Depositional facies of accumulated rock-debris below a limestone cliff, in the English Lake District, hold clues to environment change since deglaciation. Glacifluvial talus is a deglacial accumulation of compact sub-rounded glacifluvial cobbles and boulders, with an admixture of angular cliff-fall boulders. Scree is a less-compact, openwork, likely Younger Dryas, accumulation of angular cliff-fall rock fragments that overlies the talus. Both facies were subject to precipitation of calcite cement along preferential drainage lines. Scanning electron microscopy showed that the talus is weakly micrite-cemented, averring for largely phreatic, formerly higher, groundwater conditions at the cliff base, whilst hard, sparry-cement within the scree indicates vadose drainage behind the scree down the cliff face. The cement primarily is calcite (< 97.9%) and dolomite (< 1.5%) with an important but highly variable admixture of quartz (< 30%); the latter derived, in part, from glacial-transported lithologies but primarily from windblown material. The latter is locally-abundant, occurring as an uncalcified sandy-matrix within the scree due to infiltration deposition of locally-sourced coversand and loess. Oxygen isotope (δ 18 O) values indicate that calcite cementation is due to input of meteoric waters at July air temperatures of between 8.3 and 15.5 °C, whilst carbon isotope (δ 13 C) values indicate a low presence of organic material. The isotopes conjointly indicate a warming climate (probably following the Younger Dryas) where microbial respiration, rather than strong terrestrial carbon inputs, mediated cementation. There are no stratigraphical indicators within the scree to indicate any variation in the climatic drivers of the weathering process that followed deglaciation until today.
Carling et al. (Sun,) studied this question.