Pronival ramparts

Abstract

Pronival ramparts are debris ridges formed at the downslope margins of perennial or semi-permanent snowbeds beneath bedrock cliffs. These landforms, also previously known as protalus ramparts, are located in periglacial environments, but the apparent simplicity of rampart formation made these landforms far less interesting than other modified forms of talus in cold environments. As a result, limited research, use of supposed relict examples and assumed formative mechanisms led to the misidentification of ramparts, circular arguments regarding genesis and inappropriate palaeo-environmental inferences. Several advances have, however, been made in the past few decades, particularly where actively-forming ramparts have been studied. Thus, this paper provides a review of research on pronival ramparts. In particular, focus is placed on the advances made in our understanding of rampart genesis, identification (diagnostic criteria) and palaeo-environmental significance. Notable advances include the development of a retrogressive model of rampart genesis to supplement the conventional downslope model of development, revised diagnostic criteria for field identification and the use of calibration equations during Schmidt-hammer exposure dating of pronival rampart. The use of pronival ramparts as palaeo-environmental indicators is also examined to determine what relict examples of these landforms may reveal about past climates.

Late Pleistocene glaciers to present-day snowpatches: a review and research recommendations for the Marrakech High Atlas

“…Future work will also involve a detailed mapping of these high-level sites. Differentiating between moraines and pronival ramparts is often difficult (Hedding 2016) in the same way that late-lying snowpatches are difficult to differentiate from glacierets (Cogley et al 2011). However, this has already been achieved for some sediment ridges on the basis of detailed geomorphological mapping and sedimentological characteristics (e.g.…”

“…In the Atlas Mountains, most of these records have been obtained in the Middle Atlas, with numerous publications documenting pollen and other proxies for environmental change through the Late Pleistocene and Holocene (e.g. Lamb et al 1989Lamb et al , 1999Barker and Roberts 1994;Cheddadi et al 1998Cheddadi et al , 2019Rhoujjati et al 2010;Nour el Bait et al 2014, 2016Tabel et al 2016;Campbell et al 2017;. However, equivalent records from the High Atlas are less common.…”

Identifying and mapping very small (<0.5 km2) mountain glaciers on coarse to high-resolution imagery

“…Therefore, lack of convexity of a snowpatch does not remove the possibility of buried glacier ice. However, consideration should be made of the incorrect interpretation of snow and associated moraine-like ridges, as it is possible they are periglacial features such as pronival ramparts (Hedding, 2016 a ). Pronival ramparts form at the base of perennial snowpatches and are not glacial in origin (Shakesby, 1997; Hedding and Sumner, 2013; Hedding, 2016 b ).…”

Contextualizing lobate debris aprons and glacier-like forms on Mars with debris-covered glaciers on Earth

“…Forms related to rock glaciers include multi-lobate rock glaciers (Degenhardt, 2009), piedmont or spatulate rock glaciers based on their unbounded terminus form, as well as pronival ramparts and protalus ramparts (e.g. Hedding, 2016). A pronival rampart is a ridge (or series of ridges) at the base of a cliff that has been sourced by upslope debris and snow, and is a depositional periglacial landform.…”