Answer:
Cross-cutting relationships
Step-by-step explanation:
Sometimes old rocks are affected by other geological features, as when molten lava forces its way through fractures in several layers on its way to the surface. The assumption that the intruding features must be younger than the layers of rock on which they intrude is called the law of cross cutting relationship.
Law of cross-cutting relationship explains than an igneous intrusion is always younger than the rock it cuts across i.e that rock formations that cut across other rocks must be younger than the rocks that they cut across. This law is useful in establishing the relative ages of faults and igneous intrusion in sedimentary rocks in relative dating technique in geology.
Cross cutting relationship gives geologist the relative idea of which rock came first and so on