Definition
“A line separating tracts of unglacierized terrain of strikingly different appearance, the appearance of one of the tracts being interpretable as due to recent deglaciation” (Cogley et al. 2011).
Formation
Trimlines record the most recent high-ice stands along the walls of glacial valleys, generally represented by a contrast in albedo above and below the trimline or as a contact between vegetated land above the trimline and bare surface below. Trimlines have also been used to identify mountains within glaciated terrain that escaped glacial erosion. These can represent unglaciated nunataks, standing proud of the ice surface, in which case the regional trimline represents the maximum surface elevation of the ice. Alternatively the trimline may represent an englacial boundary between warm-based (eroding) and cold-based (non-eroding) ice. The trimlines in the Scottish highlands are now regarded as marking an englacial thermal boundary because cosmogenic isotope exposure ages of...
This is a preview of subscription content, log in via an institution to check access.
References
Cogley JG, Hock R, Rasmussen LA, et al (2011) Glossary of glacier mass balance and related terms, IHP-VII technical documents in hydrology no. 86, IACS contribution no. 2, UNESCO-IHP, Paris
Dickson JL, Head JW, Marchant DR (2008) Late Amazonian glaciation at the dichotomy boundary on Mars: evidence for glacial thickness maxima and multiple glacial phases. Geology 36:411–414
Dickson JL, Head JW, Marchant DR (2010) Kilometer-thick ice accumulation and glaciation in the northern mid-latitudes of Mars: evidence for crater-filling events in the Late Amazonian at the Phlegra Montes. Earth Planet Sci Lett. doi:10.1016/j.epsl.2009.08.031
Fabel D, Ballantyne CK, Xu S (2012) Trimlines, blockfields, mountain-top erratics and the vertical dimensions of the last British-Irish Ice Sheet in NW Scotland. Quat Sci Rev. doi:10.1016/j.quascirev.2012.09.002
Gourronc M, Bourgeois O, Mege D, Pochat S, Bultel B, Massé M, Le Deit L, Le Mouélic S, Mercier D (2014) One million cubic kilometers of fossil ice in Valles Marineris: relicts of a 3.5 Gy old glacial landsystem along the Martian equator. Geomorphology 204:235–255
Mège D, Bourgeois O (2010) Destabilization of Valles Marineris wallslopes by retreat of ancient glaciers. 41st Lunar Planet Sci Conf, abstract #1713, Houston
Peulvast J-P, Mege D, Chiciak J, Costard F, Masson PL (2001) Morphology, evolution and tectonics of Valles Marineris wallslopes Mars. Geomorphology 37:329–352
Schultz RA (1991) Structural development of Coprates Chasma and Western Ophir Planum, Valles Marineris Rift, Mars. J Geophys Res 96(E5):22777–22792. doi:10.1029/91JE02556
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2014 Springer Science+Business Media New York
About this entry
Cite this entry
McCarroll, D. (2014). Trimline. In: Encyclopedia of Planetary Landforms. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-9213-9_383-1
Download citation
DOI: https://doi.org/10.1007/978-1-4614-9213-9_383-1
Received:
Accepted:
Published:
Publisher Name: Springer, New York, NY
Online ISBN: 978-1-4614-9213-9
eBook Packages: Springer Reference Earth and Environm. ScienceReference Module Physical and Materials ScienceReference Module Earth and Environmental Sciences