Aquascaping is the craft of arranging aquatic plants, as well as rocks, cavework, or driftwood, in an aesthetically pleasing manner within an aquarium—in effect, gardening under water. Aquascape designs include a number of distinct styles, including the garden-like Dutch style and the Japanese-inspired nature style. An aquascape houses fish as well as plants, although it is possible to create an aquascape with plants only, or with rockwork or other hardscape and no plants. Although the primary aim of aquascaping is to create an artful underwater landscape, the technical aspects of tank maintenance and the growth requirements of aquatic plants are taken into consideration. Many factors must be balanced in the closed system of an aquarium tank to ensure the success of an aquascape; these factors include filtration, maintaining carbon dioxide at levels sufficient to support photosynthesis underwater and fertilization, algae control. Aquascape hobbyists trade plants, conduct contests, share photographs and information via the Internet.
The United States-based Aquatic Gardeners Association has about 1,200 members. The Dutch aquarium employs a lush arrangement in which multiple types of plants having diverse leaf colors and textures are displayed much as terrestrial plants are shown in a flower garden; this style was developed in the Netherlands starting in the 1930s, as freshwater aquarium equipment became commercially available. It emphasizes plants located on terraces of different heights, omits rocks and driftwood. Linear rows of plants running left-to-right are referred to as "Dutch streets". Although many plant types are used, one sees neatly trimmed groupings of plants with fine, feathery foliage, such as Limnophila aquatica and various types of Hygrophila, along with the use of red-leaved Alternanthera reineckii, Ammania gracilis, assorted Rotala for color highlights. More than 80% of the aquarium floor is covered with plants, little or no substrate is left visible. Tall growing plants that cover the back glass served the purpose of hiding bulky equipment behind the tank.
A contrasting approach is the "nature aquarium" or Japanese style, introduced in the 1990s by Takashi Amano. Amano's three-volume series, Nature Aquarium World, sparked a wave of interest in aquarium gardening, he has been cited as having "set a new standard in aquarium management". Amano's compositions drew on Japanese gardening techniques that attempt to mimic natural landscapes by the asymmetrical arrangement of masses of few species of plants, which set rules governing selected stones or driftwood with a single focal point; the objective is to evoke a terrestrial landscape in miniature, rather than a colorful garden. This style draws from the Japanese aesthetic concepts of Wabi-sabi, which focuses on transience and minimalism as sources of beauty. Plants with small leaves like Glossostigma elatinoides, Eleocharis acicularis, Eleocharis parvula, Echinodorus tenellus, Hemianthus callitrichoides, Riccia fluitans, small aquatic ferns, Staurogyne repens, Java moss are used to emulate grass or moss.
Colors are more limited than in the Dutch style, the hardscape is not covered. Fish, or freshwater shrimp such as Caridina multidentata and Neocaridina heteropoda, are selected to complement the plants and control algae, but for reasons of minimalism the number of species are limited; the Iwagumi style is a specific subtype of the nature style. The Iwagumi term itself comes from the Japanese "rock formation" and refers to a layout where stones play a leading role. In the Iwagumi style, each stone has a specific role. Rocks provide the bony structure of the aquascape and the typical geometry employs a design with three main stones, with one larger stone and two other smaller stones, although additional rocks can be used; the Oyaishi, or main stone, is placed off-center in the tank, Soeishi, or accompanying stones, are grouped near it, while Fukuseki, or secondary stones, are arranged in subordinate positions. The location of the focal point of the display, determined by the asymmetric placement of the Oyaishi, is considered important, follows ratios that reflect Pythagorean tuning.
Some hobbyists refer to a "jungle" style, separate from either the Dutch or nature styles, incorporating some of the features of them both. The plants are left to assume a untrimmed look. Jungle style aquascapes have little or no visible hardscape material, as well as limited open space. Bold, coarser leaf shapes, such as Echinodorus bleheri, are used to provide a wild, untamed appearance. Unlike nature syle, the jungle style does not employ fine textures. A jungle canopy effect can be obtained using combinations of darker substrates, tall plants growing up to the surface, floating plants that block light, offering a dappled lighting effect. Other plants used in jungle style aquascapes include Microsorum pteropus, Bolbitis heudelotii, Vallisneria americana, Crinum species, Aponogeton species, Echinodorus species, Sagittaria subulata, Hygrophila pinnatifida, Anubias species, Limnobium laevigatum; the styles above combine plant and animal species based on the desired visual impact, without regard to geographic origin.
Biotope aquariums are designed instead to replicate a particular aquatic habitat at a particular geographic location, not to provide a gardenlike display. Plants and fish need not be present at all, but if they are, they must match what would be found in nature in the habitat being represented, as must any gravel and hardscape, an
Sequoia sempervirens is the sole living species of the genus Sequoia in the cypress family Cupressaceae. Common names include coastal redwood and California redwood, it is an evergreen, long-lived, monoecious tree living 1,200 -- more. This species includes the tallest living trees on Earth, reaching up to 379 feet in height and up to 29.2 feet in diameter at breast height. These trees are among the oldest living things on Earth. Before commercial logging and clearing began by the 1850s, this massive tree occurred in an estimated 2,100,000 acres along much of coastal California and the southwestern corner of coastal Oregon within the United States; the name sequoia sometimes refers to the subfamily Sequoioideae, which includes S. sempervirens along with Sequoiadendron and Metasequoia. Here, the term redwood on its own refers to the species covered in this article, not to the other two species. Scottish botanist David Don described the redwood as the evergreen taxodium in his colleague Aylmer Bourke Lambert's 1824 work A description of the genus Pinus.
Austrian botanist Stephan Endlicher erected the genus Sequoia in his 1847 work Synopsis coniferarum, giving the redwood its current binomial name of Sequoia sempervirens. Endlicher derived the name Sequoia from the Cherokee name of George Gist spelled Sequoyah, who developed the still-used Cherokee syllabary; the redwood is one of each in its own genus, in the subfamily Sequoioideae. Molecular studies have shown that the three are each other's closest relatives with the redwood and giant sequoia as each other's closest relatives; however and colleagues in 2010 queried the polyploid state of the redwood and speculate that it may have arisen as an ancient hybrid between ancestors of the giant sequoia and dawn redwood. Using two different single copy nuclear genes, LFY and NLY, to generate phylogenetic trees, they found that Sequoia was clustered with Metasequoia in the tree generated using the LFY gene, but with Sequoiadendron in the tree generated with the NLY gene. Further analysis supported the hypothesis that Sequoia was the result of a hybridization event involving Metasequoia and Sequoiadendron.
Thus and colleagues hypothesize that the inconsistent relationships among Metasequoia and Sequoiadendron could be a sign of reticulate evolution among the three genera. However, the long evolutionary history of the three genera make resolving the specifics of when and how Sequoia originated once and for all a difficult matter—especially since it in part depends on an incomplete fossil record; the coast redwood can reach 115 m tall with a trunk diameter of 9 m. It has a conical crown, with horizontal to drooping branches; the bark can be thick, up to 1-foot, quite soft and fibrous, with a bright red-brown color when freshly exposed, weathering darker. The root system is composed of wide-spreading lateral roots; the leaves are variable, being 15–25 mm long and flat on young trees and shaded shoots in the lower crown of old trees. On the other hand, they are scale-like, 5–10 mm long on shoots in full sun in the upper crown of older trees, with a full range of transition between the two extremes.
They have two blue-white stomatal bands below. Leaf arrangement is spiral, but the larger shade leaves are twisted at the base to lie in a flat plane for maximum light capture; the species is monoecious, with seed cones on the same plant. The seed cones are ovoid, 15–32 mm long, with 15–25 spirally arranged scales; each cone scale bears three to seven seeds, each seed 3–4 mm long and 0.5 mm broad, with two wings 1 mm wide. The seeds are open at maturity; the pollen cones are 4 -- 6 mm long. Its genetic makeup is unusual among conifers, being a hexaploid and allopolyploid. Both the mitochondrial and chloroplast genomes of the redwood are paternally inherited. Coast redwoods occupy a narrow strip of land 750 km in length and 5–47 mi in width along the Pacific coast of North America; the prevailing elevation range is 98–2,460 ft above sea level down to 0 and up to 3,000 ft. They grow in the mountains where precipitation from the incoming moisture off the ocean is greater; the tallest and oldest trees are found in deep valleys and gullies, where year-round streams can flow, fog drip is regular.
The trees above the fog layer, above about 2,296 ft, are shorter and smaller due to the drier and colder conditions. In addition, Douglas fir and tanoak crowd out redwoods at these elevations. Few redwoods grow close to the ocean, due to intense salt spray and wind. Coalescence of coastal fog accounts for a considerable part of the trees' water needs; the northern boundary of its range is marked by groves on the Chetco River on the western fringe of the Klamath Mountains, near the California-Oregon border. The largest populations are in Redwood National and State Parks (Del Norte and Humbo
Oregon is a state in the Pacific Northwest region on the West Coast of the United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho; the parallel 42 ° north delineates the southern boundary with Nevada. Oregon is one of only four states of the continental United States to have a coastline on the Pacific Ocean. Oregon was inhabited by many indigenous tribes before Western traders and settlers arrived. An autonomous government was formed in the Oregon Country in 1843 before the Oregon Territory was created in 1848. Oregon became the 33rd state on February 14, 1859. Today, at 98,000 square miles, Oregon is the ninth largest and, with a population of 4 million, 27th most populous U. S. state. The capital, Salem, is the second most populous city in Oregon, with 169,798 residents. Portland, with 647,805, ranks as the 26th among U. S. cities. The Portland metropolitan area, which includes the city of Vancouver, Washington, to the north, ranks the 25th largest metro area in the nation, with a population of 2,453,168.
Oregon is one of the most geographically diverse states in the U. S. marked by volcanoes, abundant bodies of water, dense evergreen and mixed forests, as well as high deserts and semi-arid shrublands. At 11,249 feet, Mount Hood, a stratovolcano, is the state's highest point. Oregon's only national park, Crater Lake National Park, comprises the caldera surrounding Crater Lake, the deepest lake in the United States; the state is home to the single largest organism in the world, Armillaria ostoyae, a fungus that runs beneath 2,200 acres of the Malheur National Forest. Because of its diverse landscapes and waterways, Oregon's economy is powered by various forms of agriculture and hydroelectric power. Oregon is the top timber producer of the contiguous United States, the timber industry dominated the state's economy in the 20th century. Technology is another one of Oregon's major economic forces, beginning in the 1970s with the establishment of the Silicon Forest and the expansion of Tektronix and Intel.
Sportswear company Nike, Inc. headquartered in Beaverton, is the state's largest public corporation with an annual revenue of $30.6 billion. The earliest evidence of the name Oregon has Spanish origins; the term "orejón" comes from the historical chronicle Relación de la Alta y Baja California written by the new Spaniard Rodrigo Montezuma and made reference to the Columbia River when the Spanish explorers penetrated into the actual North American territory that became part of the Viceroyalty of New Spain. This chronicle is the first topographical and linguistic source with respect to the place name Oregon. There are two other sources with Spanish origins, such as the name Oregano, which grows in the southern part of the region, it is most probable that the American territory was named by the Spaniards, as there are some populations in Spain such as "Arroyo del Oregón" considering that the individualization in Spanish language "El Orejón" with the mutation of the letter "g" instead of "j". Another early use of the name, spelled Ouragon, was in a 1765 petition by Major Robert Rogers to the Kingdom of Great Britain.
The term referred to the then-mythical River of the West. By 1778, the spelling had shifted to Oregon. In his 1765 petition, Rogers wrote: The rout...is from the Great Lakes towards the Head of the Mississippi, from thence to the River called by the Indians Ouragon... One theory is that the name comes from the French word ouragan, applied to the River of the West based on Native American tales of powerful Chinook winds on the lower Columbia River, or from firsthand French experience with the Chinook winds of the Great Plains. At the time, the River of the West was thought to rise in western Minnesota and flow west through the Great Plains. Joaquin Miller explained in Sunset magazine, in 1904, how Oregon's name was derived: The name, Oregon, is rounded down phonetically, from Ouve água—Oragua, Or-a-gon, Oregon—given by the same Portuguese navigator that named the Farallones after his first officer, it in a large way, means cascades:'Hear the waters.' You should steam up the Columbia and hear and feel the waters falling out of the clouds of Mount Hood to understand the full meaning of the name Ouve a água, Oregon.
Another account, endorsed as the "most plausible explanation" in the book Oregon Geographic Names, was advanced by George R. Stewart in a 1944 article in American Speech. According to Stewart, the name came from an engraver's error in a French map published in the early 18th century, on which the Ouisiconsink River was spelled "Ouaricon-sint", broken on two lines with the -sint below, so there appeared to be a river flowing to the west named "Ouaricon". According to the Oregon Tourism Commission, present-day Oregonians pronounce the state's name as "or-uh-gun, never or-ee-gone". After being drafted by the Detroit Lions in 2002, former Oregon Ducks quarterback Joey Harrington distributed "Orygun" stickers to members of the media as a reminder of how to pronounce the name of his home state; the stickers are sold by the University of Oregon Bookstore. Oregon is 295 miles north to south at longest distance, 395 miles east to west. With an area of 98,381 square miles, Oregon is larger than the United Kingdom.
It is the ninth largest state in the United States. Oregon's highest point is the summit of Mount Hood, at 11,249 feet, its lowest point is the sea level of the Pacific Ocean along the Oregon Coas
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic material, a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves, it conveys water and nutrients between the leaves, other growing tissues, the roots. Wood may refer to other plant materials with comparable properties, to material engineered from wood, or wood chips or fiber. Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons and paper. More it emerged as a feedstock for the production of purified cellulose and its derivatives, such as cellophane and cellulose acetate.
As of 2005, the growing stock of forests worldwide was about 434 billion cubic meters, 47% of, commercial. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as a source of renewable energy. In 1991 3.5 billion cubic meters of wood were harvested. Dominant uses were for building construction. A 2011 discovery in the Canadian province of New Brunswick yielded the earliest known plants to have grown wood 395 to 400 million years ago. Wood can be dated by carbon dating and in some species by dendrochronology to determine when a wooden object was created. People have used wood for thousands of years for many purposes, including as a fuel or as a construction material for making houses, weapons, packaging and paper. Known constructions using wood date back ten thousand years. Buildings like the European Neolithic long house were made of wood. Recent use of wood has been enhanced by the addition of bronze into construction; the year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at the time a tree was cut.
Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, roots. This process is known as secondary growth; these cells go on to form thickened secondary cell walls, composed of cellulose and lignin. Where the differences between the four seasons are distinct, e.g. New Zealand, growth can occur in a discrete annual or seasonal pattern, leading to growth rings. If the distinctiveness between seasons is annual, these growth rings are referred to as annual rings. Where there is little seasonal difference growth rings are to be indistinct or absent. If the bark of the tree has been removed in a particular area, the rings will be deformed as the plant overgrows the scar. If there are differences within a growth ring the part of a growth ring nearest the center of the tree, formed early in the growing season when growth is rapid, is composed of wider elements.
It is lighter in color than that near the outer portion of the ring, is known as earlywood or springwood. The outer portion formed in the season is known as the latewood or summerwood. However, there are major differences, depending on the kind of wood; as a tree grows, lower branches die, their bases may become overgrown and enclosed by subsequent layers of trunk wood, forming a type of imperfection known as a knot. The dead branch may not be attached to the trunk wood except at its base, can drop out after the tree has been sawn into boards. Knots affect the technical properties of the wood reducing the local strength and increasing the tendency for splitting along the wood grain, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a circular "solid" piece of wood around which the grain of the rest of the wood "flows". Within a knot, the direction of the wood is up to 90 degrees different from the grain direction of the regular wood. In the tree a knot is either the base of a dormant bud.
A knot is conical in shape with the inner tip at the point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud. In grading lumber and structural timber, knots are classified according to their form, size and the firmness with which they are held in place; this firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow. Knots materially affect cracking and warping, ease in working, cleavability of timber, they are defects which weaken timber and lower its value for structural purposes where strength is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than when under load along the grain and/or compression; the extent to which knots affect the strength of a beam depends upon their position, size and condition. A knot on the upper side is compressed. If there is a season check
In economics, cargo or freight refers to goods or produce being conveyed – for commercial gain – by water, air or land. Cargo was a shipload. Cargo now covers all types of freight, including that carried by train, truck, or intermodal container; the term cargo is used in case of goods in the cold-chain, because the perishable inventory is always in transit towards a final end-use when it is held in cold storage or other similar climate-controlled facility. Multi-modal container units, designed as reusable carriers to facilitate unit load handling of the goods contained, are referred to as cargo, specially by shipping lines and logistics operators. Aircraft ULD boxes are documented as cargo, with associated packing list of the items contained within; when empty containers are shipped each unit is documented as a cargo and when goods are stored within, the contents are termed as containerised cargo. Seaport terminals handle a wide range of maritime cargo. Automobiles are handled at many ports and are carried on specialized roll-on/roll-off ships.
Break bulk cargo is material stacked on pallets and lifted into and out of the hold of a vessel by cranes on the dock or aboard the ship itself. The volume of break bulk cargo has declined worldwide as containerization has grown. One way to secure break bulk and freight in intermodal containers is by using Dunnage Bags. Bulk cargo, such as salt, oil and scrap metal, is defined as commodities that are neither on pallets nor in containers. Bulk cargoes are not handled as individual pieces, the way heavy-lift and project cargoes are. Alumina, gypsum and wood chips, for instance, are bulk cargoes. Neo-bulk cargo comprises individual units that are counted as they are loaded and unloaded, in contrast to bulk cargo, not counted, but that are not containerized. Containers are the fastest growing cargo category at most ports worldwide. Containerized cargo includes everything from auto parts and manufacturing components to shoes and toys to frozen meat and seafood. Project cargo and the heavy lift cargo include items like manufacturing equipment, air conditioners, factory components, wind turbines, military equipment, any other oversized or overweight cargo, too big or too heavy to fit into a container.
Air cargo known as air freight, is collected by firms from shippers and delivered to customers. Aircraft were first used for carrying mail as cargo in 1911. Manufacturers started designing aircraft for other types of freight as well. There are many commercial aircraft suitable for carrying cargo such as the Boeing 747 and the bigger An‑124, purposely built for easy conversion into a cargo aircraft; such large aircraft employ quick-loading containers known as unit load devices, much like containerized cargo ships. The ULDs are located in the front section of the aircraft. Most nations own and utilize large numbers of military cargo aircraft such as the C‑17 Globemaster III for logistical needs. Popular commercial aircraft transformed to a cargo aircraft such as Saab 340A is designed for high revenue and profitability in short / medium haul operations. Trains are capable of transporting a large number of containers. Trains are used for the transportation of water, grain, steel and coal, they are used because they can carry a large amount and have a direct route to the destination.
Under the right circumstances, freight transport by rail is more economic and energy efficient than by road when carried in bulk or over long distances. The main disadvantage of rail freight is its lack of flexibility. For this reason, rail has lost much of the freight business to road transport. Rail freight is subject to transshipment costs, since it must be transferred from one mode of transportation to another. Practices such as containerization aim at minimizing these costs; when transporting point-to-point bulk loads such as cement or grain, with specialised bulk handling facilities at the rail sidings, rail mode of transport remains the most convenient and preferred option. Many governments are trying to encourage shippers to use trains more because of the environmental benefits. Many firms, like Parcelforce, R+L Carriers transport all types of cargo by road. Delivering everything from letters to houses to cargo containers, these firms offer fast, sometimes same-day, delivery. A good example of road cargo is food, as supermarkets require deliveries daily to replenish their shelves with goods.
Retailers and manufacturers of all kinds rely upon delivery trucks, be they full size semi trucks or smaller delivery vans. These smaller road haulage companies strive for the best routes and prices to ship out their products. Indeed, the level of commercial freight transported by smaller businesses is a good barometer of healthy economic development as it is these types of vehicles that move and transport anything, including couriers transporting parcel and mail. You can see the different weights of vehicles that are used to move cargo around. Freight is organized into various shipment categories before it is transported. An item's category is determined by: the type of item being carried. For example, a kettle could fit into the category'household goods'. How large the shipment is, in terms of both item size and quantity. How long the item for delivery will be in transit. Shipments are categorized as household goods, express and freight shipments: Household goods include furniture and similar items.
Small business or personal items like envelopes are considered overnight expres
San Francisco Bay
San Francisco Bay is a shallow estuary in the US state of California. It is surrounded by a contiguous region known as the San Francisco Bay Area, is dominated by the large cities of San Jose, San Francisco and Oakland. San Francisco Bay drains water from 40 percent of California. Water from the Sacramento and San Joaquin rivers, from the Sierra Nevada mountains, flow into Suisun Bay, which travels through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay; the Guadalupe River enters the bay at its southernmost point in San Jose. The Guadalupe drains water from the Santa Cruz mountains and Hamilton Mountain ranges in southernmost San Jose, it enters the bay at the town of Alviso. It connects to the Pacific Ocean via the Golden Gate strait. However, this entire group of interconnected bays is called the San Francisco Bay; the bay was designated a Ramsar Wetland of International Importance on February 2, 2012. The bay covers somewhere between 400 and 1,600 square miles, depending on which sub-bays, wetlands, so on are included in the measurement.
The main part of the bay measures three to twelve miles wide east-to-west and somewhere between 48 miles 1 and 60 miles 2 north-to-south. It is the largest Pacific estuary in the Americas; the bay was navigable as far south as San Jose until the 1850s, when hydraulic mining released massive amounts of sediment from the rivers that settled in those parts of the bay that had little or no current. Wetlands and inlets were deliberately filled in, reducing the Bay's size since the mid-19th century by as much as one third. Large areas of wetlands have been restored, further confusing the issue of the Bay's size. Despite its value as a waterway and harbor, many thousands of acres of marshy wetlands at the edges of the bay were, for many years, considered wasted space; as a result, soil excavated for building projects or dredged from channels was dumped onto the wetlands and other parts of the bay as landfill. From the mid-19th century through the late 20th century, more than a third of the original bay was filled and built on.
The deep, damp soil in these areas is subject to soil liquefaction during earthquakes, most of the major damage close to the Bay in the Loma Prieta earthquake of 1989 occurred to structures on these areas. The Marina District of San Francisco, hard hit by the 1989 earthquake, was built on fill, placed there for the Panama-Pacific International Exposition, although liquefaction did not occur on a large scale. In the 1990s, San Francisco International Airport proposed filling in hundreds more acres to extend its overcrowded international runways in exchange for purchasing other parts of the bay and converting them back to wetlands; the idea was, remains, controversial. There are five large islands in San Francisco Bay. Alameda, the largest island, was created when a shipping lane was cut to form the Port of Oakland in 1901, it is now a suburban community. Angel Island was known as "Ellis Island West" because it served as the entry point for immigrants from East Asia, it is now a state park accessible by ferry.
Mountainous Yerba Buena Island is pierced by a tunnel linking the east and west spans of the San Francisco–Oakland Bay Bridge. Attached to the north is the artificial and flat Treasure Island, site of the 1939 Golden Gate International Exposition. From the Second World War until the 1990s, both islands served as military bases and are now being redeveloped. Isolated in the center of the Bay is Alcatraz, the site of the famous federal penitentiary; the federal prison on Alcatraz Island no longer functions, but the complex is a popular tourist site. Despite its name, Mare Island in the northern part of the bay is a peninsula rather than an island. San Francisco Bay is thought to represent a down-warping of the Earth's crust between the San Andreas Fault to the west and the Hayward Fault to the east, though the precise nature of this remains under study. About 560,000 years ago, a tectonic shift caused the large inland Lake Corcoran to spill out the central valley and through the Carquinez Strait, carving out sediment and forming canyons in what is now the northern part of the San Francisco Bay and Golden Gate strait.
Until the last ice age, the basin, now filled by the San Francisco Bay was a large linear valley with small hills, similar to most of the valleys of the Coast Ranges. As the great ice sheets began to melt, around 11,000 years ago, the sea level started to rise. By 5000 BC the sea level rose 300 feet; the valley become a bay, the small hills became islands. From 15,000 – 10,000 years ago, the Ohlone tribe inhabited the area, now the San Francisco Bay; the natives were displaced 5,000 years ago as the bay filled with water due to the rising sea level at the end of the ice age. The first European to see San Francisco Bay is N. de Morena, left at New Albion at Drakes Bay in Marin County, California by Sir Francis Drake in 1579 and walked to Mexico. The first recorded European discovery of San Francisco Bay was on November 4, 1769 when Spanish explorer Gaspar de Portolà, unable to find the port of Monterey, continued north close to what is now Pacifica and reached the summit of the 1,200-foot-high Sweeney Ridge, now marked as the place where he first sighted San Francisco Bay.
Portolá and his party did not realize what they had discovered, thinking they had arrived at a large arm of what is now called Drakes Bay. At the time, Drakes Bay went by the name Bahia de San
A flood is an overflow of water that submerges land, dry. In the sense of "flowing water", the word may be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rainwater on saturated ground in an areal flood. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, these changes in size are unlikely to be considered significant unless they flood property or drown domestic animals. Floods can occur in rivers when the flow rate exceeds the capacity of the river channel at bends or meanders in the waterway. Floods cause damage to homes and businesses if they are in the natural flood plains of rivers.
While riverine flood damage can be eliminated by moving away from rivers and other bodies of water, people have traditionally lived and worked by rivers because the land is flat and fertile and because rivers provide easy travel and access to commerce and industry. Some floods develop while others such as flash floods can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community, or large, affecting entire river basins; the word "flood" comes from a word common to Germanic languages. Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more than it can either infiltrate or run off; the excess accumulates in place, sometimes to hazardous depths. Surface soil can become saturated, which stops infiltration, where the water table is shallow, such as a floodplain, or from intense rain from one or a series of storms. Infiltration is slow to negligible through frozen ground, concrete, paving, or roofs.
Areal flooding begins in flat areas like floodplains and in local depressions not connected to a stream channel, because the velocity of overland flow depends on the surface slope. Endorheic basins may experience areal flooding during periods when precipitation exceeds evaporation. Floods occur in all types of river and stream channels, from the smallest ephemeral streams in humid zones to normally-dry channels in arid climates to the world's largest rivers; when overland flow occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load. Localized flooding may be caused or exacerbated by drainage obstructions such as landslides, debris, or beaver dams. Slow-rising floods most occur in large rivers with large catchment areas; the increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be intense in smaller areas of those basins.
Rapid flooding events, including flash floods, more occur on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, or normally-dry channels. The cause may be localized convective precipitation or sudden release from an upstream impoundment created behind a dam, landslide, or glacier. In one instance, a flash flood killed eight people enjoying the water on a Sunday afternoon at a popular waterfall in a narrow canyon. Without any observed rainfall, the flow rate increased from about 50 to 1,500 cubic feet per second in just one minute. Two larger floods occurred at the same site within a week, but no one was at the waterfall on those days; the deadly flood resulted from a thunderstorm over part of the drainage basin, where steep, bare rock slopes are common and the thin soil was saturated. Flash floods are the most common flood type in normally-dry channels in arid zones, known as arroyos in the southwest United States and many other names elsewhere.
In that setting, the first flood water to arrive is depleted. The leading edge of the flood thus advances more than and higher flows; as a result, the rising limb of the hydrograph becomes quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant. Flooding in estuaries is caused by a combination of sea tidal surges caused by winds and low barometric pressure, they may be exacerbated by high upstream river flow. Coastal areas may be flooded by storm events at sea, resulting in waves over-topping defenses or in severe cases by tsunami or tropical cyclones. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category. Research from the NHC explains: "Storm surge is an abnormal rise of water generated by a storm and above the predicted astronomical tides. Storm surge should not be confused with storm tide, defined as the water level rise due to the combination of storm surge and the astronomical tide.
This rise in water level can cause extreme flooding in coastal areas when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases." Urban flooding is the inundation of land or property in a built environment in more densely populated areas, caused by rainfall overwhelmi