The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, the longest period of the Phanerozoic Eon; the Cretaceous Period is abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas; these oceans and seas were populated with now-extinct marine reptiles and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; the Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use; as with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
Banner Peak is the second tallest peak in the Ritter Range of California's Sierra Nevada. The mountain is 12,942 feet tall, there are several glaciers on its slopes, it lies within the boundaries of the Ansel Adams Wilderness. Banner Peak is near the town of Mammoth Lakes. Other nearby lakes include Shadow Lake; the peak was named in 1883 by USGS topographer Willard D. Johnson who observed a banner cloud streaming from the summit
Berlin is the capital and largest city of Germany by both area and population. Its 3,748,148 inhabitants make it the second most populous city proper of the European Union after London; the city is one of Germany's 16 federal states. It is surrounded by the state of Brandenburg, contiguous with its capital, Potsdam; the two cities are at the center of the Berlin-Brandenburg capital region, which is, with about six million inhabitants and an area of more than 30,000 km², Germany's third-largest metropolitan region after the Rhine-Ruhr and Rhine-Main regions. Berlin straddles the banks of the River Spree, which flows into the River Havel in the western borough of Spandau. Among the city's main topographical features are the many lakes in the western and southeastern boroughs formed by the Spree and Dahme rivers. Due to its location in the European Plain, Berlin is influenced by a temperate seasonal climate. About one-third of the city's area is composed of forests, gardens, rivers and lakes; the city lies in the Central German dialect area, the Berlin dialect being a variant of the Lusatian-New Marchian dialects.
First documented in the 13th century and situated at the crossing of two important historic trade routes, Berlin became the capital of the Margraviate of Brandenburg, the Kingdom of Prussia, the German Empire, the Weimar Republic, the Third Reich. Berlin in the 1920s was the third largest municipality in the world. After World War II and its subsequent occupation by the victorious countries, the city was divided. East Berlin was declared capital of East Germany. Following German reunification in 1990, Berlin once again became the capital of all of Germany. Berlin is a world city of culture, politics and science, its economy is based on high-tech firms and the service sector, encompassing a diverse range of creative industries, research facilities, media corporations and convention venues. Berlin serves as a continental hub for air and rail traffic and has a complex public transportation network; the metropolis is a popular tourist destination. Significant industries include IT, biomedical engineering, clean tech, biotechnology and electronics.
Berlin is home to world-renowned universities, orchestras and entertainment venues, is host to many sporting events. Its Zoological Garden is one of the most popular worldwide. With the world's oldest large-scale movie studio complex, Berlin is an popular location for international film productions; the city is well known for its festivals, diverse architecture, contemporary arts and a high quality of living. Since the 2000s Berlin has seen the emergence of a cosmopolitan entrepreneurial scene. Berlin lies in northeastern Germany, east of the River Saale, that once constituted, together with the River Elbe, the eastern border of the Frankish Realm. While the Frankish Realm was inhabited by Germanic tribes like the Franks and the Saxons, the regions east of the border rivers were inhabited by Slavic tribes; this is why most of the villages in northeastern Germany bear Slavic-derived names. Typical Germanised place name suffixes of Slavic origin are -ow, -itz, -vitz, -witz, -itzsch and -in, prefixes are Windisch and Wendisch.
The name Berlin has its roots in the language of West Slavic inhabitants of the area of today's Berlin, may be related to the Old Polabian stem berl-/birl-. Since the Ber- at the beginning sounds like the German word Bär, a bear appears in the coat of arms of the city, it is therefore a canting arm. Of Berlin's twelve boroughs, five bear a Slavic-derived name: Pankow, Steglitz-Zehlendorf, Marzahn-Hellersdorf, Treptow-Köpenick and Spandau. Of its ninety-six neighborhoods, twenty-two bear a Slavic-derived name: Altglienicke, Alt-Treptow, Buch, Gatow, Kladow, Köpenick, Lankwitz, Lübars, Marzahn, Prenzlauer Berg, Schmöckwitz, Stadtrandsiedlung Malchow, Steglitz and Zehlendorf; the neighborhood of Moabit bears a French-derived name, Französisch Buchholz is named after the Huguenots. The earliest evidence of settlements in the area of today's Berlin are a wooden beam dated from 1192, remnants of a house foundation dated to 1174, found in excavations in Berlin Mitte; the first written records of towns in the area of present-day Berlin date from the late 12th century.
Spandau is first mentioned in 1197 and Köpenick in 1209, although these areas did not join Berlin until 1920. The central part of Berlin can be traced back to two towns. Cölln on the Fischerinsel is first mentioned in a 1237 document, Berlin, across the Spree in what is now called the Nikolaiviertel, is referenced in a document from 1244. 1237 is considered the founding date of the city. The two towns over time formed close economic and social ties, profited from the staple right on the two important trade routes Via Imperii and from Bruges to Novgorod. In 1307, they formed an alliance with a common external policy, their internal administrations still being separated. In 1415, Frederick I became the elector of the Margraviate of Brandenburg, which he ruled until 1440. During the 15th century, his successors established Berlin-Cölln as capital of the margraviate, subsequent members of the Hohenzol
California Geological Survey
The California Geological Survey known as the California Division of Mines and Geology, is the California state geologic agency. Although it was not until 1880 that the California State Mining Bureau, predecessor to the California Geological Survey, was established, the "roots" of California's state geological survey date to an earlier time; as might be expected for a state that owed its existence to the gold rush of 1849, the California State Legislature recognized that geologists could provide valuable information. In 1851, one year after California was admitted to the United States, the Legislature named John B. Trask, a medical practitioner and active member of the California Academy of Sciences, as Honorary State Geologist. In 1853 the Legislature passed a joint resolution asking him for geological information about the state, he submitted a report On California Range. About two months the Legislature created the first California Geological Survey headed by Trask, who retained the title of State Geologist.
Within a few years the mining of placer gold began to decline and mining of quartz lodes began. These changes, coupled with publication of reports by Trask, created a public clamor for a state geological survey. In 1860 the Legislature passed an act creating the Office of State Geologist and defining the duties thereof; the act named Josiah D. Whitney to fill the office. A Yale graduate, Whitney had worked on several surveys in the east; the act directed Whitney to make an complete geological survey of the state. Whitney chose William Henry Brewer as chief botanist to lead the original field party. Brewer added Clarence King, James Gardiner, topographer Charles F. Hoffmann and packer Dick Cotter, it was one of the most ambitious geological surveys attempted and yielded a vast amount of information about California, hitherto unknown and unpublished. Among the natural features of California they were the first to describe Kings Canyon, which they discovered in 1864; the original California Geological Survey influenced the future of surveying and spurred the creation of the United States Geological Survey.
Funding for the field work was limited and the last field work was done in 1870 by Hoffmann and W. A. Goodyear. In 1874 the Survey was ended due to hostility between Governor of California Newton Booth and Whitney. In 1880 the State Mining Bureau was established by the Legislature; the establishment of the Bureau was a direct action in response to the need for information on the occurrence and processing of gold in the state. Its focus was on the Governor appointed the State Mineralogist. In 1891, the Bureau published the first geologic map of the state showing eight stratigraphic units in color, along with numerous blank areas where information was lacking; the second colored geologic map of the state, published in 1916, showed 21 stratigraphic units and was accompanied by an explanatory volume. In 1927 the Bureau became the Division of Mines within the Department of Natural Resources. In 1928, with the hiring of the first geologist, the focus of the Division began to shift towards the gathering of basic geologic information.
In 1938 a new 1:500,000-scale geologic map was published. During the 1940s and 1950s, the Division developed as a state geological survey and two well-defined branches were established: the Mining Engineering Branch and the Geology Branch; the Division began processing numerous geological quadrangle reports for publication. In 1952 the Division conducted its first public-safety related effort by documenting the impacts of the 1952 Kern County earthquake and its aftershocks; the 1960s were years of modernization of long-standing programs. In 1962, eighty-one years after its creation, the Division of Mines was renamed the Division of Mines and Geology, its focus had shifted from an organization, mine-oriented to one responsible for a broader range of practical applications of geology geologic hazards and seismic hazards. A highlight of the decade was the completion in 1966 of the geologic mapping program. From the early 1970s to the present, Division programs have expanded due to the passage of legislation.
Following earthquakes and landslide damage during the 1970s and 1980s, legislation passed which focused DMG’s authority on several fronts, including: Establishing the Strong-Motion Instrumentation Program to obtain statewide records of the response of rock and structures to ground motion caused by earthquakes. Enacting the Alquist Priolo Special Studies Zone Act, mandating the delineation of zones along traces of hazardous faults. Enacting the Surface Mining and Reclamation Act to ensure that significant mineral deposits are identified and protected and the reclamation of mined lands. Declaring that the California Department of Conservation is the primary state agency responsible for geologic hazard review and investigation. Enacting the Seismic Hazards Mapping Act, establishing a program to identify and map seismic hazard zones. Language was added which outlined DMG’s responsibilities as encompassing: Hazard assessment – identification and mapping of geologic hazards and estimates of potential consequences and likelihood of occurrence.
Information and advisory services including maintenance of a geologic library, public education program, maintenance of a geologic data base, review functions, expert consulting to federal and local government agencies. Emergency response including monitoring and assessment of anomalous geologic activity, operation of a clearinghouse for post-event earth science investigations. Developm
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