See the problem?"
Yes, I know this is an article of faith amongst anti-evolutionists, but it's simply not true.
All geological dating is based ultimately on radio-metric techniques, plus a thorough understanding of how various geological processes work.
If I might cite an example: on the Columbia River in the state of Washington are canyons which geologists determine were caused by "outburst-floods" from Lake Missoula in the "recent" geological past -- circa 15,000 years ago.
These floods were caused by the lake periodically breaking through ice dams.
Canyons resulting from outburst-floods are distinct and there's no mistaking them for other types of canyons, for example, the Grand Canyon.
Where Columbia River canyons were quickly formed by outburst-floods, the Grand Canyon was formed over millions of years by the Colorado River slowly cutting down through the rising plateau around it.
Indeed, where the Grand Canyon does include at least one example of out-burst flooding, evidences of it are distinct from other sections of canyon.
Point is, there's no mistaking those two processes.
Even without radio-metric dating, they are obvious to trained geologists.
Radio-metric dating simply confirms what their own detailed studies already tell them.
Yes, fossils found in one location can help date those exact same fossils in another location, as can recognized geological strata.
Doubtless the best known example of that is the famous K-T boundary, which separates dinosaurs from everything which came afterwards.
That boundary is distinct enough, and has been radio-metrically dated often enough, that a trained geologist on seeing it can instantly know its age and composition.
Point is: notwithstanding your article of faith to the contrary, there's nothing "circular" about dating of fossils.
Results of outburst-flooding on Columbia River:
Compare to Grand Canyon formed over millions of years: