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The abandoned gypsum quarry at Dingwall, in Canada, is a unique place with a peculiar “living” landscape created by expansive hydration of anhydrite process actively operating in the weathering zone at the quarry bottom. It causes a rapid volume increase of the rocks and the formation of the unique domed and tepee-like hydration landforms (several meters in length and up to 2.09 m high) with internal hydration caves (swelling caves, German: Quellungshöhlen). The quarry also shows some rare evaporite minerals, sulphate karst, spheroidal weathering of anhydrite and the other phenomena. Several steps of geoconservation strategy are described to promote Dingwall quarry as a geosite and a geodiversity site: inventory, quantitative assessment, conservation, interpretation, promotion and monitoring. The performed inventory describes the elements of the geoheritage. The quantitative assessment of the site, made according to the method by Brilha (Geoheritage 8:119–134, 2016), was based on the four aspects: scientific value, potential educational use, potential tourist use and the rate of destruction. For showing the geological heritage, the plan of the site was prepared, with paths for visitors, attendant infrastructure, thematic interpretation panels and plates with QR codes. As a part of the promotion, application of the Internet with already operating sites (e.g. hydrationcave.com) is proposed. In turn, monitoring, with measurements of benchmarks and photographic and photogrammetric documentation, will ensure the proper functioning of the site after establishing it as a geosite and a geodiversity site.

The gypsum-anhydrite rocks in the abandoned quarry at Dingwall (Nova Scotia, Canada) are subjected to physical and chemical weathering, including hydration of the anhydrite, i.e., its transformation into secondary gypsum under the influence of water. This process is known to lead to the localized volume increase of the rock and the formation of spectacular hydration landforms: domes, tepees and ridges. Cavities appearing in the interior of these domes are often unique hydration caves (Quellungshöhlen in German). For the first time, this paper gives detailed geomorphometric characteristics of the 77 dome- and tepee-like hydration landforms growing today at Dingwall based on their digital surface models and orthophotomaps, made with the method of photogrammetry integrated with direct measurements. The length of hydration landforms varies from 1.86 to 23.05 m and the relative height varies from 0.33 to 2.09 m. Their approximate shape in a plan view varies from nearly circular, through oval, to elongated with a length-to-width ratio rarely exceeding 5:2. Length, width and relative height are characterized by moderate mutual correlation with proportional relations expressed by linear equations, testifying that the hydration landforms generally preserve the same or very similar shape independent of their sizes. The averaged thickness of the detached rock layer ranges from 6 to 46 cm. The size of the forms seems to depend on this thickness—the forms larger in extent (longer) generally have a thicker detached rock layer. Master (and other) joints and, to a lesser extent, layering in the bedrock influence the development of hydration landforms, particularly by controlling the place where the entrances are open to internal cavities or caves. Three structural types of the bedrock influencing the growth of hydration forms were recognized: with master joints, with layering and with both of them. The latter type of bedrock has the most complex impact on the morphology of hydration landforms because it depends on the number of master joint sets and the mutual orientation of joints and layering, which are changeable across the quarry. The durability of the hydration forms over time depends, among others, on the density of fractures in the detached rock layer.