Ghost Rock A ghost rock, is it some sort of apparition of a rock from the past? Well yes of sorts. G

Ghost RockA ghost rock, is it some sort of apparition of a rock from the past? Well yes of sorts. Ghost rock karstification is a two stage erosional process that affects Limestones. The first stage is associated with the chemical weathering of limestone that leaves a ‘ghost-rock’ known as residual alterite. This can only form when there is a low hydro dynamic system allowing for non soluble composition of limestone to remain behind. The second stage is lead by mechanical weathering that erodes away the residual alterite leading to the traditional karstic morphology that is well recognised in limestone areas worldwide. This second stage is associated with a high energy hydrological environment.As there is a variability within the system, that is defined by changing water flow characteristics, there will be a compositional variability in exposure of so called ghost-endokarsts. Within the image and drawing attached the following areas are identified: 1. Fresh unweathered Limestone; 2. Stratified silt deposits; 3. Thin fluvial deposit with highly weathered quartz pebbles; 4. Remaining residual alterite resulting in ghost-rock karstification.It has been suggested that this process is far more widespread than has previously been known, and although most of the work has been carried out in Europe, it is a worldwide phenomena. So wherever you are on All Hallows Eve don’t be scared to think there could be a ghost rock right near you.RLImage credit: Keyhole at Gauthier–Wincqz Quarry in Soignies (Quinif et al., 1993).Reference: Dubois et al, The process of ghost-rock karstification and its role in the formation of cave systems, Earth-Science Reviews 131 (2014) 116–148 -- source link

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