Replication and reinsertion of stalagmites sampled for paleoclimatic purposes

Abstract

Sampling stalagmites for paleoclimatic study can enter into conflict with preserving the beauty and integrity of caves. To minimize this impact, a variety of sampling strategies have been used by researches aware of cave-conservation issues. Based on our experience in two caves (El Soplao and La Buenita, Cantabria, N Spain), we propose to apply molding and casting laboratory techniques to create replicas of stalagmites, placing the replicas back in the original cave locations so that the impact of sampling to the cave is severely reduced. We provide detailed descriptions of the molding and casting methods, which vary depending on stalagmite size. For relatively small specimens (less than ~35 cm tall), we use a single-piece mold and two jackets. For larger stalagmites (~40-70 cm tall), we use a two-piece mold and two jackets. In a first casting step, we obtain a master piece in dental plaster that is preserved. In a subsequent casting step, we use epoxy resin to generate the replica that will be placed in the cave. We use extra-hard plaster coated with epoxy resin to fix the replicas to their original substrates. Both the epoxy resin and plaster are carefully dyed to match the original surface texture and color of the sampled stalagmites. Once in place, the stalagmite replicas are almost indistinguishable from the natural specimens.