Moraine#End or terminal moraines

The word moraine is borrowed from French {{lang|fr|moraine}} {{IPA|fr|mɔ.ʁɛn|}}, which in turn is derived from the Savoyard Italian {{lang|it|morena}} ('mound of earth'). {{lang|it|Morena}} in this case was derived from Provençal {{lang|oc|morre}} ('snout'), itself from Vulgar Latin {{lang|la|*murrum}} ('rounded object').{{oed|moraine}} The term was introduced into geology by Horace Bénédict de Saussure in 1779.{{cite book |editor1-last=Jackson |editor1-first=Julia A. |title=Glossary of geology. |date=1997 |publisher=American Geological Institute |location=Alexandria, Virginia |isbn=0922152349 |edition=Fourth |chapter=moraine [glac geol]}}

Moraines are landforms composed of glacial till deposited primarily by glacial ice. Glacial till, in turn, is unstratified and unsorted debris ranging in size from silt-sized glacial flour to large boulders.{{sfn|Jackson|1997|loc="till"}} The individual rock fragments are typically sub-angular to rounded in shape.{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0131547283 |edition=4th |page=281}} Moraines may be found on the glacier's surface or deposited as piles or sheets of debris where the glacier has melted.{{sfn|Boggs|2006|pp=278-279}}

Moraines may form through a number of processes, depending on the characteristics of sediment, the dynamics on the ice, and the location on the glacier in which the moraine is formed.{{cite book |last1=Benn |first1=Douglas I. |last2=Evans |first2=David J.A. |title=Glaciers & glaciation |date=2010 |publisher=Routledge |location=London |isbn=978-0340905791 |edition=Second}} Moraine forming processes may be loosely divided into passive and active.{{cite journal |last1=Möller |first1=Per |title=Melt-out till and ribbed moraine formation, a case study from south Sweden |journal=Sedimentary Geology |date=December 2010 |volume=232 |issue=3–4 |pages=161–180 |doi=10.1016/j.sedgeo.2009.11.003|bibcode=2010SedG..232..161M }}

Passive processes involve the placing of chaotic supraglacial sediments onto the landscape with limited reworking, typically forming hummocky moraines.{{Cite journal|last1=Kjær|first1=Kurt H.|last2=Krüger|first2=Johannes|date=2001-10-21|title=The final phase of dead-ice moraine development: processes and sediment architecture, Kötlujökull, Iceland|journal=Sedimentology|language=en|volume=48|issue=5|pages=935–952|doi=10.1046/j.1365-3091.2001.00402.x|issn=1365-3091|bibcode=2001Sedim..48..935K|s2cid=129374153 }}{{cite journal |last1=Janowski |first1=Lukasz |last2=Tylmann |first2=Karol |last3=Trzcinska |first3=Karolina |last4=Rudowski |first4=Stanislaw |last5=Tegowski |first5=Jaroslaw |title=Exploration of Glacial Landforms by Object-Based Image Analysis and Spectral Parameters of Digital Elevation Model |journal=IEEE Transactions on Geoscience and Remote Sensing |date=2021 |volume=60 |pages=1–17 |doi=10.1109/TGRS.2021.3091771| issn=0196-2892|doi-access=free }} These moraines are composed of supraglacial sediments from the ice surface.

Active processes form or rework moraine sediment directly by the movement of ice, known as glaciotectonism. These form push moraines and thrust-block moraines, which are often composed of till and reworked proglacial sediment.{{Cite journal|last=Bennett|first=Matthew R.|date=2001-04-01|title=The morphology, structural evolution and significance of push moraines|journal=Earth-Science Reviews|volume=53|issue=3–4|pages=197–236|doi=10.1016/S0012-8252(00)00039-8|bibcode=2001ESRv...53..197B}}

Moraine may also form by the accumulation of sand and gravel deposits from glacial streams emanating from the ice margin. These fan deposits may coalesce to form a long moraine bank marking the ice margin.{{Cite journal|last=Boulton|first=G. S.|date=1986-10-01|title=Push-moraines and glacier-contact fans in marine and terrestrial environments|journal=Sedimentology|language=en|volume=33|issue=5|pages=677–698|doi=10.1111/j.1365-3091.1986.tb01969.x|issn=1365-3091|bibcode=1986Sedim..33..677B}} Several processes may combine to form and rework a single moraine, and most moraines record a continuum of processes. Reworking of moraines may lead to the formation of placer deposits of gold as is the case of southernmost Chile.{{Cite journal|title=Potential mineral resources of the Chilean offshore: an overview|journal=Andean Geology|url=http://www.andeangeology.cl/index.php/revista1/article/view/V47n1-3260/html|last1=García|first1=Marcelo|volume=47|pages=1–13|last2=Correa|first2=Jorge|issue=1|year=2020|last3=Maksaev|first3=Víctor|last4=Townley|first4=Brian|doi=10.5027/andgeoV47n1-3260|doi-access=free|bibcode=2020AndGe..47....1G }}

File:Ansel Adams - National Archives 79-AA-M02.jpg|Moraine in Rocky Mountain National Park, taken by Ansel Adams in 1941.

File:Icy-lake.jpg|Moraines around the Icy lake (2709 m), just below Musala peak (2925 m) in Rila Mountain, Bulgaria.

File:Moraines Surlej.jpg|Lateral moraines of a retreating glacier in Engadin.

File:Colline moreniche del Lago Garda.JPG|Moraine of Lake Garda.

{{See also|List of glacial moraines}}

{{More citations needed section|date=October 2021}}

Moraines can be classified either by origin, location with respect to a glacier or former glacier, or by shape.{{cite book |last1=Dreimanis |first1=Aleksis |editor1-last=Goldthwait |editor2-last=Matsch |title=Genetic classification of glacigenic deposits : final report of the Commission on Genesis and Lithology of Glacial Quaternary Deposits of the International Union for Quaternary Research (INQUA) |date=1989 |publisher=Balkema |location=Rotterdam |isbn=9061916941 |pages=17–83 |chapter=Tills: Their genetic terminology and classification}} {{cn span|date=November 2021|The first approach is suitable for moraines associated with contemporary glaciers—but more difficult to apply to old moraines, which are defined by their particular morphology, since their origin is debated. Some moraine types are known only from ancient glaciers, while medial moraines of valley glaciers are poorly preserved and difficult to distinguish after the retreat or melting of the glacier.}}

File:MorainesLakeLouise.JPG, Alberta, Canada.]]

Lateral moraines are parallel ridges of debris deposited along the sides of a glacier. The unconsolidated debris can be deposited on top of the glacier by frost shattering of the valley walls or from tributary streams flowing into the valley,{{Cite web|date=May 5, 2011|title=Lateral Moraine|url=https://www.nationalgeographic.org/encyclopedia/moraine/|access-date=June 18, 2020|website=National Geographic Encyclopedia}} or may be subglacial debris carried to the surface of the glacier, melted out, and transported to the glacier margin.{{cite journal |last1=Lukas |first1=Sven |last2=Graf |first2=Andreas |last3=Coray |first3=Sandro |last4=Schlüchter |first4=Christian |title=Genesis, stability and preservation potential of large lateral moraines of Alpine valley glaciers – towards a unifying theory based on Findelengletscher, Switzerland |journal=Quaternary Science Reviews |date=March 2012 |volume=38 |pages=27–48 |doi=10.1016/j.quascirev.2012.01.022|bibcode=2012QSRv...38...27L }}

File:Glacier.zermatt.arp.750pix.jpg, Zermatt, Switzerland. The lateral moraine is the high snow-free bank of debris in the top left hand quarter of the picture. The medial moraine is the double line of debris running down the centre-line of the glacier.]]

Lateral moraines can rise up to {{convert|140|m||sp=us}} over the valley floor, can be up to {{convert|3|km||sp=us}} long, and are steeper close to the glacier margin (up to 80 degrees) than further away (where slopes are typically 29 to 36 degrees).

File:Ground moraine 9004.jpg.]]

Ground moraines are till-covered areas with irregular topography and no ridges, often forming gently rolling hills or plains,{{sfn|Jackson|1997|loc="ground moraine"}} with relief of less than {{convert|10|m||sp=us}}. Ground moraine is accumulated at the base of the ice as lodgment till with a thin and discontinuous upper layer of supraglacial till deposited as the glacier retreats. It typically is found in the areas between end moraines.{{cite journal |last1=Hilt Johnson |first1=W. |last2=Menzies |first2=John |title=Supraglacial and ice-marginal deposits and landforms |journal=Modern and Past Glacial Environments |date=2002 |pages=317–333 |doi=10.1016/B978-075064226-2/50013-1|isbn=9780750642262 }}

{{Main|Rogen moraine}}

Rogen moraines or ribbed moraines are a type of basal moraines that form a series of ribs perpendicular to the ice flow in an ice sheet. The depressions between the ribs are sometimes filled with water, making the Rogen moraines look like tigerstripes on aerial photographs. Rogen moraines are named after Lake RogenMöller, P., 2006. Rogen moraine: an example of glacial reshaping of preexisting landforms. Quaternary Science Reviews, 25:362–389 in Härjedalen, Sweden, the landform's type locality.

Closely related to Rogen moraines, de Geer moraines are till ridges up to 5m high and 10–50m wide running perpendicular to the ice flow. They occur in large groups in low-lying areas.{{cite report |title = The Kvarken Archipelago |url = http://whc.unesco.org/uploads/nominations/898bis.pdf |author = Metsähallitus (Forest and Park Services) |date = 16 July 2006 |access-date = 3 October 2021}} Named for Gerard De Geer, who first described them in 1889, these moraines may have developed from crevasses underneath the ice sheet. The Kvarken has a very high density of de Geer moraines.{{cite journal |last1=Kotilainen |first1=Aarno T. |last2=Kaskela |first2=Anu M. |last3=Bäck |first3=Saara |last4=Leinikki |first4=Jouni |title=Submarine De Geer Moraines in the Kvarken Archipelago, the Baltic Sea |journal=Seafloor Geomorphology as Benthic Habitat |date=2012 |pages=289–298 |doi=10.1016/B978-0-12-385140-6.00017-7|isbn=9780123851406 }}

{{Main|Terminal moraine}}

Image:Erratics-Cascades-PB110028.JPG of the Okanogan Lobe. Cascade mountains in the background.]]

End moraines, or terminal moraines, are ridges of unconsolidated debris deposited at the snout or end of the glacier. They usually reflect the shape of the glacier's terminus. Glaciers act much like a conveyor belt, carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. End moraine size and shape are determined by whether the glacier is advancing, receding or at equilibrium. The longer the terminus of the glacier stays in one place, the more debris accumulate in the moraine. There are two types of end moraines: terminal and recessional. Terminal moraines mark the maximum advance of the glacier. Recessional moraines are small ridges left as a glacier pauses during its retreat. After a glacier retreats, the end moraine may be destroyed by postglacial erosion.{{cite book|author1=H.-E. Reineck|author2=I. B. Singh|title=Depositional Sedimentary Environments: With Reference to Terrigenous Clastics|url=https://books.google.com/books?id=UcjuCAAAQBAJ&pg=PA170|date=6 December 2012|publisher=Springer Science & Business Media|isbn=978-3-642-96291-2|pages=170–}}

Recessional moraines are often observed as a series of transverse ridges running across a valley behind a terminal moraine. They form perpendicular to the lateral moraines that they reside between and are composed of unconsolidated debris deposited by the glacier. They are created during temporary halts in a glacier's retreat."Moraine". Columbia Electronic Encyclopedia, 6th Edition (2009): 1. Academic Search Complete. EBSCO. Web. 6 Oct. 2010.

File:Ellesmere Island 04.jpg, Grant Land]]

In permafrost areas an advancing glacier may push up thick layers of frozen sediments at its front. An arctic push moraine will then be formed.

File:Nuussuaq-peninsula-moraines.jpg, Greenland.]]

A medial moraine is a ridge of moraine that runs down the center of a valley floor. It forms when two glaciers meet and the debris on the edges of the adjacent valley sides join and are carried on top of the enlarged glacier. As the glacier melts or retreats, the debris is deposited and a ridge down the middle of the valley floor is created. The Kaskawulsh Glacier in the Kluane National Park, Yukon, has a ridge of medial moraine 1 km wide.{{cite journal |last1=Loomis |first1=S.R. |year=1970 |title=Morphology and structure of an ice-cored medial moraine, Kaskawulsh Glacier, Yukon |journal=Arctic Institute of North America Research Paper |volume=57 |pages=1–65}}

{{wide image|Bruggen-PioXI FaceCompleteCroppedIMG5642.jpg|600px|align-cap=center|The prominent dark streak at the left quarter is forming a medial moraine.
This is seen as a mudflat at the water's surface. (Brüggen Glacier, Patagonia).}}

Supraglacial moraines are created by debris accumulated on top of glacial ice. This debris can accumulate due to ice flow toward the surface in the ablation zone,{{cite journal |last1=Boulton |first1=G. S. |title=The Development of a Complex Supraglacial Moraine at the Margin of Sørbreen, Ny Friesland, Vestspitsbergen |journal=Journal of Glaciology |date=1967 |volume=6 |issue=47 |pages=717–735 |doi=10.3189/S0022143000019961|s2cid=127729549 |doi-access=free }} melting of surface ice{{cite journal |last1=Fyffe |first1=Catriona L. |last2=Woodget |first2=Amy S. |last3=Kirkbride |first3=Martin P. |last4=Deline |first4=Philip |last5=Westoby |first5=Matthew J. |last6=Brock |first6=Ben W. |title=Processes at the margins of supraglacial debris cover: Quantifying dirty ice ablation and debris redistribution |journal=Earth Surface Processes and Landforms |date=August 2020 |volume=45 |issue=10 |pages=2272–2290 |doi=10.1002/esp.4879|bibcode=2020ESPL...45.2272F |s2cid=218998898 |doi-access=free }} or from debris that falls onto the glacier from valley sidewalls.{{cite journal |last1=Nakawo |first1=M. |last2=Iwata |first2=S. |last3=Watanabe |first3=O. |last4=Yoshida |first4=M. |title=Processes which Distribute Supraglacial Debris on the Khumbu Glacier, Nepal Himalaya |journal=Annals of Glaciology |date=1986 |volume=8 |pages=129–131 |doi=10.3189/S0260305500001294|bibcode=1986AnGla...8..129N |s2cid=246062157 |doi-access=free }}

Washboard moraines, also known as minor or corrugated moraines, are low-amplitude geomorphic features caused by glaciers. They consist of low-relief ridges, {{convert|1 to 2|m||sp=us}} in height and around {{convert|100|m||sp=us}} apart, accumulated at the base of the ice as lodgment till.{{cite journal |last1=Stewart |first1=Robert A. |last2=Bryant |first2=Deborah |last3=Sweat |first3=Michael J. |title=Nature and origin of corrugated ground moraine of the Des Moines lobe, Story County, Iowa |journal=Geomorphology |date=March 1988 |volume=1 |issue=2 |pages=111–130 |doi=10.1016/0169-555X(88)90010-4|bibcode=1988Geomo...1..111S }} The name "washboard moraine" refers to the fact that, from the air, it resembles a washboard.''

{{Main|Veiki moraine}}

A Veiki moraine is a kind of hummocky moraine that forms irregular landscapes of ponds and plateaus surrounded by banks. It forms from the irregular melting of ice covered with a thick layer of debris. Veiki moraine is common in northern Sweden and parts of Canada.

{{see also|List of glacial moraines}}

; Geologic features related to moraines

:* {{annotated link|Glacial landform}}

:* {{annotated link|Drumlin}}

:* {{annotated link|Esker}}

:* {{annotated link|Moraine-dammed lake}}

:* {{annotated link|Terminal moraine}}

:* {{annotated link|Rogen moraine}}

:* Kame

; Moraine examples

:* {{annotated link|Dogger Bank}}

:* {{annotated link|Kettle Moraine}}

:* {{annotated link|Long Island}}

:* {{annotated link|Oak Ridges Moraine}}

:* {{annotated link|Valparaiso Moraine}}

:* {{annotated link|Cypress Hills (Canada)}}

:* {{annotated link|Sleeping Bear Dunes National Lakeshore}}

{{Reflist}}

{{refbegin}}

• {{citation|last=Easterbrook |first=D. J. |year=1999 |title=Surface processes and landforms |edition=Second |location=Upper Saddle River, N.J. |publisher=Prentice Hall|isbn=9780138609580}}

{{refend}}

{{commons category|Moraines}}

{{wiktionary|moraine}}

• [https://web.archive.org/web/20160426164815/http://www.pantagraph.com/news/local/glacial-moraines-unmistakable-vestige-of-last-ice-age/article_78058029-8591-58f3-9bc6-9e5592cc3404.html "Glacial moraines unmistakable vestige of last ice age" – Pantagraph] (Bloomington, Illinois newspaper)

{{glaciers}}

{{sediment transport}}

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Category:Glaciology

Category:Sediments

Category:Geographical terminology in mountaineering

Category:Geomorphology

Category:Glacial landforms