## 1 Introduction
The other large hydration form found in the forest near Walkenried was Walschmiede (Forest Forge). Its dimensions in 1933 were 10.0 \(\times\) 7.0 \(\times\) 1.9 m [68] and its inner cave measured a few years earlier was 8.0 \(\times\) 7.5 \(\times\) 2.0 m in size [53]. The height of this growing cave was 2.3 m, although their lateral sizes shrunk [1; 58]. Another hydration form of extraordinary size is the Ramesh Cave in the Dingwall quarry, with dimensions of 9.95 \(\times\) 4.10 \(\times\) 1.32 m [8]. Documented sizes of hydration caves are often changeable and grow or decrease with time [4; 9; 49]. A detached rock layer is commonly from a few cm to several tens of cm thick [5; 6; 18; 53; 61; 5], and in extreme cases, in side parts of forms 200 cm thick [9]. The thicker layers, as a rule, occur above the largest hydration caves [45]. Until now, the most frequently used methods in the study of hydration forms were standard geological and geomorphological observations, drawing and photographing. Measurements of the most important dimensions, such as length, width and height, were made with a ruler, but also a laser rangefinder. Moreover, the azimuth of elongation was measured with a geological compass and location was noted by a GPS device [18; 48]. Terrestrial photogrammetry was recently used at Pisky, which, in combination with ArcGIS (Esri, Redlands, CA, USA) and Photoscan (Agisoft LLC, St. Petersburg, Russia) computer programs, was the basis for supplementary morphometric measurements [57; 60]. To measure the change in the distance between the two points in time, the benchmark method with metal bolts was used [6; 60]. At Dingwall, [PERSON] [48] applied statistical analysis of measured geomorphometric parameters of 69 hydration landforms (Table 1), calculating, inter alia, the average or the minimum and maximum value, and also calculated unknown parameters on the basis of already determined dimensions. However, Dingwall does not yet have detailed and comprehensive documentation of aerial and terrestrial photogrammetry and geomorphometric analysis based on these data. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Site Name/ Province/ Country** & **Pisky/ Lviv Oblast/ Ukraine** & **Walkeried/ Lower Savony/ Germany** & **Alebastrovyye Islands/ Norway Zemlya/Russia** & **Dingwall/ Nova Scotia/ Canada** \\ \hline References & [7; 13; 18; 20; 54; 55; 56; 57; 58; 59; 60] & [1; 2; 4; 6; 7; 49; 51; 68] & [5] & [6; 7; 8; 9; 14; 48; 61] \\ \hline Number of documented hydration forms & 99 & 26 & unknown number & 69 * \\ \hline Area with & & & & \\ hydration & 200 \(\times\) 300 m & 1300 \(\times\) 600 m & 800 \(\times\) 150 m & 1800 \(\times\) 1400 m \\ relief & & & & \\ \hline Range of & length: 0.58–18.1 m & length: \(<\)10 m & length: 3–15 m & length: \(<\)25 m \\ dimensions & width: 0.32–15.5 m & width: 7.0 m & width: 1–10 m & width: 0.8–8.2 m \\ of hydration forms & height: 0.05–3.0 m & height: \(<\)3 m & height: 0.5–1.5 m & height: 0.1–2.4 m \\ \hline Range of & length: \(<\)9.5 m. & length: \(<\)10 m & length: unknown & length: \(<\)10.7 m \\ dimensions & width: \(<\)7.8 m & width: \(<\)7.5 m & width: unknown & width: \(<\)6.6 m \\ of inner hydration caves & height: \(<\)2.4 m & height: \(<\)2.3 m & height: \(<\)1.5 m & height: \(<\)1.32 m \\ \hline \hline \end{tabular}  
*—data after [PERSON] [48].  
\end{table} 
Table 1: Morphometric data of anhydrite hydration landforms (including pressure ridges at Dingwall) and hydration caves at Pisky, Walkenried, the Alebastrovyye Islands and Dingwall. Morphometric three-dimensional features, sizes and spacings are crucial for characterizing any landform [29] and also for remote recognition of them both on Earth and the other planets [30; 69]. Hydration forms of relief analogous to terrestrial ones can potentially be present on Mars [70]. The aim of this paper is to give the geomorphometric characteristics of the anhydrite hydration landforms from Dingwall.