Final answer:
Sam is performing annexation by creating a permanent walkway from stones, which transforms them from personal to real property.
Step-by-step explanation:
Sam is engaged in the act of annexation, which is the process of converting personal property into real property by permanently affixing it to the real estate. By constructing a walkway with loose stones, he is attaching what was previously personal property (movable stones) to the land, creating a permanent fixture. This can be contrasted with severance, which is the opposite process of removing fixtures from the land, turning them back into personal property.
Sam is constructing a walkway from his house to the detached garage using loose stones from his property. This action is an example of annexation, which is the process of adding or attaching something to a property. In this case, Sam is adding the walkway to his property by using the loose stones to construct it.