Uncertainty is inherent in science built on previous results. In geoscience, for instance, researchers analyzing volcanic deposits assess the uncertainty around past deposit classifications. To aid this assessment, we followed a design by immersion approach to co-design uncertainty visualizations. We observed that besides visualizing it, it is challenging even to define what constitutes uncertainty, as how researchers understand and process uncertainty evolves. This motivated us to reach other members of the community to better understand how they integrate uncertainty in their work. Informed by a series of interviews, we first redesigned our visualization system and then introduced it as a technology probe to a broader community of geoscientists. Our results highlight that uncertainty in science is malleable and that visualization systems should be designed with this malleability in mind. Through a set of design implications, we advocate for visualizations that promote user agency and flexibility in defining and processing uncertainty.