Accelerated disintegration of in situ disconnected portions of sandstone outcrops

Backwasting rock sheets of the Navajo Sandstone, Utah, USA

“…Salt weathering forms small‐scale tafoni and honeycombs on steep cliffs of the region (Mustoe, 1983). This interpretation is consistent with modern climate and with negative feedback between gravity loading and weathering (Bruthans et al, 2014, 2018; Filippi et al, 2021). Overhung alcoves are also common along plateau cliffs, and Bruthans et al (2017) noted that few of these large sandstone landforms are actively forming today.…”

“…Distinctive sandstone landforms are widespread globally, and the weathering processes driving their development have drawn widespread attention (Bruthans et al, 2014; Filippi et al, 2021; Huinink et al, 2004; Ostanin et al, 2017; Turkington & Paradise, 2005; Young & Young, 1992). When water moving through the vadose zone evaporates or freezes on large, steep‐walled sandstone landforms, it generates a diverse array of voids with distinctive shapes and patterns that range in size from centimetres (tafoni, honeycombs, and arcades; Bruthans et al, 2018; Filippi et al, 2018; Huinink et al, 2004; Mustoe, 1983) to hundreds of metres (overhangs and alcoves; Bruthans et al, 2017; Laity & Malin, 1985).…”

“…Studies of granular disintegration on cliff faces have shown that the occurrence, distribution, and shape of pits on cliff faces are controlled by the rate of water delivery on the cliff face relative to evaporative loss (Bruthans et al, 2018; Huinink et al, 2004) and by planar, low‐angle discontinuities in cliff‐forming rock (Filippi et al, 2018). Gravity loading stress reduces weathering and erosion rates (Bruthans et al, 2014, 2018; Filippi et al, 2018, 2021; Ostanin et al, 2017; Řihošek et al, 2016). When rock masses become detached from bedrock by horizontal and gently sloping fractures, they dilate more easily and become more susceptible to disaggregation via crystallization of salt or ice (Filippi et al, 2018, 2021; Safonov et al, 2020).…”

“…Gravity loading stress reduces weathering and erosion rates (Bruthans et al, 2014, 2018; Filippi et al, 2018, 2021; Ostanin et al, 2017; Řihošek et al, 2016). When rock masses become detached from bedrock by horizontal and gently sloping fractures, they dilate more easily and become more susceptible to disaggregation via crystallization of salt or ice (Filippi et al, 2018, 2021; Safonov et al, 2020). Topography can perturb gravitational stresses in surprising ways (Clair et al, 2015; Martel, 2016), but the effects of such perturbations on granular disintegration have not been considered in this study of small‐scale landforms.…”

Coastal honeycombs (Tuscany, Italy): Moisture distribution, evaporation rate, tensile strength, and origin

“…A Schmidt Hammer and Equotip are the most used devices to characterize weathering damage with great advantage, while being nearly non-destructive (Viles et al, 2011). It has recently been demonstrated that tensile strength measured in situ shows a greater sensitivity to weathering damage than both Schmidt Hammer readings (Bruthans et al, 2012) and drilling resistance (Filippi et al, 2021). Thus we selected in situ tensile strength of the rock surface as the parameter characterizing the degree of material damage at both honeycomb pits and lips.…”