Tatshenshini-Alsek Provincial Park
Tatshenshini-Alsek Park or Tatshenshini-Alsek Provincial Wilderness Park is a provincial park in British Columbia, Canada 9,580 km2. It was established in 1993 after an intensive campaign by Canadian and American conservation organizations to halt mining exploration and development in the area, protect the area for its strong natural heritage and biodiversity values; the park is situated in the northwestern corner of British Columbia, bordering the American state of Alaska and the Canadian Yukon Territory. It nestles between Reserve in the Yukon and Glacier Bay & Wrangell-St. Elias National Parks and Preserves in Alaska, it is part of the Kluane-Wrangell-St. Elias-Glacier Bay-Tatshenshini-Alsek park system, in 1994 was designated as a UNESCO World Heritage Site. Over the centuries, numerous indigenous peoples lived in this area, including the historic Tlingit and Southern Tutchone, who built fishing villages along the rivers; the eastern edge of the park follows an ancient trade route used by the Chilkat to barter with the Tutchone.
In the mid-19th century, the sudden breakup of a natural dam on the Alsek River caused a severe flood. The dam had been formed by the advance of a glacier across the entire Alsek River channel. A wall of water 7 m high and 15 m wide swept an entire Tutchone village into the sea at Dry Bay, killing all the inhabitants. Tatshenshini-Alsek was one of the last areas of British Columbia to be explored. In the 1960s the first geological exploration for minerals took place in the area. Significant copper deposits were found in the vicinity of Windy Craggy Mountain, in the middle of the Tatshenshini region. In the mid-1970s two companies began rafting the Alsek rivers for the first time. In the mid-1980s a proposal surfaced to develop Windy Craggy peak into a huge open-pit mine. In 1991 Tatshenshini International was established, linking together the top 50 conservation organisations in North America. An intensive campaign followed in Canada and in the United States the U. S. Congress and the White House, when the active involvement of Vice-President Al Gore was enlisted.
BC Premier Mike Harcourt responded by undertaking a review of the issues surrounding Tatshenshini-Alsek by the Commission on Resources and the Environment. BC government under Premier Harcourt decided in June 1993 to protect Tatshenshini-Alsek as a Class A park; the owners of the Windy-Craggy mineral claims were given a $103.8 million settlement. In combination with the adjoining national parks, this completed protection of the world's largest international park complex; the International Union for the Conservation of Nature proposed the area for protection as a UNESCO World Heritage Site. The Kluane-Wrangell-St. Elias-Glacier Bay-Tatshenshini-Alsek transfrontalier park system comprising Kluane, Wrangell-St Elias, Glacier Bay and Tatshenshini-Alsek parks, was declared a UNESCO World Heritage Site in 1994 for the spectacular glacier and icefield landscapes, in addition to the importance of its habitat for grizzly bears and Dall sheep. In 1999, a party of sheep hunters found artifacts and remains of a young male at the foot of a glacier in the park.
The well-preserved frozen body turned out to be between 550 years old. Representatives of Champagne and Aishihik First Nations were consulted for this find on their historic territory, they named the young man. In addition, they agreed to scientific and DNA testing of the remains. Researchers recruited volunteers to see if people could be found who were genetically related to the "iceman"; some 241 volunteers were tested from the area Champagne and Aishihik First Nations, related peoples in Yukon, British Columbia and Alaska. Seventeen living relatives, including two sisters, were found in the Champagne and Aishihik First Nations who are related through a mitochondrial DNA match of the direct female line. Fifteen of these 17 identify as Wolf clan, suggesting the young man belonged to that clan. In the matrilineal kinship system, children are considered born into their mother's clan, descent is figured through the mother's line; the Alsek and Tatshenshini rivers flow through the park in glacier-carved U-shaped valleys.
These valleys through the coastal mountains allow moist ocean air into the cold interior. The quick change from ocean to interior environment, frequent floods and avalanches, a varied geology and great elevation changes have together created an exceptionally diverse range of habitat conditions. Tatshenshini-Alsek Park supports a large grizzly bear population. A green area that cuts through a barrier of mountain and ice connects coastal and interior grizzly bear populations and provides a perfect habitat; the park is the only Canadian home of the glacier bear. This rare blue-grey colour phase of the black bear is found only within the park and just over the border into the United States; as well as bears, Tatshenshini-Alsek Park supports Dall's sheep, exceptional numbers of mountain goats, Kenai moose, grey wolves, eagles and trumpeter swans. Along the coastline, sea lions and humpback whales can be seen. Alsek Ranges are situated there and Mount Fairweather, at 4,671 metres is the province’s highest peak.
The Tatshenshini-Alsek area lies in a region of high earthquake activity. Slippages along the Fairweather and Hubbard/Border Faults to the west and the Denali Fault to the north cause regular quakes. Alaska Boundary Dispute BCParks Global
Alaska is a U. S. state in the northwest extremity of North America, just across the Bering Strait from Asia. The Canadian province of British Columbia and territory of Yukon border the state to the east and southeast, its most extreme western part is Attu Island, it has a maritime border with Russia to the west across the Bering Strait. To the north are the Chukchi and Beaufort seas—southern parts of the Arctic Ocean; the Pacific Ocean lies to southwest. It is the largest U. S. state by the seventh largest subnational division in the world. In addition, it is the most sparsely populated of the 50 United States. Half of Alaska's residents live within the Anchorage metropolitan area. Alaska's economy is dominated by the fishing, natural gas, oil industries, resources which it has in abundance. Military bases and tourism are a significant part of the economy; the United States purchased Alaska from the Russian Empire on March 30, 1867, for 7.2 million U. S. dollars at two cents per acre. The area went through several administrative changes before becoming organized as a territory on May 11, 1912.
It was admitted as the 49th state of the U. S. on January 3, 1959. The name "Alaska" was introduced in the Russian colonial period when it was used to refer to the Alaska Peninsula, it was derived from an Aleut-language idiom. It means object to which the action of the sea is directed. Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America. It is technically part of the continental U. S. but is sometimes not included in colloquial use. S. called "the Lower 48". The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system; the state is bordered by Yukon and British Columbia in Canada, to the east, the Gulf of Alaska and the Pacific Ocean to the south and southwest, the Bering Sea, Bering Strait, Chukchi Sea to the west and the Arctic Ocean to the north.
Alaska's territorial waters touch Russia's territorial waters in the Bering Strait, as the Russian Big Diomede Island and Alaskan Little Diomede Island are only 3 miles apart. Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, the next largest state. Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the combined area of the next three largest states: Texas and Montana, it is larger than the combined area of the 22 smallest U. S. states. There are no defined borders demarcating the various regions of Alaska, but there are six accepted regions: The most populous region of Alaska, containing Anchorage, the Matanuska-Susitna Valley and the Kenai Peninsula. Rural unpopulated areas south of the Alaska Range and west of the Wrangell Mountains fall within the definition of South Central, as do the Prince William Sound area and the communities of Cordova and Valdez.
Referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States. As such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase; the region is dominated by the Alexander Archipelago as well as the Tongass National Forest, the largest national forest in the United States. It contains the state capital Juneau, the former capital Sitka, Ketchikan, at one time Alaska's largest city; the Alaska Marine Highway provides a vital surface transportation link throughout the area, as only three communities enjoy direct connections to the contiguous North American road system. Designated in 1963; the Interior is the largest region of Alaska. Fairbanks is the only large city in the region. Denali National Park and Preserve is located here. Denali is the highest mountain in North America. Southwest Alaska is a sparsely inhabited region stretching some 500 miles inland from the Bering Sea. Most of the population lives along the coast.
Kodiak Island is located in Southwest. The massive Yukon–Kuskokwim Delta, one of the largest river deltas in the world, is here. Portions of the Alaska Peninsula are considered part of Southwest, with the remaining portions included with the Aleutian Islands; the North Slope is tundra peppered with small villages. The area is known for its massive reserves of crude oil, contains both the National Petroleum Reserve–Alaska and the Prudhoe Bay Oil Field; the city of Utqiagvik known as Barrow, is the northernmost city in the United States and is located here. The Northwest Arctic area, anchored by Kotzebue and containing the Kobuk River valley, is regarded as being part of this region. However, the respective Inupiat of the No
Hoonah–Angoon Census Area, Alaska
Hoonah–Angoon Census Area is a census area located in the U. S. state of Alaska. As of the 2010 census, the population was 2,150, it therefore has no borough seat. Its largest community is the city of Hoonah; the census area was larger in the 1990 census, at which time it was the Skagway–Yakutat–Angoon Census Area. After Yakutat was incorporated as a consolidated-city borough on September 22, 1992, it was renamed Skagway–Hoonah–Angoon Census Area. According to the U. S. Census Bureau, the census area has a total area of 10,914 square miles, of which 7,525 square miles is land and 3,389 square miles is water. A map showing its current boundaries is shown here: Yakutat City and Borough, Alaska – northwest Haines Borough, Alaska – northeast Juneau City and Borough, Alaska – northeast Petersburg Borough, Alaska – southeast Sitka City and Borough, Alaska – southwest Stikine Region, British Columbia – northwest, east Kitimat-Stikine Regional District, British Columbia – southeast Glacier Bay National Park Glacier Bay Wilderness Tongass National Forest Admiralty Island National Monument Kootznoowoo Wilderness Chuck River Wilderness Pleasant/Lemesurier/Inian Islands Wilderness Tracy Arm-Fords Terror Wilderness West Chichagof-Yakobi Wilderness Note: Demographic data below is for the former "Skagway–Hoonah–Angoon" Census Area, which still includes Skagway Borough.
As of the census of 2000, there were 3,436 people, 1,369 households, 866 families residing in the census area. The population density was 0.30 people per square mile. There are 2,108 housing units; the racial makeup of the census area was 58.15% White, 0.15% Black or African American, 35.01% Native American, 0.38% Asian, 0.15% Pacific Islander, 0.96% from other races, 5.21% from two or more races. 2.82% of the population were Hispanic or Latino of any race. 3.95 % reported speaking Tlingit at home. There were 1,369 households out of which 30.80% had children under the age of 18 living with them, 49.30% were married couples living together, 8.40% had a female householder with no husband present, 36.70% were non-families. 30.10% of all households were made up of individuals and 5.60% had someone living alone, 65 years of age or older. The average household size was 2.50 and the average family size was 3.14. In the census area the population was spread out with 26.80% under the age of 18, 7.10% from 18 to 24, 29.50% from 25 to 44, 29.30% from 45 to 64, 7.30% who were 65 years of age or older.
The median age was 38 years. For every 100 females there were 116.40 males. For every 100 females age 18 and over, there were 120.70 males. Angoon Gustavus Hoonah Pelican Tenakee Springs Elfin Cove Game Creek Klukwan Whitestone Logging Camp Cube Cove List of airports in the Hoonah-Angoon Census Area Skagway-Hoonah-Angoon Census Area map, 2000 census: Alaska Department of Labor Hoonah-Angoon Census Area map, 2010 census: Alaska Department of Labor Hoonah-Angoon Census Area map, January 2014: Alaska Department of Labor Alaska ShoreZone Coastal Mapping and Imagery
A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form and alignment that have arisen from the same cause an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are found on many planetary mass objects in the Solar System and are a feature of most terrestrial planets. Mountain ranges are segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not have the same geologic structure or petrology, they may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, volcanic landforms resulting in a variety of rock types. Most geologically young mountain ranges on the Earth's land surface are associated with either the Pacific Ring of Fire or the Alpide Belt.
The Pacific Ring of Fire includes the Andes of South America, extends through the North American Cordillera along the Pacific Coast, the Aleutian Range, on through Kamchatka, Taiwan, the Philippines, Papua New Guinea, to New Zealand. The Andes is 7,000 kilometres long and is considered the world's longest mountain system; the Alpide belt includes Indonesia and Southeast Asia, through the Himalaya, Caucasus Mountains, Balkan Mountains fold mountain range, the Alps, ends in the Spanish mountains and the Atlas Mountains. The belt includes other European and Asian mountain ranges; the Himalayas contain the highest mountains in the world, including Mount Everest, 8,848 metres high and traverses the border between China and Nepal. Mountain ranges outside these two systems include the Arctic Cordillera, the Urals, the Appalachians, the Scandinavian Mountains, the Great Dividing Range, the Altai Mountains and the Hijaz Mountains. If the definition of a mountain range is stretched to include underwater mountains the Ocean Ridges form the longest continuous mountain system on Earth, with a length of 65,000 kilometres.
The mountain systems of the earth are characterized by a tree structure, where mountain ranges can contain sub-ranges. The sub-range relationship is expressed as a parent-child relationship. For example, the White Mountains of New Hampshire and the Blue Ridge Mountains are sub-ranges of the Appalachian Mountains. Equivalently, the Appalachians are the parent of the White Mountains and Blue Ridge Mountains, the White Mountains and the Blue Ridge Mountains are children of the Appalachians; the parent-child expression extends to the sub-ranges themselves: the Sandwich Range and the Presidential Range are children of the White Mountains, while the Presidential Range is parent to the Northern Presidential Range and Southern Presidential Range. The position of mountains influences climate, such as snow; when air masses move up and over mountains, the air cools producing orographic precipitation. As the air descends on the leeward side, it warms again and is drier, having been stripped of much of its moisture.
A rain shadow will affect the leeward side of a range. Mountain ranges are subjected to erosional forces which work to tear them down; the basins adjacent to an eroding mountain range are filled with sediments which are buried and turned into sedimentary rock. Erosion is at work while the mountains are being uplifted until the mountains are reduced to low hills and plains; the early Cenozoic uplift of the Rocky Mountains of Colorado provides an example. As the uplift was occurring some 10,000 feet of Mesozoic sedimentary strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to the east; this mass of rock was removed as the range was undergoing uplift. The removal of such a mass from the core of the range most caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment.
Computer simulation has shown that as mountain belts change from tectonically active to inactive, the rate of erosion drops because there are fewer abrasive particles in the water and fewer landslides. Mountains on other planets and natural satellites of the Solar System are isolated and formed by processes such as impacts, though there are examples of mountain ranges somewhat similar to those on Earth. Saturn's moon Titan and Pluto, in particular exhibit large mountain ranges in chains composed of ices rather than rock. Examples include the Mithrim Montes and Doom Mons on Titan, Tenzing Montes and Hillary Montes on Pluto; some terrestrial planets other than Earth exhibit rocky mountain ranges, such as Maxwell Montes on Venus taller than any on Earth and Tartarus Montes on Mars, Jupiter's moon Io has mountain ranges formed from tectonic processes including Boösaule Montes, Dorian Montes, Hi'iaka Montes and Euboea Montes. Peakbagger Ranges Home Page Bivouac.com
The City and Borough of Yakutat is a borough in the U. S. was the name of a former city within it. The name is Tlingit, Yaakwdáat but it derives from an Eyak name diyaʼqudaʼt and was influenced by the Tlingit word yaakw; the borough covers an area about six times the size of the U. S. state of Rhode Island, making it one of the largest counties in the United States. As of the 2010 census, the population was 662, down from 680 in 2000; the Borough of Yakutat was incorporated as a non-unified Home Rule Borough on September 22, 1992, Yakutat was a city in the Skagway–Yakutat–Angoon Census Area. The U. S. Census Bureau has defined the former City of Yakutat as a census-designated place within the borough; the only other significant population center in the borough is the community of Icy Bay, the site of the Icy Bay Airport, in the west-central part of the borough. The original settlers in the Yakutat area are believed to have been Eyak-speaking people from the Copper River area. Tlingits assimilated the Eyaks before the arrival of Europeans in Alaska.
Yakutat was only one of a number of Tlingit and mixed Tlingit-Eyak settlements in the region, although all the others have been depopulated or abandoned. In the eighteenth and nineteenth centuries, French and Russian explorers came to the region; the Shelikhov-Golikov Company, precursor of the Russian-American Company, built a fort in Yakutat in 1795 to facilitate trade in sea otter pelts. It was known as Yakutat Colony, or Slavorossiya; when the Russians cut off access to the fisheries nearby, a Tlingit war party attacked and destroyed the fort. By 1886, after the Alaska Purchase by the United States, the black sand beaches in the area were being mined for gold. In 1889 the Swedish Free Mission Church opened a sawmill in the area. A cannery, another sawmill, a store and a railroad were constructed from 1903 by the Stimson Lumber Company. Many people moved to the current site of Yakutat to be closer to the Stimson cannery, which operated through 1970. During World War II, the USAAF stationed a large aviation garrison near Yakutat and built a paved runway.
The troops were withdrawn after the war but the runway is still in use as Yakutat Airport, which offers scheduled airline service. Fishing is the largest economic activity in Yakutat. Yakutat Tlingit Tribe received a Language Preservation Grant from the Administration for Native Americans in 2004. With this, they have reinvigorated their efforts to teach the Tlingit language to middle-aged and young people. YTT is expanding its role in the schools. All the YTT Tlingit language revitalization work focuses on using communicative approaches to second language teaching, such as TPR and ASLA. While working at a local cannery from 1912 to 1941, Seiki Kayamori extensively photographed Yakutat and its area. A large set of prints of his work is held by Yakutat City Hall. Yakutat and Southern Railway was a rail operation in the area. According to the U. S. Census Bureau, the borough has a total area of 9,463 square miles, of which 7,649 square miles is land and 1,813 square miles is water; the 2010 census defines a smaller census-designated place named Yakutat which has a total area of 104.1 square miles, of which 100.5 square miles is land and 3.6 square miles is water.
Yakutat's population center is located at 59°32′49″N 139°43′38″W, at the mouth of Yakutat Bay. It lies in an isolated location in lowlands along the Gulf of Alaska, 212 miles ) northwest of Juneau. Yakutat borders the Gulf of Alaska to the west, Valdez-Cordova Census Area, Alaska to the northwest, Hoonah-Angoon Census Area, Alaska to the southeast, Stikine Region, British Columbia to the northeast-east and Yukon Territory to the north; the borough contains part of the protected areas of Chugach National Forest, Glacier Bay National Park, Glacier Bay Wilderness, Tongass National Forest, Wrangell-St. Elias National Park and Preserve, Wrangell-Saint Elias Wilderness and the Russell Fjord Wilderness. One unique feature in the Borough is North America's largest tide-water glacier. In 1986 and 2002, the glacier blocked the entrance to Russell Fiord; the resulting Russell Lake rose 61 feet, until the glacial dam failed. If Russell Lake rises to 135 feet, the water will spill over a flow into the Situk River.
This will have a major impact on a world-class fishery. Yakutat will not be impacted unless the glacier advances to the townsite, which could take a thousand years; the vegetation in the area indicates that water was flowing over the pass until about 1860. Yakutat has a subarctic climate but with characteristics such as high precipitation, absence of frozen soil and temperate rainforest vegetation of the subpolar oceanic climate zone of the Pacific Coast, it rivals Ketchikan as the wettest "city" in the United States, with an annual precipitation of 155 inches, which falls on 240 days of the year, including 150 inches of snow all of it falling from November through April, that occurs on 64 days annually. September and October represent, on average, the year's primary "rainy season," with an average of over 20 inches of preci
Saint Elias Mountains
The Saint Elias Mountains are a subgroup of the Pacific Coast Ranges, located in southeastern Alaska in the United States, Southwestern Yukon and the far northwestern part of British Columbia in Canada. The range spans Wrangell-St. Elias National Park and Preserve in the United States and Kluane National Park and Reserve in Canada and includes all of Glacier Bay National Park in Alaska. In Alaska, the range includes parts of the city/borough of Yakutat and the Hoonah-Angoon and Valdez-Cordova census areas; this mountain range was named after Mount Saint Elias, named in 1741 by the Danish explorer Vitus Bering. The St. Elias Mountains is the highest coastal mountain range on Earth, it formed due to the subduction of the Yakutat microplate underneath the North American Plate. The Yakutat microplate is a wedge shaped oceanic plateau with 20–30 km thickness. Similar to the adjacent Pacific plate the Yakutat plate is moving northwestward with a rate of ~50 mm/year with respect to North America; the Yakutat plate is transported northwards along the active Fairweather Fault, which started more than 35 million years ago.
Due to its thickness the Yakutat plate is buoyant resulting in surface uplift of the overriding North American plate, which formed the Talkeetna Mountains and the Alaska Range in southcentral Alaska located above the subducted part of the Yakutat plate. The St. Elias Mountains formed at the plate boundary between the North American plate; the up to 12 km thick sediments that have been deposited on top of the Yakutat plate are imbricated and deformed as they became scraped off and compose today the southern flanks of the St. Elias Mountains. In contrast the high elevated regions of the drainage divide and north of it are composed of rocks that are part of the North American plate; the highest peaks of the St. Elias Mountains are located in the high ice field region of the Kluane National Park and north of the Malaspina Glacier, in the region known as the St. Elias syntaxis. At the syntaxis region the tectonic style changes from strike-slip motion along the Fairweather Fault to collision west of Malaspina Strait.
This tectonic transition concentrates stress in the crust at the syntaxis that together with efficient glacial erosion results in positive feedback processes that through time forms extreme high mountain peaks and local relief, rapid exhumation of rocks from up to 10 km depths to the surface. The mountains are divided by the Duke Depression, with the shorter, more rounded Kluane Ranges to the east, the higher Icefield Ranges to the west. Sub-ranges of the Saint Elias include the Alsek Ranges, the Fairweather Range, the Centennial Range; the highest mountains of the range include: Richter, Donald H.. Geologic Map of the Wrangell-Saint Elias National Park and Preserve, Alaska. USGS Scientific Investigations Map 2877. Winkler, Gary R.. A Geologic Guide to Wrangell—Saint Elias National Park and Preserve, Alaska: A Tectonic Collage of Northbound Terranes. USGS Professional Paper 1616. ISBN 978-0-607-92676-7. Wood, Charles A.. Volcanoes of North America. Cambridge University Press. ISBN 978-0-521-43811-7
A geologic map or geological map is a special-purpose map made to show geological features. Rock units or geologic strata are shown by color or symbols to indicate where they are exposed at the surface. Bedding planes and structural features such as faults, folds and lineations are shown with strike and dip or trend and plunge symbols which give these features' three-dimensional orientations. Stratigraphic contour lines may be used to illustrate the surface of a selected stratum illustrating the subsurface topographic trends of the strata. Isopach maps detail the variations in thickness of stratigraphic units, it is not always possible to properly show this when the strata are fractured, mixed, in some discontinuities, or where they are otherwise disturbed. Rock units are represented by colors. Instead of colors, certain symbols can be used. Different geologic mapping agencies and authorities have different standards for the colors and symbols to be used for rocks of differing types and ages. Geologists take two major types of orientation measurements: orientations of planes and orientations of lines.
Orientations of planes are measured as a "strike" and "dip", while orientations of lines are measured as a "trend" and "plunge". Strike and dip symbols consist of a long "strike" line, perpendicular to the direction of greatest slope along the surface of the bed, a shorter "dip" line on side of the strike line where the bed is going downwards; the angle that the bed makes with the horizontal, along the dip direction, is written next to the dip line. In the azimuthal system and dip are given as "strike/dip". Trend and plunge are used for linear features, their symbol is a single arrow on the map; the arrow is oriented in the downgoing direction of the linear feature and at the end of the arrow, the number of degrees that the feature lies below the horizontal is noted. Trend and plunge are notated as PLUNGE → TREND; the oldest preserved geologic map is the Turin papyrus, which shows the location of building stone and gold deposits in Egypt. The earliest geologic map of the modern era is the 1771 "Map of Part of Auvergne, or figures of, The Current of Lava in which Prisms, Etc. are Made from Basalt.
To be used with Mr. Demarest's theories of this hard basalt. Engraved by Messr. Pasumot and Daily, Geological Engineers of the King." This map is based on Nicolas Desmarest's 1768 detailed study of the geology and eruptive history of the Auvergne volcanoes and a comparison with the columns of the Giant's Causeway of Ireland. He identified both landmarks as features of extinct volcanoes; the 1798 report was incorporated in the 1771 Royal Academy of Science compendium. The first geological map of the U. S. was produced in 1809 by William Maclure. In 1807, Maclure undertook the self-imposed task of making a geological survey of the United States, he mapped nearly every state in the Union. During the rigorous two-year period of his survey, he crossed and recrossed the Allegheny Mountains some 50 times. Maclure's map shows the distribution of five classes of rock in what are now only the eastern states of the present-day US; the first geologic map of Great Britain was created by William Smith in 1815 using principles first formulated by Smith.
In the United States, geologic maps are superimposed over a topographic map with the addition of a color mask with letter symbols to represent the kind of geologic unit. The color mask denotes the exposure of the immediate bedrock if obscured by soil or other cover; each area of color denotes a geologic unit or particular rock formation. However, in areas where the bedrock is overlain by a thick unconsolidated burden of till, terrace sediments, loess deposits, or other important feature, these are shown instead. Stratigraphic contour lines, fault lines and dip symbols, are represented with various symbols as indicated by the map key. Whereas topographic maps are produced by the United States Geological Survey in conjunction with the states, geologic maps are produced by the individual states. There are no geologic map resources for some states, while a few states, such as Kentucky and Georgia, are extensively mapped geologically. In the United Kingdom the term geological map is used; the UK and Isle of Man have been extensively mapped by the British Geological Survey since 1835.
Two 1:625,000 scale maps cover the basic geology for the UK. More detailed sheets are available at scales of 1:250,000, 1:50,000 and 1:10,000; the 1:625,000 and 1:250,000 scales show both onshore and offshore geology, whilst other scales cover exposures on land only. Sheets of all scales fall into two categories: Superficial deposit maps show both bedrock and the deposits on top of it. Bedrock maps show the underlying rock, without superficial deposits; the maps are superimposed over a topographic map base produced by Ordnance Survey, use symbols to represent fault lines and dip or geological units, boreholes etc. Colors are used to represent different geological units. Explanatory booklets (