Question

which correctly lists three different geologic features that help scientists determine the relative ages of rocks by their positions?
o magma, erosion, and intrusions
o erosion, magma, and cross - cutting relationships
o intrusions, index fossils, and magma
o index fossils, intrusions, and cross - cutting relationships

Explanation:

Index fossils are useful for dating rock layers as they are from species that existed for a relatively short time. Intrusions (igneous rock formations that cut through existing rocks) and cross - cutting relationships (where one geological feature cuts through another) are also important for determining relative ages. Magma is just molten rock material and not a feature for relative age determination by position. Erosion can remove rock layers but is not directly a feature for relative age determination by position in the way the correct features are.

Answer:

index fossils, intrusions, and cross - cutting relationships