Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that
Hornby Island of British Columbia, Canada, is a Salish Sea island located near Vancouver Island's Comox Valley. A small community of 958 residents, Hornby is home to many artists, retired professionals, small business owners, remote workers, young families who share a love of rural island life. Over the past 30 years, the island has become a coveted destination and its population quadruples in size during the summer months; the shoulder seasons are a preferred time for hiking, mountain biking, marine activities and retreats. Most people reach the island by ferries from Vancouver Island. A growing number of private boats visit through mooring at the Ford Cove Marina or anchoring at Tribune Bay; the closest airport is Comox Valley Airport in Comox, which provides regional and international service. The primary destinations on Hornby are Tribune Bay Provincial Park, Helliwell Provincial Park, Ford's Cove, Heron Rocks and Whaling Station Bay; the island is a popular mountain biking destination, with a variety of designated trails in Mount Geoffrey Regional Nature Park, Mount Geoffrey Escarpment Provincial Park and Crown Land.
The total land area is 29.92 square kilometres. The island is geographically distinctive as it was formed by post-glacial rebound with the retreat of the last ice age. Before the arrival of European settlers, the island was inhabited by the Pentlatch, a Coast Salish First Nations band who called the Island Ja-dai-aich, meaning The Outer Island; the island was found and named Isla de Lerena during the 1791 voyage of the Spanish ship Santa Saturnina, under Juan Carrasco and José María Narváez. The name honors the Spanish Finance Minister, Don Pedro López de Lerena, who supported the movement of Spanish Ships over there. In 1850 the British renamed it after Rear Admiral Phipps Hornby Commander of the Pacific Station. Hornby Island is covered by mixed forest dominated by Douglas-fir. Western red cedar, western hemlock, grand fir and lodgepole pine are the other large conifers present; the smaller Pacific yew is scattered in the understorey. The arbutus, a broadleaf evergreen species, is plentiful. Broadleaf deciduous trees include bigleaf maple, red alder, black cottonwood, Pacific flowering dogwood and several species of willow.
Populations of Garry oak occur at Helliwell Provincial Park. Only about 260 acres of undisturbed stands for older forest have been identified on Hornby Island, which amount to 3.5% of the island's area. There are 1,330 acres of older second-growth stands on the island, which amount to 19% of the island; the island's soils have developed from marine deposits of variable texture, except for the higher elevations and steeper slopes where weathered clastic sedimentary rock provides the parent material. Most of Hornby's soils are sandy or gravelly, but some deep black loams occur in the northwestern part and many of the sands at the southern end have loam-textured topsoils. Podzols are common and the bleached sand grains associated with their eluvial horizons lend a salt-and-pepper appearance to many forest trails. In most cases, the E is not thick and may be discontinuous. On this account, the soils were classified as Brown Podzolic in a soil survey published in 1959. All of the island's soils are acidic in their natural state except for those which have developed on shoreline shell middens.
Fossil collectors have found Baculite fossils at Boulder Point on Hornby Island. A new species of pterosaur called Gwawinapterus beardi was identified based on a fossil found on a beach on Hornby Island. Hornby Island Community Website Hornby Island Residents' & Ratepayers' Association 2006 census data Helliwell Provincial Park Tribune Bay Provincial Park
Strait of Georgia
The Strait of Georgia or the Georgia Strait is an arm of the Pacific Ocean between Vancouver Island and the extreme southwestern mainland coast of British Columbia and the extreme northwestern mainland coast of Washington, United States. It is 240 kilometres long and varies in width from 20 to 58 kilometres. Along with the Strait of Juan de Fuca and Puget Sound, it is a constituent part of the Salish Sea. Archipelagos and narrow channels mark each end of the Strait of Georgia, the Gulf Islands and San Juan Islands in the south, the Discovery Islands in the north; the main channels to the south are Boundary Pass, Haro Strait and Rosario Strait, which connect the Strait of Georgia to the Strait of Juan de Fuca. In the north, Discovery Passage is the main channel connecting the Strait of Georgia to Johnstone Strait; the strait is a major navigation channel on the west coast of North America, owing to the presence of the port of Vancouver, due to its role as the southern entrance to the intracoastal route known as the Inside Passage.
The United States Geological Survey defines the southern boundary of the Strait of Georgia as a line running from East Point on Saturna Island to Patos Island, Sucia Island, Matia Island to Point Migley on Lummi Island. This line touches the northern edges of Rosario Strait, which leads south to the Strait of Juan de Fuca, Boundary Pass, which leads south to Haro Strait and the Strait of Juan de Fuca; the mean depth of the Strait of Georgia is 157 metres, with a maximum depth of 448 metres. Its surface area is 6,800 square kilometres; the Fraser River accounts for 80 percent of the fresh water entering the strait. Water circulates in the strait in a general counterclockwise direction; the term "Gulf of Georgia" includes waters other than the Georgia Strait proper, such as the inter-insular straits and channels of the Gulf Islands, may refer to communities on the shore of southern Vancouver Island. As defined by George Vancouver in 1792, the Gulf of Georgia included all the inland waters beyond the eastern end of the Strait of Juan de Fuca, including Puget Sound, Bellingham Bay, the waters around the San Juan Islands, as well as the Strait of Georgia.
Several major islands are in the largest being Quadra Island and Texada Island. First Nations communities have surrounded the Strait of Georgia for thousands of years; the first European exploration of the area was undertaken by Captain Jose Maria Narvaez and Pilot Juan Carrasco of Spain in 1791. At this time Francisco de Eliza gave the strait the name "Gran Canal de Nuestra Señora del Rosario la Marinera." In 1792, it was renamed for King George III as the "Gulf of Georgia" by George Vancouver of Great Britain, during his extensive expedition along the west coast of North America. Vancouver designated the mainland in this region as New Georgia, areas farther north as New Hanover and New Bremen; the June 23, 1946 Vancouver Island earthquake shocked the Strait of Georgia region, causing the bottom of Deep Bay to sink between 3 and 26 m. The two busiest routes of the BC Ferries system cross the strait, between Tsawwassen and Swartz Bay and between Horseshoe Bay and Nanaimo; the Strait of Georgia is known as a premier scuba whale watching location.
In 1967, the Georgia Strait inspired the name of Vancouver's alternative newspaper, The Georgia Straight, which has published continuously since. Towns and cities on the strait include Campbell River, Comox, Qualicum Beach, Parksville and Nanaimo on the western shore, as well as Powell River, Sechelt and Greater Vancouver on the east. Across the border in the United States, Bellingham and other communities lie on the eastern shore. Other settlements on Vancouver Island and the mainland are separated from Georgia Strait itself by islands and lesser straits but are spoken of as being in the Strait of Georgia region. A controversial idea has existed since 1872 of a bridge connecting Vancouver Island to the British Columbia mainland; the first idea was to cross Seymour Narrows at Menzies Bay with a rail bridge for the then-proposed Canadian Pacific Railway to link Victoria, via Bute Inlet and the Yellowhead Pass, with the rest of Canada. Proposals have focussed on bridging the Strait of Georgia itself, much wider than Seymour Narrows.
A proposed modern road bridge connecting Greater Vancouver to Vancouver Island in the manner of the Chesapeake Bay Bridge Tunnel, has been discussed for decades since the commencement of service by BC Ferries. Some crossing design suggestions include a floating submerged tunnel to allow ship traffic to move freely; the hurricane-force windstorms of Typhoon Freda in 1962 and of December 2006 call into question the safety of such a project. Proponents of the bridge argue that a reliable link to Vancouver Island from mainland British Columbia will increase tourism and growth on Vancouver Island. Opponents argue that construction of a bridge will result in further urbanization of the island and that the area's environment will be negatively affected by construction and the increase in tourism. Other potential problems are the width and depth of the strait and the soft consistency of the strait floor, as well as high seismic activity in the Vancouver Island region, the fact that the strait is used as a navigation channel.
The strait is far deeper than any bridged body of water in the world. Former B. C. cabinet minister Dr. Patrick McGeer, a research neuroscientist and a science advocate, has advanced the proposal in recent decades
Buckley Bay, British Columbia
Buckley Bay is a geographical location on the east coast of Vancouver Island, located between Union Bay to the north and Fanny Bay to the south. It is the departure point for the BC Ferries crossing of Baynes Sound to Denman Island, it is accessible from both the Old Island Highway and from Exit 101 on the newer Inland Island Highway. It has a population of 173, according to the 2006 Census
Shale is a fine-grained, clastic sedimentary rock composed of mud, a mix of flakes of clay minerals and tiny fragments of other minerals quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility, it is the most common sedimentary rock. Shale exhibits varying degrees of fissility, breaking into thin layers splintery and parallel to the otherwise indistinguishable bedding plane because of the parallel orientation of clay mineral flakes. Non-fissile rocks of similar composition but made of particles smaller than 0.06 mm are described as mudstones or claystones. Rocks with similar particle sizes but with less clay and therefore grittier are siltstones. Shales are composed of clay minerals and quartz grain, are grey. Addition of variable amounts of minor constituents alters the color of the rock. Black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment.
Black shale can be referred to as black metal. Red and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the major constituent of other mudrocks; the clay minerals represented are kaolinite and illite. Clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks in mid- to early Paleozoic shales illites predominate; the transformation of smectite to illite produces silica, calcium, magnesium and water. These released elements form authigenic quartz, calcite, ankerite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain 95 percent of the organic matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale. Black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration; the process in the rock cycle which forms shale is called compaction.
The fine particles that compose shale can remain suspended in water long after the larger particles of sand have deposited. Shales are deposited in slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains and offshore from beach sands, they can be deposited in sedimentary basins and on the continental shelf, in deep, quiet water.'Black shales' are dark, as a result of being rich in unoxidized carbon. Common in some Paleozoic and Mesozoic strata, black shales were deposited in anoxic, reducing environments, such as in stagnant water columns; some black shales contain abundant heavy metals such as molybdenum, uranium and zinc. The enriched values are of controversial origin, having been alternatively attributed to input from hydrothermal fluids during or after sedimentation or to slow accumulation from sea water over long periods of sedimentation. Fossils, animal tracks/burrows and raindrop impact craters are sometimes preserved on shale bedding surfaces.
Shales may contain concretions consisting of pyrite, apatite, or various carbonate minerals. Shales that are subject to heat and pressure of metamorphism alter into a hard, metamorphic rock known as slate. With continued increase in metamorphic grade the sequence is phyllite schist and gneiss. Before the mid-19th century, the terms slate and schist were not distinguished. In the context of underground coal mining, shale was referred to as slate well into the 20th century. Bakken Formation Barnett Shale Bearpaw Formation Burgess Shale Marcellus Formation Mazon Creek fossil beds Oil shale – Organic-rich fine-grained sedimentary rock containing kerogen Shale gas Shale gas in the United States Wheeler Shale Wianamatta Shale Media related to Shale at Wikimedia Commons
Baynes Sound is the channel between Denman Island and Vancouver Island, British Columbia, Canada. The sound is a narrow western offshoot of the Strait of Georgia that separates Vancouver Island from the mainland of British Columbia; the area is harvested by the local oyster industry, as is apparent by an abundance of oyster farms. It produces 55 % of the manila clams farmed in British Columbia; the sound is 40 km long and is 3.5 km wide at its widest point, although the average width is less than 2 km. The southern boundary lies around Chrome Island, a small island off Boyle Point, the southern tip of Denman; the northern boundary is less defined, but lies between Tree Island at the northern end of Denman and the Comox harbour. The sound is dotted with the small communities of Royston, Union Bay, Buckley Bay, Mud Bay, Fanny Bay, Deep Bay on Vancouver Island; the crossing is served by the British Columbia Ferry Services Inc. ship MV Baynes Sound Connector, between Buckley Bay and Denman Island.
Baynes Sound is named after British Rear Admiral Robert L. Baynes, who commanded the Pacific Squadron from 1857 to 1860. Baynes Sound is the home of Vancouver Island University Center for Shellfish Research's Deep Bay Marine Field Station. Baynes Sound is the safest route by boats into Comox Harbour, avoiding the shallow Comox Bar between Denman Island and the Comox Peninsula
The Gulf Islands are the islands in the Strait of Georgia, between Vancouver Island and the mainland of British Columbia, Canada. According to BC Geographical Names the name "Gulf Islands" was intended and understood to refer to the archipelago at the southern end of the Strait of Georgia—from Gabriola Island in the north to Saturna Island in the southeast and D'Arcy Island in the southwest. During the 1990s, the name began to be applied to all the islands in the Strait of Georgia, resulting in the introduction of the term "Southern Gulf Islands", which BCGNIS calls a misnomer, to distinguish the original "Gulf Islands" from the rest, which are sometimes called the "Northern Gulf Islands". BCGNIS further notes that Quadra Island is described as the "northernmost of the Gulf Islands"; the division of the Gulf Islands into two groups, the Southern and Northern Gulf Islands, is common. The dividing line is that formed by the city of Nanaimo on Vancouver Island, the mouth of the Fraser River on the mainland.
The larger populated islands are served by BC Ferries, which operates various vehicle and passenger ferries between the Gulf Islands and to terminals near the major cities of Nanaimo and Victoria on Vancouver Island as well as Vancouver on the mainland. BC Ferries distinguishes between the Northern Gulf Islands, their Northern Gulf Islands includes both Quadra Island and Cortes Island, as well as some islands far to the north, such as Malcolm Island and Cormorant Island. Natural Resources Canada maps the Gulf Islands as including the "Southern Gulf Islands", the islands of Howe Sound, along with Lasqueti Island, Hornby Island, Denman Island; the Southern Gulf Islands include hundreds of islands and islets, form part of a larger archipelago that includes the nearby San Juan Islands of the state of Washington, in the United States. The Southern Gulf Islands are best known for their artists, wineries and farms, as well as for their natural beauty. Boating, hiking and wildlife viewing are all possible in the Southern Gulf Islands.
The major Southern Gulf Islands are as follows: Galiano Island Mayne Island North and South Pender Islands Salt Spring Island Saturna Island Penelakut Island Thetis Island Valdes Island Gabriola Island The major Northern Gulf Islands are as follows: Denman Island Hornby Island Lasqueti Island Texada IslandQuadra Island is sometimes said to be part of the Gulf Islands. It is more designated as part of the Discovery Islands; this table provides an overview of the major Southern Gulf Islands: The name "Gulf Islands" comes from "Gulf of Georgia," the original term used by George Vancouver in his mapping of the southern part of the archipelago and which before the San Juan Island dispute was taken to include what have since been called the San Juan Islands. Speaking, the Strait of Georgia is only the wide, open waters of the main strait between the mainland and Vancouver Island, does not refer to the adjoining waters between the islands and Vancouver Island but has become a common misnomer for the entire Gulf, which includes waters such as Active Pass, Trincomali Channel, Sansum Narrows, Malaspina Strait.
"The Gulf" refers to all such waters collectively, to those communities and shores surrounding it. Only the term "Strait of Georgia" remains in the provincial gazette although its use as a synonym for the Gulf is unofficial, while the term Gulf of Georgia remains in current use though not in the provincial gazette; the term Salish Sea was adopted in 2010 to refer to the Strait of Georgia, the Strait of Juan de Fuca, Puget Sound, all connecting and adjoining waters. The islands and surrounding ocean are rich with ecologically diverse plants and sea life including Garry oaks, wild lilies, kelp beds and Orcas. Gulf Islands National Park Reserve of Canada was established in 2003 by Parks Canada to protect the area’s unique ecosystem; the Gulf Islands are home to one of the last remaining pockets of Garry oak ecosystems. Only about five percent of Garry oak ecosystems remain in their natural state, landing 91 of the 350 species it supports on the province's list of species at risk; the unique Mediterranean characteristics of the islands' climate supports the Garry oak ecosystem.
Garry oak ecosystems are home to more plant species, such as the camas, than any other terrestrial ecosystem in coastal B. C. and are one of Canada's most at-risk natural habitats. Today, Garry oak meadows exist in the shallow and exposed soil of valleys, rocky foothills and southern slopes—areas that the settlers of the past 150 years have found unsuitable for agriculture or development; the Garry Oak Ecosystems Recovery Team, a partnership of a number of governmental and non-governmental agencies that comprise 22 individuals, was established in 1999 after the delegates of the First International Garry Oak Ecosystem Symposium met in Victoria and declared the ecosystem endangered. Since GOERT has been working to motivate public and private restoration of the rare ecosystem and promote conservation activities. In most parts of Canada, olive trees cannot thrive. Farm owner Andrew Butt has been r