Railroad beds are often stabilized with gravel or cobble-sized stones, and in places like Florida, where there is little natural stone available, Georgia granites are often brought in for this purpose. I can imagine geologists of the future trying to explain long linear features of granitic rock across what used to be sedimentary Florida (the rails, ties and spikes would quickly rust or dissolve away).

Non-native rocks are also used as breakwaters and rip-rap, and as construction materials. Many would be preserved in situ, others would be dispersed or assembled by geologic processes. Most of our manufactured products would erode or dissolve, but it can't be ruled out that some would survive. After all, even delicate biological specimens have been found as intact fossils hundreds of million years after their deposition.