Glacial erratic boulders of Estonia

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The Letipea boulder (Ehalkivi) in 2009 Letipea hiidrahn.jpg
The Letipea boulder (Ehalkivi) in 2009

Glacial erratic boulders of Estonia are large boulders of rock which have been formed and moved into Estonia by glacial action during previous ice ages. [1] They are now registered and protected by the government. [2]

Glacial erratic boulders are found in especially large quantities in Estonia. Most of the boulders greater than 30 metres in circumference found in northern Europe are in Estonia, which has 62 known boulders of this size. Some particular large ones have been found in the sea, including some near Osmussaar that are 100 metres diameter. The Osmussaar boulders are believed to have been pushed there by glaciers from the Neugrund meteorite crater. [3]

The Estonian boulders were important in the development of the idea that northern Europe was once covered in glaciers. The first to suggest that the boulders were moved by glaciers was Russian mineralogist Vasily Severgin who was led to this conclusion by their similarity to Finnish basement rock at the very early date of 1815. Severgin was later to retract this theory in favour of the drift theory of Charles Lyell who believed they had been carried by icebergs. However, later in the 19th century the glaciation theory slowly gained the ascendancy. [3]

List of boulders

Ehalkivi (Sunset Glow Boulder) near Letipea is the largest erratic boulder in the glaciation area of North Europe. It has a height of 7 m, circumference of 48.2 m, a volume of 930 m3 and a mass of approximately 2,500 tonnes.

59°32′59″N26°35′15″E / 59.5498°N 26.5876°E / 59.5498; 26.5876

Ehalkivi 2.jpg
The Kabelikivi is the second largest erratic boulder in Estonia, situated in Muuga, Viimsi Parish. It is 18.7 m long, 14.9 m wide and 6.4 m high, above ground volume is 728 m³. Muuga Kabelikivi 07Oct2015.JPG
The Aruküla Rock (Estonian: Aruküla hiidrahn) is a glacial erratic on the field of Aruküla, situated in Harju County, Estonia. It has a circumference of 35.2 m, height of 6.2 m.

59°12′50″N25°24′18″E / 59.2140°N 25.4049°E / 59.2140; 25.4049

Arukula boulder.JPG
Assaku Nõiakivi. Located in Assaku
Helgikivi. Situated in Kähu, Tõrva Parish, Valga County.
Helmersen Rock Field. Located in Hiiu Parish
Tubala boulder

58°57′37″N22°46′18″E / 58.9602°N 22.7718°E / 58.9602; 22.7718

Tubala boulder 1.jpg
Rock of Uku. Located in Harju County, Saue Parish, Muusika village
Vaindloo Boulder. Located in Vaindloo

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<span class="mw-page-title-main">Ice age</span> Period of long-term reduction in temperature of Earths surface and atmosphere

An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the ice age called Quaternary glaciation. Individual pulses of cold climate within an ice age are termed glacial periods, and intermittent warm periods within an ice age are called interglacials or interstadials.

<span class="mw-page-title-main">Pleistocene</span> First epoch of the Quaternary Period

The Pleistocene is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek πλεῖστος (pleîstos), meaning "most", and καινός, meaning "new".

<span class="mw-page-title-main">Wisconsin glaciation</span> North American glacial ice sheet

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<span class="mw-page-title-main">Last Glacial Period</span> Period of major glaciations of the northern hemisphere (115,000–12,000 years ago)

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<span class="mw-page-title-main">Glacial erratic</span> Piece of rock that has been moved by a glacier

A glacial erratic is a glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word errare, are carried by glacial ice, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large boulders such as Big Rock in Alberta.

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<span class="mw-page-title-main">Glacial landform</span> Landform created by the action of glaciers

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<span class="mw-page-title-main">Okotoks Erratic</span> Glacial erratic in Alberta, Canada

Okotoks Erratic is a 16,500-tonne (18,200-ton) boulder that lies on the otherwise flat, relatively featureless, surface of the Canadian Prairies in Alberta. It is part of the 930-kilometre-long (580 mi) Foothills Erratics Train of typically angular boulders of distinctive quartzite and pebbly quartzite.

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In glaciology, a roche moutonnée is a rock formation created by the passing of a glacier. The passage of glacial ice over underlying bedrock often results in asymmetric erosional forms as a result of abrasion on the "stoss" (upstream) side of the rock and plucking on the "lee" (downstream) side. Some geologists limit the term to features on scales of a metre to several hundred metres and refer to larger features as crag and tail.

<span class="mw-page-title-main">Plucking (glaciation)</span> Glacial erosion of bedrock

Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the weathering and erosion of pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier". As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock. The freezing and thawing action of the ice enlarges, widens, or causes further cracks in the bedrock as it changes volume across the ice/water phase transition, gradually loosening the rock between the joints. This produces large pieces of rock called joint blocks. Eventually these joint blocks come loose and become trapped in the glacier.

<span class="mw-page-title-main">Quaternary glaciation</span> Series of alternating glacial and interglacial periods

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<span class="mw-page-title-main">Withrow Moraine and Jameson Lake Drumlin Field</span>

The Withrow Moraine and Jameson Lake Drumlin Field is a National Park Service–designated privately owned National Natural Landmark located in Douglas County, Washington state, United States. Withrow Moraine is the only Ice Age terminal moraine on the Waterville Plateau section of the Columbia Plateau. The drumlin field includes excellent examples of glacially-formed elongated hills.

<span class="mw-page-title-main">Foothills Erratics Train</span>

The Foothills Erratics Train is a 580 miles (930 km) long, narrow, linear scatter of thousands of typically angular boulders of distinctive quartzite and pebbly quartzite that lie on the surface of a generally north-south strip of the Canadian Prairies. These boulders, which are between 1 foot (0.30 m) and 135 feet (41 m) in length, are glacial erratics that lie upon a surficial blanket of Late Wisconsin glacial till. The largest glacial erratic within the Foothills Erratics Train is Big Rock.

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Boulder Park National Natural Landmark, of Douglas County, Washington, along with the nearby McNeil Canyon Haystack Rocks and Sims Corner Eskers and Kames natural landmarks, illustrate well-preserved examples of classic Pleistocene ice stagnation landforms that are found in Washington. These landforms include numerous glacial erratics and haystack rocks that occur near and on the Withrow Moraine, which is the terminal moraine of the Okanogan ice lobe.

<span class="mw-page-title-main">Balancing rock</span> Naturally occurring precariously balanced rock

A balancing rock, also called a balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock, or on glacial till. Some formations known by this name only appear to be balancing, but are in fact firmly connected to a base rock by a pedestal or stem.

<span class="mw-page-title-main">Geology of New England</span> Overview of the geology of New England

New England is a region in the North Eastern United States consisting of the states Rhode Island, Connecticut, Massachusetts, New Hampshire, Vermont, and Maine. Most of New England consists geologically of volcanic island arcs that accreted onto the eastern edge of the Laurentian Craton in prehistoric times. Much of the bedrock found in New England is heavily metamorphosed due to the numerous mountain building events that occurred in the region. These events culminated in the formation of Pangaea; the coastline as it exists today was created by rifting during the Jurassic and Cretaceous periods. The most recent rock layers are glacial conglomerates.

<span class="mw-page-title-main">Glacial erratics on and around Rügen</span>

This is a list of erratics on and around Rügen – the largest island off the Baltic coast of Germany. An erratic is usually defined as an individual block of rock lying on the surface of the land which has a volume of at least one cubic metre and which was transported by a glacier to its present site during the ice age.

<span class="mw-page-title-main">Edaga Arbi Glacials</span> Palaeozoic geological formation in Africa

The Edaga Arbi Glacials are a Palaeozoic geological formation in Tigray and in Eritrea. The matrix is composed of grey, black and purple clays, that contains rock fragments up to 6 metres across. Pollen dating yields a Late Carboniferous to Early Permian age.

References

  1. Katrina Z. S. Schwartz, Nature and National Identity After Communism, University of Pittsburgh Press, p. 224, ISBN   9780822973140
  2. Rob Smurr (2002), Nationalizing Nature: the history, preservation and meaning of glacial erratic boulders in Estonia
  3. 1 2 Anto Raukas, "Evolution of the theory of continental glaciation in northern and eastern Europe" in R. H. Grapes, D. R. Oldroyd, A. Grigelis (eds), History of Geomorphology and Quaternary Geology, pp. 79-86, Geological Society of London, 2008 ISBN   1862392552.