Multiple talus flatirons, variations of scarp retreat rates and the evolution of slopes in Almazán Basin (semi-arid central Spain)

Considerations on the chronological and causal relationships between talus flatirons and palaeoclimatic changes in central and northeastern Spain

“…5A and 7). The deposits of three paleoslopes have been dated with AMS radiocarbon (Gutiérrez-Elorza and Sesé, 2001). The abundance of talus flatirons in this area is mainly propitiated by the lithostratigraphy, composed of a scarp-forming limestone unit 5-8 m thick, overlying a thick sequence of shales, which favours scarp retreat and tripartite slope generation.…”

“…There is a generalized consensus about the climatic origin of the incision-accumulation periods responsible for the generation of flatirons (Everard, 1963;Gerson, 1982;Gerson and Grossman, 1987;Sancho et al, 1988;Gutiérrez-Elorza et al, 1998a,b;Schmidt, 1989aSchmidt, ,b, 1994Schmidt, , 1996Gutiérrez-Elorza and Sesé, 2001). The absolute ages of sequences of talus flatirons would, therefore, contribute towards deciphering their morpho-climatological dependence.…”

Origin and evolution of playas and blowouts in the semiarid zone of Tierra de Pinares (Duero Basin, Spain)

“…This switch in the morphogenetic processes is related to climate change. Accumulation processes prevail during cold periods, whereas incision dominates in relatively warm periods (Gutiérrez Elorza and Sesé, 2001). Regardless of their age, the convex-concave slope profiles and the triangular slope facets reveal that the area has been subjected to at least one cold period in which the climate has determined the geomorphic processes.…”

Slope Systems

“…Parsons et al (2006) provided empirical support for this interpretation for slopes at Walnut Gulch in Arizona. Rates of talus flatiron development have been studied by Gutiérrez et al (1998) and Gutiérrez Elorza and Sesé Martinez (2001), who studied the rates of slope evolution under flatirons in the Ebro and Almazán Basins in Northern Spain. They concluded that scarp retreat rates were of the order of 1-10 mm/a and corresponded well with changes in climate over the last 30,000 years.…”

“…In certain locations, such as the semi-arid southwestern USA (Schmidt and Meitz, 1996) and Northern Spain (Gutiérrez et al, 1998(Gutiérrez et al, , 2001, it is clear that talus slopes are currently evolving at significant rates, particularly during periods of enhanced rainfall. During drier periods, or in drier locations, flatirons tend to become disconnected from the adjacent supply of caprock material and will dissect, until bare rock substrates are exposed.…”