, it implies that the intrusion of the dy ke occurred after the existing rock layers had already formed.