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Blue Lake Crater
Blue Lake Crater (also known as Blue Lake Maar) is a maar, or a broad, low-relief volcanic crater, in the U.S. state of Oregon. Located in Jefferson County, it consists of three overlapping craters, which hold Blue Lake. The drainage basin for Blue Lake has very steep, forested slopes and is mostly part of the explosion crater left by the volcano's eruption. The volcano lies within the Metolius River basin, which supports a wide array of plant life, large and small mammals, and more than 80 bird species. A 2009 Oregon law designated the Metolius River basin as an area of critical concern, preventing large-scale development and protecting wildlife. Despite having erupted at some point within the past 4,000 years, Blue Lake Crater is considered one of the least-known Holocene volcanoes in the Cascade volcanic arc. It forms a modest volcanic cone, its lake surrounded by a crescent-shaped, agglutinate ridge consisting of volcanic bombs. The northern side of Blue Lake Crater's rim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian. History The term ''mafic'' is a portmanteau of "magnesium" and "ferric" and was coined by Charles Whitman Cross, Joseph P. Iddings, Louis Valentine Pirsson, and Henry Stephens Washington in 1912. Cross' group had previously divided the major rock-forming minerals found in igneous rocks into ''salic'' minerals, such as quartz, feldspars, or feldspathoids, and ''femic'' minerals, such as olivine and pyroxene. However, micas and aluminium-rich amphiboles were excluded, while some calcium minerals containing little iron or magnesium, such as wollastonite or apatite, were included ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Lake In The Central Oregon Cascades (3226136915)
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. In the eight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
