Basaltic andesite is a volcanic rock containing about 55% silica. It is distinct from andesite in having a different percentage of silica content. Minerals in basaltic andesite include olivine and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America
Stargate: The Ark of Truth
Stargate: The Ark of Truth is a 2008 Canadian-American, military science fiction, direct-to-video film in the Stargate franchise, acting as a sequel to the television series Stargate SG-1. It is written and directed by Robert C. Cooper, produced by Cooper, John G. Lenic, the series' creator Brad Wright, stars its regular cast; the film is the conclusion of the Ori arc, picks up after the SG-1 series finale. However, it happens before the Stargate Atlantis third season finale; the Ark of Truth was released as a Region 1 DVD on March 11, 2008. Sky One has broadcast the film on March 24, 2008, to be followed by the Region 2 DVD release on April 28, 2008 with the Region 4 DVD release on April 9, 2008. SPACE has broadcast the film on September 13, 2008; the SciFi Channel premiered the movie on March 27, 2009. It is the first of the second one being Stargate: Continuum. While digging on Dakara, SG-1 discovers a box that they believe contains the Ark of Truth, but before they can open it, Ori soldiers arrive, led by Tomin.
Daniel tricks them into opening the box. When Tomin is ordered by a Prior to kill them, he refuses, Mitchell kills the Prior, whose powers were being blocked by the Anti-Prior device. Shocked at the death of their Prior, the Ori soldiers surrender with Tomin returning to Earth with SG-1 where he resides at the SGC for a time. Back on Earth, General Landry and Mitchell meet James Marrick, an IOA representative sent to interrogate Tomin, because the original IOA representative, Richard Woolsey is now working for the Atlantis Expedition; when Daniel Jackson realizes that the Ark is still in the Ori galaxy, Marrick is assigned to accompany them on board the Odyssey through the Supergate. In the Ori galaxy, a member of the anti-Ori resistance tells the team that according to legend, the Ark is on Celestis, the Ori capital; when SG-1 beams down to the planet, Marrick activates the Asgard computer core which alerts the Ori to the ship's location. Upon being alerted by Major Kevin Marks of what is going on, Mitchell and Carter beam back to the Odyssey and discover that Marrick has used the core to build a Replicator, intending to plant it on an Ori ship and let it spread to their entire fleet.
When Mitchell attempts to destroy it with an anti-Replicator Gun, the replicator escapes, Marrick reveals that the IOA removed that weakness from the design, although conventional weapons are sufficient to destroy individual replicators. Marrick implies that a shutdown code has been included as a failsafe, but claims he does not know what it is, he is placed in the ship's brig and falls victim to the Replicators, when they make their way into the brig, resulting in Merrick becoming a Human/Replicator hybrid. With several Ori ships approaching, Mitchell attempts to beam Daniel, Teal'c, Tomin up from the planet, but the replicator takes over the system and keeps Mitchell from doing so. With no other option, the Odyssey jumps leaving the others on the planet. Daniel finds the Ark in a set of catacombs, after several ground tremors, brings it to the surface; when the team emerges, they are ambushed by Ori warriors, Teal'c is shot in the back while the others are captured. When they are brought to the city, Vala discovers that the Ori were indeed killed by the Sangraal during the events of The Shroud.
Adria has taken over all of their power. Teal'c, walking toward the city of Celestis since he was shot, collapses due to his wound within sight of the city, he continues on to free Daniel. Morgan arrives in Daniel's cell and tells him if he can expose one Prior to the Ark, the others will be turned by a link in their staffs; this will weaken Adria enough for Morgan to stalemate her. In the meantime, a Prior arrives on Earth; when General Landry refuses to listen to him, the Apollo detects a fleet of Ori motherships waiting on the edge of the solar system. On the Odyssey, Marrick is attacked by Replicators. In the ensuing battle, Mitchell is able to disable the Replicator connection to Marrick's brain, who informs Mitchell the shut down code for the Replicators is on the other side of the crystal used to create them. Mitchell activates an explosive charge. Mitchell informs Carter; when the Ark is activated and opened, the Doci is caught by the beam and made to see that the Ori are not gods and spreads this belief to all of the Priors in the Ori galaxy and through them their followers.
With Adria now in a weakened state, Morgan is able to engage her in an eternal battle. SG-1 exposes the Prior on Earth to the Ark, transmitting the knowledge about the Ori to all of the Priors in the Milky Way, thus turning all known Priors in the Universe. In the aftermath, Tomin departs for the Ori galaxy as the new leader of his people, he and Vala agreeing that, while the Ori were liars, Origin itself has a worthwhile message. Tomin asks Vala to come with him, but Vala apologizes and says that she feels her place is with the SGC. Over Daniel's objections the Ark is taken to Area 51 for study while SG-1 prepare for another new mission through the Stargate. Ben Browder as Lieutenant Colonel Cameron Mitchell Amanda Tapping as Lieutenant Colonel Doctor Samantha Carter Christopher Judge as Teal'c Michael Shanks as Dr. Daniel Jackson Beau Bridges as Major General Henry “Hank” Landry Claudia Black as Vala Mal Doran Currie Graham as James Marrick Morena Baccarin as Adria Tim Guinee as Tomin Julian Sands as Doci Sarah Strange as Morgan le Fay Michael Beach as Colonel Abe Ellis Gary Jones as Chief Maste
A summit is a point on a surface, higher in elevation than all points adjacent to it. The topographic terms acme, apex and zenith are synonymous; the term top is used only for a mountain peak, located at some distance from the nearest point of higher elevation. For example, a big massive rock next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are considered subsummits of the higher peak, are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may refer to the highest point along a line, trail, or route; the highest summit in the world is Everest with height of 8844.43 m above sea level. The first official ascent was made by Sir Edmund Hillary, they reached the mountain`s peak in 1953. Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective; the UIAA definition of a peak is.
Otherwise, it's a subpeak. In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit. A summit climbing differs from the common mountaineering. Summit expedition requires: 1+ year of training, a good physical shape, a special gear. Although a huge part of climber’s stuff can be left and taken at the base camps or given to porters, there is a long list of personal equipment. In addition to common mountaineers’ gear, Summit climbers need to take Diamox and bottles of oxygen. There are special requirements for crampons, ice axe, rappel device, etc. Geoid Hill – Landform that extends above the surrounding terrain Nadir Summit accordance Peak finder Summit Climbing Gear List
Juan de Fuca Plate
The Juan de Fuca Plate is a tectonic plate generated from the Juan de Fuca Ridge and is subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone. It is named after the explorer of the same name. One of the smallest of Earth's tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, now subducted underneath the North American Plate; the Juan de Fuca plate system crust. This oceanic crust has been subducted under the North American plate, the Eurasian Plate. Panthalassa's oceanic plate remnants are understood to be the Juan de Fuca, Gorda and the Nazca plates, all four of which were part of the Farallon Plate; the Juan de Fuca plate is bounded on the south by the Blanco Fracture Zone, on the north by the Nootka Fault and along the west by the Pacific Plate. The Juan de Fuca plate itself has since fractured into three pieces, the name is applied to the entire plate in some references, but in others only to the central portion.
The three fragments are differentiated as such: the piece to the south is known as the Gorda Plate and the piece to the north is known as the Explorer Plate. The separate pieces are demarcated by the large offsets of the undersea spreading zone; this subducting plate system has formed the Cascade Range, the Cascade Volcanic Arc, the Pacific Ranges, along the west coast of North America from southern British Columbia to northern California. These in turn are part of the Pacific Ring of Fire, a much larger-scale volcanic feature that extends around much of the rim of the Pacific Ocean; the last megathrust earthquake at the Cascadia subduction zone was the 1700 Cascadia earthquake, estimated to have a moment magnitude of 8.7 to 9.2. Based on carbon dating of local tsunami deposits, it is inferred to have occurred around 1700. Evidence of this earthquake is seen in the ghost forest along the bank of the Copalis River in Washington; the rings of the dead trees indicate that they died around 1700, it is believed that they were killed when the earthquake occurred and sunk the ground beneath them causing the trees to be flooded by saltwater.
Japanese records indicate that a tsunami occurred in Japan on 26 January 1700, caused by this earthquake. In 2008, small earthquakes were observed within the Juan de Fuca Plate; the unusual quakes were described as "more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport". The quakes were unlike most quakes in that they did not follow the pattern of a large quake, followed by smaller aftershocks. Furthermore, they did not occur on the tectonic plate boundary, but rather in the middle of the plate; the subterranean quakes were detected on hydrophones, scientists described the sounds as similar to thunder, unlike anything recorded. The basaltic formations of the Juan de Fuca Plate could be suitable for long-term CO2 sequestration as part of a carbon capture and storage system. Injection of CO2 would lead to the formation of stable carbonates, it is estimated that 100 years of US carbon emissions could be stored securely, without risk of leakage back into the atmosphere.
Astoria Fan Cascadia Channel Geology of the Pacific Northwest Plate tectonics National Geographic on Japanese records verifying an American earthquake Cascadia tectonic history with map
Garibaldi Lake is a turquoise-coloured alpine lake in British Columbia, located 37 km north of Squamish and 19 km south of Whistler. The lake lies within Garibaldi Provincial Park, which features mountains, trails, flowers, waterfalls; the park is a wildlife protected area. Garibaldi Lake lies in a deep subalpine basin, with its surface at nearly 1,500 m above sea level and a depth exceeding 250 m, it is entirely surrounded by mountains except at its northwestern tip, with volcanoes along the north and south sides and non-volcanic peaks along the northeast and eastern shores. Lava flows from the volcanoes of Mount Price and Clinker Peak to the south blocked the ancestral valley, damming the waters of the lake behind the lava formation known as The Barrier; this lava dam is over 300 m in about 2 km wide where it impounds the lake. A series of lava outcrops along the northwestern shore of the lake form the numerous tiny Battleship Islands, several of which have been connected to the shore by simple man-made stone causeways.
The turquoise colour of the lake's water is due to glacial flour suspended in the meltwater from its two primary inflows, the large Sphinx Glacier to the east and the Sentinel Glacier to the south on the flanks of Mount Garibaldi. Throughout most of the year, outflow from Garibaldi Lake occurs only via seepage through cracks in the lava dam, with Rubble Creek appearing from springs at the base of The Barrier. During spring snowmelt, outflow is sufficient for surface drainage to occur via a shallow channel across the lava flow, into Lesser Garibaldi Lake and Barrier Lake about 1.6 km west of the main lake's shore. The unstable lava formation of The Barrier has in the past unleashed several debris flows in the area below the lake, most in 1855-56 forming a large boulder field which gives Rubble Creek its name. Concerns about the Barrier's instability due to volcanic, tectonic, or heavy rainfall activity prompted the provincial government to declare the area below it unsafe for human habitation in 1981.
This led to the evacuation of the nearby village of Garibaldi, British Columbia, the relocation of residents to new recreational subdivisions away from the hazard zone. Collapse of the barrier has been speculated upon, there have been suggestions of potential catastrophic downstream consequences, the "District of Squamish, Integrated Flood Hazard Management Plan Background Report". Concludes that there has never been any suggestion in any scientific evidence that the Barrier will collapse to the point of creating an uncontrolled release of Garibaldi Lake or cause extreme flooding in downstream neighbourhoods along the Squamish River. However, the "District of Squamish Integrated Flood Hazard Management Plan - Final Report". Notes that a large collapse of the Barrier could block the Cheakamus River increasing the possibility of a debris flood the could affect the Paradise Valley. All recreational activities in the area are governed by the regulations of Garibaldi Provincial Park. Primary access to the lake is via the 9 km long Garibaldi Lake Trail, which gains 920 m of elevation from the Rubble Creek Trailhead.
There are campgrounds and day-use shelters on the west shore of Garibaldi Lake, farther northwest at Taylor Meadows. Nearly all sites have tent platforms to protect the surrounding ecosystem. During the summer, access to the eastern end of the lake is limited, since no trails have been constructed along the steep and unstable slopes which plunge directly into the lake. During winter, the lake is frozen from late December to late April, allowing backcountry skiers and snowshoers to reach the far shore. A pair of small alpine huts are located in Sphinx Bay on the eastern shore and Sentinel Bay at the southeastern tip of the lake. Cascade Volcanoes Garibaldi Lake volcanic field Garibaldi Volcanic Belt Garibaldi Provincial Park Mathews, W. H.. "Physical limnology and sedimentation in a glacial lake ". Geological Society of America Bulletin. 67: 537–552. Bibcode:1956GSAB...67..537M. Doi:10.1130/0016-7606672.0. CO. Mathews, W. H.. "Ice-dammed lavas from Clinker Mountain, southwestern British Columbia". American Journal of Science.
250: 553–565. Bibcode:1952AmJS..250..553M. Doi:10.2475/ajs.250.8.553. Moore, D. P.. "The Rubble Creek landslide, southwestern British Columbia". Canadian Journal of Earth Sciences. 15: 1039–1052. Bibcode:1978CaJES..15.1039M. Doi:10.1139/e78-112. Mathews, William H.. Garibaldi Geology: A popular guide to the geology of the Garibaldi Lake area. Geological Association of Canada. Mathews, Bill. Roadside Geology of Southern British Columbia. Mountain Press Publishing Company. ISBN 0-87842-503-9. Wood, Charles A.. Volcanoes of North America. Cambridge University Press. ISBN 0-521-43811-X. Harris, Stephen L.. Fire Mountains of the West: The Cascade and Mono Lake Volcanoes. Mountain Press Publishing Company. ISBN 0-87842-511-X. BC Parks: Garibaldi Provincial Park LiveTrails: Garibaldi Lake Outdoor Vancouver: Garibaldi Lake Hiking Trail District of Squamish: Integrated Flood Hazard Management Plan Google Earth view
The Explorer Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada and is subducted under the North American Plate. Along with the Juan De Fuca Plate and Gorda Plate, the Explorer Plate is a remnant of the ancient Farallon Plate, subducted under the North American Plate; the Explorer Plate separated from the Juan De Fuca Plate 4 million years ago. In its smoother, southern half, the average depth of the Explorer plate is 2,400 metres and rises up in its northern half to a variable basin between 1,400 metres and 2,200 metres in depth; the eastern boundary of the Explorer Plate is being subducted under the North American Plate. The southern boundary is a collection of transform faults, the Sovanco Fracture Zone, separating the Explorer Plate from the Pacific Plate. To the southeast is another transform boundary, the Nootka Fault, which separates the Explorer Plate from the Juan de Fuca Plate and forms a triple junction with the North American Plate.
To the northwest is a divergent boundary with the Pacific Plate forming the Explorer Ridge, the Winona Basin located within the northwest boundaries and the Pacific continental shelf. The Queen Charlotte triple junction is located where the Pacific Plate and North American Plate meets with the Explorer Plate. Upon breaking apart 4 million years ago, the Juan De Fuca Plate continued moving northeast at 26 mm/year while the Explorer Plate's velocity changed, stalling or moving north up to 20 mm/year; the Nootka Fault boundary between the Juan De Fuca Plate and the Explorer Plate has varied in length and direction since their separation. The formation of the Nookta Fault and the shearing of plate boundaries has caused a clockwise rotation, reorienting the Sovanco Fracture Zone northwards along the North American Plate and slowing the Explorer Plate’s subduction; the Sovanco Fracture Zone originated as a spreading center offset more than 7 million years ago which show southward movement from the influence of the Explorer ridge and results in uneven spreading eastward unto the Explorer Plate.
The subducted portion of the plate extends downward to more than 300 km depth, laterally as far as mainland Canada. The relative buoyancy of the subducting plate and the underlying mantle may be inhibiting the Explorer Plate’s ability to descend further into the mantle. There is an ongoing debate regarding the process of subduction of the Explorer Plate and how the boundary between the Explorer plate and the North American Plate are defined: The Explorer Plate has stopped and may accrete, fusing with the North American plate as the subduction has stopped and will become a plate boundary between the North American Plate and Pacific Plate rather than continuing its subduction; the Explorer Plate consists of two parts with half being fused to the North American Plate and the other half remaining a microplate system. The Explorer Plate has slowed to a terminal speed of 20 mm/year, will continue until the entire plate is subducted; as a part of the Pacific Ring of Fire, the Explorer Plate has a high level of seismic activity.
However, the activity consists of low-magnitude events. The Explorer Plate is the most seismically active area of Canada, but is anomalous as a subduction zone since most of the seismic activity occurs around the plate's perimeter rather than at the subduction interface. Events are centered around the southern and north-western areas where the borders of the plate are in contact with other plates, however the newer ocean crust created at Explorer ridge and Juan de Fuca ridge reduces the rigidity of the region and contributes to the low-magnitude of events in the region. Geology of the Pacific Northwest Cascadia tectonic history
Magma is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, evidence of magmatism has been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may contain suspended crystals and gas bubbles. Magma is produced by melting of the mantle and/or the crust at various tectonic settings, including subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During their storage in the crust, magma compositions may be modified by fractional crystallization, contamination with crustal melts, magma mixing, degassing. Following their ascent through the crust, magmas may feed a volcano or solidify underground to form an intrusion. While the study of magma has relied on observing magma in the form of lava flows, magma has been encountered in situ three times during geothermal drilling projects—twice in Iceland, once in Hawaii.
Most magmatic liquids are rich in silica. Silicate melts are composed of silicon, aluminium, magnesium, calcium and potassium; the physical behaviours of melts depend upon their atomic structures as well as upon temperature and pressure and composition. Viscosity is a key melt property in understanding the behaviour of magmas. More silica-rich melts are more polymerized, with more linkage of silica tetrahedra, so are more viscous. Dissolution of water drastically reduces melt viscosity. Higher-temperature melts are less viscous. Speaking, more mafic magmas, such as those that form basalt, are hotter and less viscous than more silica-rich magmas, such as those that form rhyolite. Low viscosity leads to less explosive eruptions. Characteristics of several different magma types are as follows: Ultramafic SiO2 < 45% Fe–Mg > 8% up to 32%MgO Temperature: up to 1500°C Viscosity: Very Low Eruptive behavior: gentle or explosive Distribution: divergent plate boundaries, hot spots, convergent plate boundaries.
At any given pressure and for any given composition of rock, a rise in temperature past the solidus will cause melting. Within the solid earth, the temperature of a rock is controlled by the geothermal gradient and the radioactive decay within the rock; the geothermal gradient averages about 25 °C/km with a wide range from a low of 5–10 °C/km within oceanic trenches and subduction zones to 30–80 °C/km under mid-ocean ridges and volcanic arc environments. It is very difficult to change the bulk composition of a large mass of rock, so composition is the basic control on whether a rock will melt at any given temperature and pressure; the composition of a rock may be considered to include volatile phases such as water and carbon dioxide. The presence of volatile phases in a rock under pressure can stabilize a melt fraction; the presence of 0.8% water may reduce the temperature of melting by as much as 100 °C. Conversely, the loss of water and volatiles from a magma may cause it to freeze or solidify.
A major portion of all magma is silica, a compound of silicon and oxygen. Magma contains gases, which expand as the magma rises. Magma, high in silica resists flowing, so expanding gases are trapped in it. Pressure builds up until the gases blast out in a dangerous explosion. Magma, poor in silica flows so gas bubbles move up through it and escape gently. Melting of solid rocks to form magma is controlled by three physical parameters: temperature and composition; the most common mechanisms of magma generation in the mantle are decompression melting and lowering of the solidus. Mechanisms are discussed further in the entry for igneous rock; when rocks melt, they do so and because most rocks are made of several minerals, which all have different melting points. As a rock melts, for example, its volume changes; when enough rock is melted, the small globules of melt soften the rock. Under pressure within the earth, as little as a fraction of a percent of partial melting may be sufficient to cause melt to be squeezed from its source.
Melts can stay in place long enough to melt to 20% or 35%, but rocks are melted in excess of 50%, because the melted rock mass becomes a crystal-and-melt mush tha