Abstract For the first time, we present a decadal-scale stable isotope record (δ 18 O, δ 13 C) of 67 speleothem calcite samples coming from an artificial tunnel network located in Graz, Austria. Stable isotope data are interpreted with the help of time series (TS) analysis of mean air temperatures (MAT) and mean annual precipitations (MAP) that have been monitored and recorded in a neighbouring meteorological station. Speleothem records have proved to be very useful in reconstructing changes of environmental conditions. For studied stalagmites, which grew between 1945 and 2018, the δ 18 O values average −18.64‰ and range from −23‰ to −17‰ (VPDB, Vienna Pee Dee Belemnite), suggesting variable climatic conditions. The δ 18 O values of calcite increase along the growth axis and are correlated with high temporal resolution MAT, MAP and weighted mean annual δ 18 O of precipitations. For the same time interval, while the temperature TS show an increasing trend, with a steeper gradient since the 1980s, the precipitation TS presents a weak decreasing tendency. Increase in the δ 13 C values of speleothems from −33‰ to −24‰ (VPDB) is correlated with increasing temperature and drought, associated CO 2 degassing and soil erosion over the tunnel system.

Abstract Based on existing classifications of caves that often involve descriptive terms, a classification is presented that is based purely on genetic processes. An attribute key is developed that allows the classification of caves by means of cave maps, photographs and reports. This method is applied to a dataset of 6007 caves in a study area in eastern Austria. The area comprises diverse geological units of the Eastern Alps and the southern Bohemian Massif. A total of 94% of the caves could be classified with the surprising result that mechanical weathering and erosion caves are almost as common as solution caves even though the vast majority of caves are developed in carbonate rocks. Field checks confirmed the result and showed that the error is acceptable. The classified caves can also be used as indicator of natural phenomena like gravitational mass movements or vulnerable karst areas by decision-makers non-specialized in cave genesis.