Editing Moraine

{{Short description|Glacially formed accumulation of debris}}
{{About|geological phenomena|other uses|Moraine (disambiguation)}}
{{distinguish|text=[[Murrain]], an antiquated term for various infectious diseases affecting cattle and sheep}}
[[File:Manang site (54).JPG|thumb|right|250px|The snow-free debris hills around the lagoon are lateral and terminal moraines of a [[valley glacier]] in [[Manang]], Nepal.]]

A '''moraine''' is any accumulation of unconsolidated debris ([[regolith]] and [[Rock (geology)|rock]]), sometimes referred to as [[glacial till]], that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice sheet. It may consist of partly rounded particles ranging in size from boulders (in which case it is often referred to as boulder clay) down to gravel and sand, in a groundmass of finely-divided clayey material sometimes called [[glacial flour]]. Lateral moraines are those formed at the side of the ice flow, and [[terminal moraine]]s are those formed at the foot, marking the maximum advance of the glacier. Other types of moraine include ground moraines ([[till]]-covered areas forming sheets on flat or irregular [[topography]]) and medial moraines (moraines formed where two glaciers meet).

==Etymology==
The word ''moraine'' is borrowed from [[French language|French]] {{lang|fr|moraine}} {{IPA|fr|mɔ.ʁɛn|}}, which in turn is derived from the [[Savoyard dialect|Savoyard Italian]] {{lang|it|morena}} ('mound of earth'). {{lang|it|Morena}} in this case was derived from [[Provençal dialect|Provençal]] {{lang|oc|morre}} ('snout'), itself from [[Vulgar Latin]] {{lang|la|*murrum}} ('rounded object').<ref>{{oed|moraine}}</ref> The term was introduced into geology by [[Horace Bénédict de Saussure]] in 1779.<ref name=Jackson1997>{{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]}}</ref>

== Characteristics ==
Moraines are [[landforms]] composed of [[glacial till]] deposited primarily by glacial ice.<ref name=Jackson1997/> Glacial till, in turn, is [[Stratum|unstratified]] and [[Sorting (geology)|unsorted]] debris ranging in size from [[silt]]-sized [[Rock flour|glacial flour]] to large boulders.{{sfn|Jackson|1997|loc="till"}} The individual rock fragments are typically sub-angular to rounded in shape.<ref>{{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}}</ref> 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}}

=== Formation ===
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.<ref name="Benn & Evans">{{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}}</ref>  Moraine forming processes may be loosely divided into ''passive'' and ''active''.<ref name="Moller2010">{{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 }}</ref>

''Passive'' processes involve the placing of chaotic supraglacial sediments onto the landscape with limited reworking, typically forming [[hummock]]y moraines.<ref>{{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 }}</ref><ref>{{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 }}</ref>  These moraines are composed of supraglacial sediments from the ice surface.<ref name="Moller2010"/>

''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.<ref>{{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}}</ref>

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.<ref>{{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}}</ref> 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 deposit]]s of [[gold]] as is the case of [[Magallanes Region|southernmost Chile]].<ref>{{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 }}</ref>

<gallery widths="200" heights="160">
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|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]].
</gallery>

==Types of moraines==
{{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.<ref name="Dreimanis1989">{{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}}</ref> {{cn span|date=November 2021|The first approach is suitable for moraines associated with contemporary glaciers—but more difficult to apply to [[old moraine]]s, 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.}}

===Lateral moraines===
[[File:MorainesLakeLouise.JPG|thumb|Lateral moraines above [[Lake Louise (Alberta)|Lake Louise]], 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,<ref>{{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}}</ref> or may be subglacial debris carried to the surface of the glacier, melted out, and transported to the glacier margin.<ref name=LukasEtal2012>{{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 }}</ref>

[[File:Glacier.zermatt.arp.750pix.jpg|left|thumb|Moraines clearly seen on a side glacier of the [[Gorner Glacier]], 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).<ref name=LukasEtal2012/>

===Ground moraines===
[[File:Ground moraine 9004.jpg|thumb|Ground moraines create irregular, rolling topography near [[Gainesville, New York]].]]

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 [[Till#Types of till|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.<ref name=HiltJohnsonMenzies2002>{{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 }}</ref>

====Rogen moraines====
{{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 [[tigerstripe]]s on [[aerial photograph]]s. Rogen moraines are named after [[Lake Rogen]]<ref name=Moller>Möller, P., 2006. Rogen moraine: an example of glacial reshaping of preexisting landforms. ''[[Quaternary Science Reviews]]'', '''25''':362–389</ref> in [[Härjedalen]], [[Sweden]], the landform's type locality.

====de Geer moraines====
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.<ref name = "nominate">{{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}}</ref> Named for [[Gerard De Geer]], who first described them in 1889, these moraines may have developed from crevasses underneath the ice sheet.<ref name = "nominate"/> The [[Kvarken Archipelago|Kvarken]] has a very high density of de Geer moraines.<ref>{{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 }}</ref>

===End or terminal moraines===
{{Main|Terminal moraine}}
[[Image:Erratics-Cascades-PB110028.JPG|thumb|left|Multiple erratics on the [[Withrow Moraine and Jameson Lake Drumlin Field|Withrow terminal moraine]] of the Okanogan Lobe. Cascade mountains in the background.]]

End moraines, or [[terminal moraine]]s, are ridges of unconsolidated debris deposited at the snout or end of the glacier.  They usually reflect the shape of the [[Glacier terminus|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.<ref name="ReineckSingh2012">{{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–}}</ref>

===Recessional moraine===
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.<ref name="Benn & Evans"/><ref>"Moraine". ''Columbia Electronic Encyclopedia'', 6th Edition (2009): 1. Academic Search Complete. EBSCO. Web. 6 Oct. 2010.</ref>

===Arctic push moraines===
[[File:Ellesmere Island 04.jpg|thumb|Arctic push moraine in northern [[Ellesmere Island]], 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.

===Medial moraine===
[[File:Nuussuaq-peninsula-moraines.jpg|thumb|Medial moraines, [[Nuussuaq Peninsula]], [[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&nbsp;km wide.<ref>{{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}}</ref>

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

===Supraglacial moraines===
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]],<ref>{{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 }}</ref> melting of surface ice<ref>{{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 }}</ref> or from debris that falls onto the glacier from valley sidewalls.<ref>{{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 }}</ref>

===Washboard moraines===
[[Washboard moraine]]s, 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 [[Till#Types of till|lodgment till]].<ref>{{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 }}</ref> The name "washboard moraine" refers to the fact that, from the air, it resembles a [[washboard (laundry)|washboard]].''

===Veiki moraine===
{{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==
{{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}}

==References==
{{Reflist}}
{{refbegin}}

==Further reading==
* {{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}}

==External links==
{{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:Moraines| ]]
[[Category:Geographical terminology in mountaineering]]
[[Category:Geomorphology]]
[[Category:Glacial landforms]]