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A glacial erratic is glacially deposited
rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...
differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by
glacial ice A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large
boulders In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In c ...
such as Big Rock () in
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Terri ...
. Geologists identify erratics by studying the rocks surrounding the position of the erratic and the composition of the erratic itself. Erratics are significant because: *They can be transported by glaciers, and they are thereby one of a series of indicators which mark the path of prehistoric glacier movement. Their lithographic origin can be traced to the parent
bedrock In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bedro ...
, allowing for confirmation of the ice flow route. *They can be transported by
ice rafting Ice rafting is the transport of various materials by ice. Various objects deposited on ice may eventually become embedded in the ice. When the ice melts after a certain amount of drifting, these objects are deposited onto the bottom of the water ...
. This allows quantification of the extent of glacial flooding resulting from ice dam failure which release the waters stored in
proglacial lake In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around th ...
s such as Lake Missoula. Erratics released by ice-rafts that were stranded and subsequently melted, dropping their load, allow characterization of the high-water marks for transient floods in areas like temporary
Lake Lewis Lake Lewis was a temporary lake in the Pacific Northwest region of North America, largely formed by the Missoula Floods in about the 14th millennium B.C. Lake Lewis was formed when the restricted flow of waters from periodic cataclysmic floods f ...
. *Erratics dropped by icebergs melting in the ocean can be used to track
Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...
and Arctic-region glacial movements for periods prior to record retention. Also known as
dropstone Dropstones are isolated fragments of rock found within finer-grained water-deposited sedimentary rocks or pyroclastic beds. They range in size from small pebbles to boulders. The critical distinguishing feature is that there is evidence that the ...
s, these can be correlated with ocean temperatures and levels to better understand and calibrate models of the global climate.


Formation of erratics

The term "erratic" is commonly used to refer to erratic blocks, which geologist
Archibald Geikie Sir Archibald Geikie (28 December 183510 November 1924) was a Scottish geologist and writer. Early life Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. T ...
describes as: "large masses of rock, often as big as a house, that have been transported by glacier-ice, and have been lodged in a prominent position in the glacier valleys or have been scattered over hills and plains. And examination of their mineralogical character leads the identification of their sources…". In geology, an erratic is material moved by geologic forces from one location to another, usually by a glacier. Erratics are formed by glacial ice erosion resulting from the movement of ice. Glaciers erode by multiple processes: abrasion/scouring, plucking, ice thrusting and glacially-induced spalling. Glaciers crack pieces of bedrock off in the process of plucking, producing the larger erratics. In an abrasion process, debris in the basal ice scrapes along the bed, polishing and gouging the underlying rocks, similar to sandpaper on wood, producing smaller glacial till. In ice thrusting, the glacier freezes to its bed, then as it surges forward, it moves large sheets of frozen sediment at the base along with the glacier. Glacially induced spalling occurs when
ice lens Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable ...
formation with the rocks below the glacier spall off layers of rock, providing smaller debris which is ground into the glacial basal material to become till. Evidence supports another option for creation of erratics as well, rock avalanches onto the upper surface of the glacier ( supraglacial). Rock
avalanche An avalanche is a rapid flow of snow down a slope, such as a hill or mountain. Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and eart ...
supraglacial transport occurs when the glacier undercuts a rock face, which fails by avalanche onto the upper surface of the glacier. The characteristics of rock
avalanche An avalanche is a rapid flow of snow down a slope, such as a hill or mountain. Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and eart ...
supraglacial transport includes: :*Monolithologic composition – a cluster of boulders of similar composition are frequently found in close proximity. Commingling of the multiple
lithologies The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lith ...
normally present throughout the glaciated basin, has not occurred. :*Angularity – the supraglacially transported rocks tend to be rough and irregular, with no sign of subglacial abrasion. The sides of boulders are roughly planar, suggesting that some surfaces may be original fracture planes. :*Great size – the size distribution of the boulders tends to be skewed toward larger boulders than those produced subglacially. :*Surficial positioning of the boulders – the boulders are positioned on the surface of glacial deposits, as opposed to partially or totally buried. :*Restricted areal extents – the boulder fields tend to have limited areal extent; the boulders cluster together, consistent with the boulders landing on the surface of the glacier and subsequently deposited on top of the glacial drift. :*Orientations – the boulders may be close enough that original fracture planes can be matched. :*Locations of the boulder trains – the boulders appear in rows, trains or clusters along the lateral moraines as opposed to being located on the
terminal moraine A terminal moraine, also called end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge ...
or in the general glacial field.


Glacier-borne erratic

Erratics provide an important tool in characterizing the directions of glacier flows, which are routinely reconstructed used on a combination of
moraine A moraine is any accumulation of unconsolidated debris (regolith and 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 she ...
s,
esker An esker, eskar, eschar, or os, sometimes called an ''asar'', ''osar'', or ''serpent kame'', is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North Ame ...
s, drumlins,
meltwater Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be ...
channels, and similar data. Erratic distributions and glacial till properties allow for identification of the source rock from which they derive, which confirms the flow direction, particularly when the erratic source outcrop is unique to a limited locality. Erratic materials may be transported by multiple glacier flows prior to their deposition, which can complicate the reconstruction of the glacial flow.


Ice-rafted erratic

Glacial ice entrains debris of varying sizes from small particles to extremely large masses of rock. This debris is transported to the coast by glacier ice and released during the production, drift and melting of icebergs. The rate of debris release by ice depends upon the size of the ice mass in which it is carried as well as the temperature of the ocean through which the ice floe passes. Sediments from the late
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
period lying on the floor of the
North Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...
show a series of layers (referred to as Heinrich layers) which contain
ice-rafted debris Ice rafting is the transport of various materials by ice. Various objects deposited on ice may eventually become embedded in the ice. When the ice melts after a certain amount of drifting, these objects are deposited onto the bottom of the water ...
. They were formed between 14,000 and 70,000 years before the present. The deposited debris can be traced back to the origin by both the nature of the materials released and the continuous path of debris release. Some paths extend more than distant from the point at which the ice floes originally broke free. The location and altitude of ice-rafted boulders relative to the modern landscape has been used to identify the highest level of water in proglacial lakes (e.g. Lake Musselshell in central
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Colum ...
) and temporary lakes (e.g.
Lake Lewis Lake Lewis was a temporary lake in the Pacific Northwest region of North America, largely formed by the Missoula Floods in about the 14th millennium B.C. Lake Lewis was formed when the restricted flow of waters from periodic cataclysmic floods f ...
in
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
state). Ice-rafted debris is deposited when the iceberg strands on the shore and subsequently melts, or drops out of the ice floe as it melts. Hence all erratic deposits are deposited below the actual high water level of the lake; however the measured altitude of ice-rafted debris can be used to estimate the lake surface elevation. This is accomplished by recognizing that on a fresh-water lake, the iceberg floats until the volume of its ice-rafted debris exceeds 5% of the volume of the iceberg. Therefore, a correlation between the iceberg size and the boulder size can be established. For example, a boulder can be carried by a iceberg and could be found stranded at higher elevations than a boulder, which requires a iceberg.


Large erratics

Large erratics consisting of slabs of bedrock that have been lifted and transported by glacier ice to subsequently be stranded above thin glacial or
fluvioglacial deposits Glaciofluvial deposits or Glacio-fluvial sediments consist of boulders, gravel, sand, silt and clay from ice sheets or glaciers. They are transported, sorted and deposited by streams of water. The deposits are formed beside, below or downstream ...
are referred to as glacial floes, rafts (schollen) or erratic megablocks. Erratic megablocks have typical length to thickness ratios on the order of 100 to 1. These megablocks may be found partially exposed or completely buried by till and are clearly
allochthon upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a nappe. If an erosional hole is created in the nappe that is called a window (geology)">window. A klippe is a solitary ou ...
ous, since they overlay glacial till. Megablocks can be so large that they are mistaken for bedrock until underlying glacial or fluvial sediments are identified by drilling or excavation. Such erratic megablocks greater than in area and in thickness can be found on the
Canadian Prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
, England, Denmark and
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
. One erratic megablock located in
Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...
is (and up to thick). Their sources can be identified by locating the bedrock from which they were separated; several rafts from Poland and Alberta were determined to have been transported over from their source.


Nonglacial erratics

In geology an erratic is any material which is not native to the immediate locale but has been transported from elsewhere. The most common examples of erratics are associated with glacial transport, either by direct glacier-borne transport or by ice rafting. However, other erratics have been identified as the result of
kelp Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms. Kelp grows in "underwat ...
holdfasts, which have been documented to transport rocks up to in diameter, rocks entangled in the roots of drifting logs, and even in transport of stones accumulated in the stomachs of
pinniped Pinnipeds (pronounced ), commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae (whose only living member is the walr ...
s during foraging.


History

During the 18th century, erratics were deemed a major geological paradox. Geologists identify erratics by studying the rocks surrounding the position of the erratic and the rock of the erratic itself. Erratics were once considered evidence of a biblical flood, but in the 19th Century scientists gradually came to accept that erratics pointed to an ice age in Earth's past. Among others, the
Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places * Swiss, Missouri * Swiss, North Carolina *Swiss, West Virginia * Swiss, Wisconsin Other uses *Swiss-system tournament, in various games and sports *Swiss Internationa ...
politician A politician is a person active in party politics, or a person holding or seeking an elected office in government. Politicians propose, support, reject and create laws that govern the land and by an extension of its people. Broadly speaking, a ...
, jurist and theologian saw glaciers as a possible solution as early as 1788. However the idea of ice ages and glaciation as a geological force took a while to be accepted.
Ignaz Venetz Ignaz (Ignace) Venetz (1788 — 1859) was a Swiss engineer, naturalist, and glaciologist; as one of the first scientists to recognize glaciers as a major force in shaping the earth, he played a leading role in the foundation of glaciology. B ...
(1788–1859), a Swiss engineer, naturalist, and
glaciologist Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, clim ...
was one of the first scientists to recognize glaciers as a major force in shaping the earth. In the 19th century, many scientists came to favor erratics as evidence for the end of the Last Glacial Maximum ( ice age) 10,000 years ago, rather than a flood.
Geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, alth ...
s have suggested that landslides or rockfalls initially dropped the rocks on top of glacial ice. The glaciers continued to move, carrying the rocks with them. When the ice melted, the erratics were left in their present locations.
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
's ''
Principles of Geology ''Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation'' is a book by the Scottish geologist Charles Lyell that was first published in 3 volumes from 1830–1833. Ly ...
'' (v. 1, 1830) provided an early description of the erratic which is consistent with the modern understanding.
Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he rec ...
was the first to scientifically propose that the Earth had been subject to a past ice age.E.P. Evans:
The Authorship of the Glacial Theory
, ''North American review'' Volume 145, Issue 368, July 1887. Accessed on February 25, 2008.
In the same year, he was elected a foreign member of the
Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for prom ...
. Prior to this proposal,
Goethe Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German poet, playwright, novelist, scientist, statesman, theatre director, and critic. His works include plays, poetry, literature, and aesthetic criticism, as well as tre ...
, de Saussure, Venetz, Jean de Charpentier, Karl Friedrich Schimper and others had made the glaciers of the
Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...
the subjects of special study, and Goethe, Charpentier as well as Schimper had even arrived at the conclusion that the erratic blocks of alpine rocks scattered over the slopes and summits of the Jura Mountains had been moved there by glaciers.
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
published extensively on geologic phenomena including the distribution of erratic boulders. In his accounts written during the voyage of , Darwin observed a number of large erratic boulders of notable size south of the
Strait of Magellan The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and Tierra del Fuego to the south. The strait is considered the most important natural pas ...
,
Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...
and attributed them to ice rafting from
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. Recent research suggests that they are more likely the result of glacial ice flows carrying the boulders to their current locations.


Examples


Glacier-borne erratics


Australia

* Exhumed erratics eroded from unconsolidated 270 Ma
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
glacial sediments can be found on the beach and in the park at Hallett Cove Conservation Park just south of
Adelaide Adelaide ( ) is the capital city of South Australia, the state's largest city and the fifth-most populous city in Australia. "Adelaide" may refer to either Greater Adelaide (including the Adelaide Hills) or the Adelaide city centre. The dem ...
, and in other South Australian locations, such as Inman Valley.


Canada

* Big Rock near
Okotoks Okotoks (, originally ) is a town in the Calgary Region of Alberta, Canada. It is on the Sheep River, approximately south of Calgary. Okotoks has emerged as a bedroom community of Calgary. According to the 2016 Census, the town has a population ...
,
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Terri ...
, Canada. It is the largest erratic in the Foothills Erratics Train. * Bleasdell Boulder, southern
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
was described as "glacial" in origin by Reverend William Bleasdell in 1872 * The Foothills Erratics Train is a deposit of rocks of many sizes. These deposits stretch in a narrow belt for about from
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Terri ...
's
Athabasca River The Athabasca River (French: ''Rivière Athabasca'') is a river in Alberta, Canada, which originates at the Columbia Icefield in Jasper National Park and flows more than before emptying into Lake Athabasca. Much of the land along its banks is pro ...
Valley to the southwest of the
province A province is almost always an administrative division within a country or state. The term derives from the ancient Roman ''provincia'', which was the major territorial and administrative unit of the Roman Empire's territorial possessions outsi ...
. *
White Rock, British Columbia White Rock is a city in British Columbia, Canada, and a member municipality of the Metro Vancouver Regional District. It borders Semiahmoo Bay to the south and is surrounded on three sides by Surrey. To the southeast across a footbridge lies the ...
gets its name from a coastal erratic the size of a garage found on the beach at
Semiahmoo Bay Semiahmoo Bay ( ) is the southeastern section of Boundary Bay on the Pacific coast of North America. The bay is named for the Semiahmoo First Nation, who originally occupied the area. The Semiahmoo Peninsula borders the bay and was home to canner ...
, right at the border with
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
. *Boulder i
Green Timbers Urban Forest
in
Surrey Surrey () is a ceremonial and non-metropolitan county in South East England, bordering Greater London to the south west. Surrey has a large rural area, and several significant urban areas which form part of the Greater London Built-up Area. W ...
, British Columbia, described as a glacial erratic on th
city website
img title="Erratic"; style="text-decoration: none; height:150px;float: left; padding: 0px 3px 0px 0px;"src="https://upload.wikimedia.org/wikipedia/commons/1/1c/Erratic.jpg" >


Estonia

* Ehalkivi (Sunset Glow Boulder) near Letipea, Estonia is the largest erratic boulder in the glaciation area of North Europe. Height 7 m, circumference 48.2 m, a volume of 930 m3 and a mass of approx 2500 tonnes.


Finland

* Kukkarokivi, located close to
Turku Turku ( ; ; sv, Åbo, ) is a city and former capital on the southwest coast of Finland at the mouth of the Aura River, in the region of Finland Proper (''Varsinais-Suomi'') and the former Turku and Pori Province (''Turun ja Porin lääni''; 1 ...
at the Ruissalo island in
Southwest Finland Southwest Finland, calqued as Finland Proper ( fi, Varsinais-Suomi ; sv, Egentliga Finland), is a region in the southwest of Finland. It borders the regions of Satakunta, Pirkanmaa, Tavastia Proper (Kanta-Häme), Uusimaa, and Åland. The reg ...
. It is the largest in Finland; length about 40 m, width about 30 m, height 12 m, weight about 36,000 tonnes.


Germany

* Colossus of Ostermunzel, Lower Saxony * Der Alte Schwede, found during dredging of the river Elbe near Hamburg in 1999; oldest in Germany. *
Giebichenstein The Giebichenstein in Stöckse, Germany, is one of the largest erratic boulders of northern Germany. It is in a city called Landkreis Nienburg/Weser. It weighs around 330 tons. A picture of the Giebichenstein is part of the emblem of the Stöck ...
,
Stöckse Stöckse is a municipality in the district of Nienburg, in Lower Saxony, Germany. It is situated in the forest "Krähe" between Langendamm and Steimbke. Policy Municipality Stöckse The villages Stöckse and Wenden with district L ...
, Lower Saxony * Glacial erratics on and around Rügen


Republic of Ireland

* The Clonfinlough Stone, located in central Ireland, is covered with
Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
and
medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
carvings.


Latvia

* Nīcgale Great Stone, located in
Nīcgale Parish Nīcgale Parish ( lv, Nīcgales pagasts; ltg, Neicgaļa pogosts) is an administrative unit of Augšdaugava Municipality in the Latgale region of Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic ...
. * Brodu quarry stone, located in
Jēkabpils Jēkabpils (; german: Jakobstadt; pl, Jakubów) is a state city in Jēkabpils Municipality in southeastern Latvia roughly halfway between Riga and Daugavpils and spanning the Daugava River. Historic Jēkabpils lies on the left bank, in Seloni ...
. * Lauču stone, located in Lauči,
Skulte parish Skulte Parish ( lv, Skultes pagasts) is an administrative unit of Limbaži Municipality, Latvia. It was an administrative unit of Limbaži District Limbaži District ( lv, Limbažu rajons) was an administrative division of Latvia, located in ...
, Limbaži municipality. Believed to have separated from a glacier in the
Vyborg Vyborg (; rus, Вы́борг, links=1, r=Výborg, p=ˈvɨbərk; fi, Viipuri ; sv, Viborg ; german: Wiborg ) is a town in, and the administrative center of, Vyborgsky District in Leningrad Oblast, Russia. It lies on the Karelian Isthmus n ...
area of
Southern Finland Southern Finland ( fi, Etelä-Suomen lääni, sv, Södra Finlands län) was a province of Finland from 1997 to 2009. It bordered the provinces of Western Finland and Eastern Finland. It also bordered the Gulf of Finland and Russia. History O ...
and Russia.


Lithuania

* Puntukas, one of national symbols of Lithuania, near Anykščiai city.


Poland

* Trygław, Tychowo * Devil Stone, Kashubia


United Kingdom


=England

= * The Crosby Erratic, Coronation Park, Liverpool, England; unearthed in a field nearby in 1898. * The Great Stone of Fourstones, at the county boundary between
North Yorkshire North Yorkshire is the largest ceremonial county (lieutenancy area) in England, covering an area of . Around 40% of the county is covered by national parks, including most of the Yorkshire Dales and the North York Moors. It is one of four cou ...
and Lancashire, has fifteen steps carved in its side to enable it to be climbed. * The Hitching Stone in
North Yorkshire North Yorkshire is the largest ceremonial county (lieutenancy area) in England, covering an area of . Around 40% of the county is covered by national parks, including most of the Yorkshire Dales and the North York Moors. It is one of four cou ...
. It is the largest erratic block in the county. * The Merton Stone, Merton,
Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the North ...
. * The
Norber erratics The Norber erratics are one of the finest groups of glacial erratic boulders in Britain. They are found on the southern slopes of Ingleborough, close to the village of Austwick in the Yorkshire Dales. The Ordnance Survey grid reference of the b ...
in the
Yorkshire Dales The Yorkshire Dales is an upland area of the Pennines in the historic county of Yorkshire, England, most of it in the Yorkshire Dales National Park created in 1954. The Dales comprise river valleys and the hills rising from the Vale of York ...
are one of England's finest sets of glacial erratics. * Soulbury Stone, located in
Soulbury Soulbury is a village and also a civil parish within the unitary authority area of Buckinghamshire, England. It is located in the Aylesbury Vale, about seven miles south of Central Milton Keynes, and three miles north of Wing. The village na ...
,
Buckinghamshire Buckinghamshire (), abbreviated Bucks, is a ceremonial county in South East England that borders Greater London to the south-east, Berkshire to the south, Oxfordshire to the west, Northamptonshire to the north, Bedfordshire to the north-east ...
.


=Scotland

= * Jim Crow Rock, glacial erratic in
Hunters Quay Hunters Quay ( gd, Camas Rainich) is a village, on the Cowal peninsula in Argyll and Bute, Scottish Highlands. Situated between Kirn to the south and Ardnadam to the north, Hunters Quay is the main base of Western Ferries, operating between Hu ...
, situated on the foreshore of the
Firth of Clyde The Firth of Clyde is the mouth of the River Clyde. It is located on the west coast of Scotland and constitutes the deepest coastal waters in the British Isles (it is 164 metres deep at its deepest). The firth is sheltered from the Atlantic ...
. The rock has been the subject of controversy because of an allegedly racist face painted on it.


=Northern Ireland

= * Cloughmore, near
Rostrevor Rostrevor () is a village and townland in County Down, Northern Ireland. It lies at the foot of Slieve Martin on the coast of Carlingford Lough, near Warrenpoint. The Kilbroney River flows through the village and Rostrevor Forest is nearby ...
in
County Down County Down () is one of the six counties of Northern Ireland, one of the nine counties of Ulster and one of the traditional thirty-two counties of Ireland. It covers an area of and has a population of 531,665. It borders County Antrim to th ...
,
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...
, is a glacial erratic found on the mountain high above the village. Located on the slopes of Slieve Martin, the stone overlooks
Carlingford Lough Carlingford Lough (, Ulster Scots: ''Carlinford Loch'') is a glacial fjord or sea inlet in northeastern Ireland, forming part of the border between Northern Ireland to the north and the Republic of Ireland to the south. On its northern shore is ...
and the
Cooley peninsula The Cooley Peninsula (, older ''Cúalṅge'') is a hilly peninsula in the north of County Louth on the east coast of Ireland; the peninsula includes the small town of Carlingford, the port of Greenore and the village of Omeath. Geography Th ...
.


United States

* Bubble Rock, perched on the edge of a cliff near the summit of South Bubble mountain in
Acadia National Park Acadia National Park is an American national park located along the mid-section of the Maine coast, southwest of Bar Harbor. The park preserves about half of Mount Desert Island, part of the Isle au Haut, the tip of the Schoodic Peninsula, an ...
, Maine. * Doane Rock, the largest exposed boulder in
Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...
, Massachusetts. *
Fantastic Erratic Glacial erratic boulders of King County are large glacial erratic boulders of rock which were moved into King County, Washington by glacial action during previous ice ages. The Pleistocene ice age glaciation of Puget Sound created many of th ...
, a fern-covered erratic the size of a two-car garage, is found on
Cougar Mountain Cougar Mountain is a peak in the Issaquah Alps in King County, Washington. It is part of the highlands in the Eastside suburbs of Seattle, and at it is the lowest and westernmost of the Alps. About two-thirds of Cougar Mountain has experience ...
near
Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest region of ...
. * Glen Rock, a boulder weighing in Glen Rock, New Jersey, believed to have been carried to the site by a glacier that picked up the rock 15,000 years ago near
Peekskill, New York Peekskill is a city in northwestern Westchester County, New York, United States, from New York City. Established as a village in 1816, it was incorporated as a city in 1940. It lies on a bay along the east side of the Hudson River, across from ...
. * Indian Rock in
Montebello, New York Montebello (Italian: "beautiful mountain") is an incorporated village in Ramapo, Rockland County, New York, United States. It is located north of Suffern, east of Hillburn, south of Wesley Hills, and west of Airmont. The population was 4,526 ...
is a large glacial erratic boulder of granite gneiss, formed in the Proterozoic (Precambrian) era, 1.2 billion to 800 million years ago. It is estimated to weigh ≈17,300 tons. * Madison Boulder, a glacial erratic the size of a large house in
Madison, New Hampshire Madison is a town in Carroll County, New Hampshire, United States. The population was 2,565 at the 2020 census. Madison includes the village of Silver Lake and the village district of Eidelweiss. History The area was one of the first to have ...
. *
Olmsted Point Olmsted Point is a viewing area off Tioga Pass Road in Yosemite National Park which offers a view south into Tenaya Canyon, giving, in particular, a view of the northern side of Half Dome, Clouds Rest, and a view of Tenaya Lake to the east. The g ...
in
Yosemite National Park Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an a ...
is noteworthy for having granite hills covered in numerous small glacial erratics. *
Plymouth Rock Plymouth Rock is the traditional site of disembarkation of William Bradford and the ''Mayflower'' Pilgrims who founded Plymouth Colony in December 1620. The Pilgrims did not refer to Plymouth Rock in any of their writings; the first known writ ...
, the site in
Plymouth, Massachusetts Plymouth (; historically known as Plimouth and Plimoth) is a town in Plymouth County, Massachusetts, United States. Located in Greater Boston, the town holds a place of great prominence in American history, folklore, and culture, and is known as ...
on which the ''
Mayflower ''Mayflower'' was an English ship that transported a group of English families, known today as the Pilgrims, from England to the New World in 1620. After a grueling 10 weeks at sea, ''Mayflower'', with 102 passengers and a crew of about 30, r ...
'' Pilgrims landed in 1620. It is an important symbol in American history. * Rollstone Boulder, a 110-ton porphyritic granite boulder that was originally located at the summit of Rollstone Hill in
Fitchburg, Massachusetts Fitchburg is a city in northern Worcester County, Massachusetts, United States. The third-largest city in the county, its population was 41,946 at the 2020 census. Fitchburg is home to Fitchburg State University as well as 17 public and private ...
. It was carried by the last glaciation from central
New Hampshire New Hampshire is a state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec to the north. ...
. Threatened by quarrying operations, it was moved to Litchfield Park in downtown Fitchburg in 1929-1930. * The northern portion of the town of
Waterville, Washington Waterville is a town in and the county seat of Douglas County, Washington, United States which is known for its wheat industry. As a part of Douglas County, it is part of the Wenatchee-East Wenatchee metropolitan area. The population was 1,134 ...
has a large number of large basalt erratics, particularly along the moraine running east–west from McNeil Canyon. * Tripod Rock in
Kinnelon, New Jersey Kinnelon () is a borough in Morris County, New Jersey, United States, located approximately west of New York City. As of the 2020 United States census, the borough's population was 9,966, a drop of 282 (-2.8%) from the 2010 census count of 1 ...
is noteworthy for being perched on three smaller boulders. * Balance Rock in
Princeton, Massachusetts Princeton is a town in Worcester County, Massachusetts, United States. It is bordered on the east by Sterling and Leominster, on the north by Westminster, on the northwest by Hubbardston, on the southwest by Rutland, and on the southeast by Ho ...
is located at the base of Mount Wachusett, on the northwest side.


Flood-borne erratics

If glacial ice is "rafted" by a flood such as that created when the ice dam broke during the
Missoula Floods The Missoula floods (also known as the Spokane floods or the Bretz floods or Bretz's floods) were cataclysmic glacial lake outburst floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the las ...
, then the erratics are deposited where the ice finally releases its debris load. One of the more unusual examples is found far from its origin in Idaho at Erratic Rock State Natural Site just outside
McMinnville, Oregon McMinnville is the county seat of and largest city in Yamhill County, Oregon, United States. The city is named after McMinnville, Tennessee. As of the 2019 census, the city had a population estimate of 34,743. McMinnville is at the confluence of ...
. The park includes a specimen, the largest erratic found in the
Willamette Valley The Willamette Valley ( ) is a long valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the east ...
.


See also

* Glacial erratic boulders of the Puget Sound region * Grannie stone * Jasper conglomerate * Precarious boulder * Sunday Rock *
Willamette Meteorite The Willamette Meteorite, officially named WillametteMeteoritical Bulleti ...


References

* Imbrie, J. & K. P. Imbrie. ''Ice Ages'', Enslow Publishers, Hillside, New Jersey, 1979.


External links


Royal Alberta Museum
{{DEFAULTSORT:Glacial Erratic