View allAll Photos Tagged METAMORPHIC
The Pre-Cambrian granite gneiss in this road cut along the Chief Joseph Highway near Swamp Lake Fen in Shoshone National Forest is 2.8-3.2 billion years old. Gneiss (pronounced like nice) is a foliated metamorphic rock identified by its bands and lenses of varying composition. When that composition is similiar to the igneous rock granite, it is called granite gneiss or granitic gneiss.
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About 1,800 million years (Ma) ago, a sedimentary conglomerate with round pebbles was subducted into an oceanic trench, transforming it into a metamorphic phyllite. During this process, the pebbles were flattened out into lens shaped pancakes, sometimes less than 0.5cm think and over 20cm in diameter. Seen here in cross section, some of the larger pebbles are still lens shaped with tapered corners. The dark red pebbles are hematite (deposited as Banded Iron Formation, BIF) Size approx 20 by 30 cm. Prescott Heights AZ, Center for Natural History
Parking lot along the S. Platte River Road. I assume most of these well rounded metamorphic boulders were hauled out of the river nearby and not trucked very far.
Tiger's eye (also called Tigers eye or Tiger eye) is a chatoyant gemstone that is usually a metamorphic rock that is a golden to red-brown color, with a silky luster. A member of the quartz group, it is a classic example of pseudomorphous replacement by silica of fibrous crocidolite (blue asbestos). An incompletely silicified blue variant is called Hawk's eye.
frozen in distilled water
The dark amphibolites and schists belong to an metamorphic-igneous complex of Archean age, that is exposed in Wind River Canyon north of Shoshone, Wyoming. These metamorphic rocks lie on the foot wall of the Boysen Fault (a normal fault) whose trace runs along the foot of the cliff in the foreground of the photo,
This location was the sight of the original Boysen Dam. Built in 1908 by a Dutch immigrant, Asmus Boysen, the dam supplied water and power to his copper and gold mines up on nearby Copper Mountain. Boysen was wealthy, a miner, prospector, businessman, entrepreneur, and most of all a visionary ( some say dreamer). But in this case things didn’t go as Boysen planned. The railroad planned to pass through the canyon by the dam, The rising water behind the small dam threatened to flood their tracks. In 1908 as the dam was completed, the railroad filed suit in court that same year. In 1911 the CB&O railroad was built through the canyon. In that same year the power plant started providing electricity to Boysen’s mines as well as the towns of Shoshoni and Riverton to the south. But that didn’t last very long. in 1915, The Wyoming Supreme Court ruled that the dam’s super structure had to be removed. That made the dam smaller and power generation much less profitable. Then in 1923 a major flood filled the plant with silt and all operations ceased. Mining declined, law suits continued, and finally Mr. Boysen lost his fortune in the venture. He died in 1938. Following all the legal wrangling the dam was finally removed in 1948 as part of a new dam project. In the 40s a new dam was built upstream 2 miles. Authorized in 1944, construction started in 1947, water storage started in 1951, power generation in 1952 and the Federal Government declared the project completed in 1953. The new Dam and Reservoir was named Boysen in honor of the dreamer who built the first dam in the Canyon. The silty bottom of the reservoir formed by Mr. Boysen’s dam is now populated with cottonwood trees and provides area for two of the campgrounds in Boysen State Park
For years The Dam Bar and Cafe by the south end of tunnel #3 just to the left of the photo. It was torn down before I can remember about the time the new dam was finished. For even a longer period, a swinging bridge crossed the river at the old dam site supported by the cables shown in the photo. My Dad would stop there and let us kids cross the rickety old bridge . It too is gone and only childhood memories remain…
Lichen atop metamorphic layers of rock. September 2018, School Trail, St. George, Maine. Rolleiflex automat tessar, tmy2 tmax 400 film in pyrocat hdc.
This type of metamorphic rock, a probable tectonic breccia, should be of interest to structural geologists and those who are curious about earth science. (Scale: the horizontal white lines (intrusive veins) are about 1 to 3 cm wide.)
The sigmoidal form (flattened-S shape) of some of the veins suggests left-lateral (sinistral) displacement. Note how veinlets inside the larger black clasts at left are following an X-pattern of brittle fractures and were likely in the process of disaggregating (fragmenting) these larger clasts. This suggests that some (or all?) of the smaller dark clasts were created by the fragmentation of larger dark clasts. Careful examination of the fabric/texture of this breccia shows that in some small areas, closely spaced clasts/fragments fit together in jigsaw fashion.
See other images of this breccia in my "Geology in building stone" album.
C. J.R. Devaney
The Scottish Highlands are made up of metamorphic and igneous rocks. Their features show that they formed during a great mountain-building episode, as plates carrying northern and southern Britain collided. Evidence from radio-active minerals in the rocks tells us that this happened between 470 and 400 million years ago.
Much more recently, the area was covered by ice during global climatic cold periods (Ice Ages). Glaciers that formed then, like glaciers in Norway or New Zealand today, had enormous erosive power because the ice contains rocks gouged from the valley floor or fallen from the mountains to either side. This ice-with-rocks scrapes along like a giant strip of very coarse sandpaper, carving out deep, U-shaped valleys like Glen Coe. Fossil evidence shows that the last glaciers in Britain melted around 10,000 years ago.
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Las Tierras Altas de Escocia están formadas por rocas metamórficas e ígneas. Sus características muestran que se formaron durante un episodio de gran activad en formación de montañas, cuando las placas que sostienen el norte y el sur de Gran Bretaña chocaron. La evidencia de minerales radioactivos en las rocas nos indica que ocurrió hace 470- 400 millones de años atrás.
En un periodo más reciente, el área fue cubierta por el hielo durante los periodos fríos de cambio climático (Edad de Hielo). Los glaciares que se formaron entonces, como los glaciares de Noruega o Nueva Zelanda, tenían un enorme poder erosivo porque el hielo contiene rocas excavadas desde el fondo del valle o caídas desde las montañas de ambos lados. Estas hielo con piedras erosionó profundamente, como una banda gigante de papel de lija, valles en forma de U como Glen Coe. La evidencia fósil muestra que los últimos glaciares en Gran Bretaña se derritieron hace 10000 años atrás.
Esta foto tiene derechos de autor. Por favor, no la utilice sin mi conocimiento y autorización. Gracias.
Please don't use this image on websites, blogs or other media without my explicit permission. © All rights reserved.
Saddlebag Lake, Eastern Sierra Nevada. Rock is mostly metamorphic except for the granite of Shepherds Crest, the pointed peak on the skyline left. The boundary of Yosemite Natl. Park passes up the right side of the light brown slope then over the summit. The upper end of Lundy Canyon lies beyond the reddish slope at the right.
The Rouge River cuts through a valley near Kilmar Quebec and a lot of exposed rock typical of the "Canadian Shield" can be found along shore. The rock was smoothed out by severe glaciation caused by the last ice age as well as the continued flow of water down the river.
A polished surface of ornamental stone, displaying well some tightly folded migmatitic gneiss. (See three similar, previously posted shots, with a scientific explanation along with the #2 image, in my "Geology in building stone" album.)
C. J.R. Devaney
Field of view is about 0.5 metre wide. The dark streaky layers are the limbs of tight V-shaped folds, with a smaller kink-like fold at lower right (it extends diagonally up to the left). The streakiness of the thinnest layers is probably a result of layer-parallel shearing and transposition ('sliding') along the foliation.
C. J.R. Devaney
Metamorphic Suite, ©2015, 4 x 4.5 x 1 inches. Polymer, Pitt pen, drawing. Single sheet coptic bound. While playing with Maggie Maggio's watercolor wash technique and some scraps, I thought the areas of color looked like rocks and layers of earth. More photos on my website
Two Lights State Park is situated on 41 acres of headland on Cape Elizabeth, Maine and offers views of Casco Bay and the Atlantic Ocean. The park's ledges are made up of metamorphic rock that first accumulated as sediment at the bottom of the ocean during the Silurian period. These cliffs break apart from erosion and storms tumbling down onto the shoreline. Print Size 13x19 inches.
I came up with this idea during geology today while not paying attention to her lecture on Metamorphic rocks and stuff...This was awkward because there were some guys working on a trailer about 20 yds from me on the other side of a thin layer of trees, one of them came over to ask what I was doing..it was just great. lol.
****This is going to be my late entry into teleidiscope week 8 "multiply" since there are two of me.
I would really like to do a print giveaway when my Facebook page reaches 500 likes, so ya'll should do that:D Also, I have form spring and would love even more distractions from school work!
Nonconformity is metamorphic or igneous rocks in contact with sedimentary strata: A nonconformity exists between sedimentary rocks and metamorphic or igneous rocks when the sedimentary rock lies above and was deposited on the pre-existing and eroded metamorphic or igneous rock.
In simple words, it's the differently colored stripes/layers of rocks that you can see here, through which the Galana river cuts.
Commentary.
We set off from Dundonnell at 08:30.
Climbing over ancient metamorphic foothills
we reached 500 feet at Loch Toll an Lochain.
A deep cleft or gully was a clear route to the mighty
arêtes of An Teallach.
We reached the knife-edge, after a very steep climb,
just north of Stob Cadha Gobhlach at 960 metres.
Edging along the stepped Old Red Sandstone and heading
north-west we reached Corrag Bhuidhe, 1,049 metres.
Down to a coll and up to the aptly named “Lord Berkeley’s Seat,” 1,030 metres.
Again, descend to a coll and up to Sgurr Fiona at 1,060 metres.
Then a mighty descent before the final climb to Bidein à Ghlas Thuill, the highest point at 1,062 metres.
Describing the route belies constant view distraction.
We sat many times just to look, take refreshments and take photographs.
The views north, east, south and west are momentous.
From Ben Wyvis in the east to Coigach and The Summer Isles in the north-west.
From the Torridon Mountains in the south-west
to the monoliths of Sutherland in the north.
This mountain is truly magnificent, and all the time,
sheer drops of 3,000 feet, to Loch Toll an Lochain
and Loch na Sealga.
We returned to basecamp by 18:30,
but, what a day!
The Buchan Gulf on northern Baffin Island, Canada, is surrounded by soaring cliffs of hard Precambrian metamorphic rock.
Omvrianós peak 3,310.4 ft (1009 m), Greece.
Outcrops of schists, gneisses, quartz & similar metamorphic rocks are scattered throughout the mountain’s cliffs, in unimaginable forms. Petrokerasa village is nearby.
Photograph inspired by the poem line:
“These stones sinking into time, how far will they drag me with them?”
—George Seferis (Mythistorema, transl. by Edmund Keeley)
The geology of Svalbard is complicated but the gist of this fascinating mountainous island archipelago goes something like this. Over geological time periods, eons, sand, mud, biological materials deposited layer upon layer somewhere around the now Caribbean Ocean, many fossils species found in the sedimentary rocks of Svalbard correspond to this. Svalbard is found at the margins of two migrating tectonic plates, the North American and Eurasian and over time the sedimentary rock layers, still being formed under shallow seas, migrated to the northeast to close to where Svalbard is today. Only after a two-stage uplift, magmatic underplating, and mantle thermal anomalies did the islands of Svalbard appear from under the waves to form the massively folded mountainous archipelago we see today. Magmatic intrusions and the immense pressure of the upheaval known as the "Tertiary Upfolding" have altered some of the rocks to form sills and dykes and metamorphic deposits. Add to this the immense glaciation that has happened throughout the ice ages and as part of Svalbard's current geological activity and the rugged, fjord intersected landscape can now be understood. Here at Fjortende Julibukta is beautiful evidence of the torrid evolution of these island.
Metamorphic rock results from the alteration of preexisting rocks in response to changing environmental conditions such as mechanical stress. The preexisting rocks may be igneous, sedimentary, or other metamorphic rocks. Metamorphism comprises changes both in mineralogy and in the fabric of the original rock. In general, these alterations are brought about either by the intrusion of hot magma into cooler surrounding rocks or by large-scale tectonic movements (e.g. earthquake) of the Earth’s plates that alter the pressure-temperature conditions of the rocks.
The surfaces where these processes are most intense and easily observed include the vast region of the Pacific margin with its seismic and volcanic activity. In general, the margins of continents and regions of mountain building are the regions where metamorphic processes proceed with intensity.
This sample of metamorphic rock was seen and photographed along the Pacific coast at Devil's Slide Trail on the San Francisco Peninsula at Pacifica, California.
During metamorphism, this migmatitic gneiss rock experienced partial melting owing to extreme heat and pressure, and was chemically (and mineralogically) segregated into felsic (light: quartz and feldspar) and mafic (dark) layers. These layers (about 1-5 cm wide/thick) were subsequently tightly folded, with probable shearing (layer-parallel deformation) and stretching along the fold limbs, resulting in discontinuous layers of uneven width/thickness.
For other similar geological explanations of this rock, see the previously posted photos in this series, in my "Geology in building stone" album.
C. J.R. Devaney
Metamorphic rock with large white-yellow feldspar crystals (several cms long), grey quartz, purple garnets, and black mafic minerals. The sub-parallel arrangement of the mafic minerals and elongate (in 2-D) feldspars define the gneissic layering.
C. J.R. Devaney
Ruins of the workings around the Homestake Mine hang on the side of Henderson Mountain in the New World Mining District outside Cooke Montana. From this view looking north from right to left over what was the upper terminal of the ore tram, Fisher Mountain, Lulu Pass, and Scotch Bonnet are visible, Geologically, the New World mining district is in the northwest trending, Cooke City structural zone that spans the Wyiming-Montana border.. About half of the area is underlain by PreCambrian schist, gneiss, and granite. The Beartooth Mountains and Wolf Peak are composed of these igneous and metamorphic rocks. To the southwest the PreCambrian rocks are overlain by Paleozoic sediments, including the Flathead quartzite, Gros Ventre shale and limestone, Gallatin limestone, Big Horn dolomite, Jefferson limestone, Three Fork shale, and Madison limestone. Eocene Absaroka Volcanics lie unconformably on Paleozoic rocks. The Fisher Mountain, The Homestake mine and other nearby mines are in the Tertiary stocks that have intruded into the overlying rocks. The intrusives are stocks of diorite, monzonite, syenite, and gabbro; and dikes and sills, of various compositions. Scotch Bonnet Mountain has mineralized zones on the edge of a diorite intrusive.
The Homestake Mine can be traced back to 1885 when Sam Mathers filed a claim on what became the mine. Two years later, Mathers shipped 30 tons of ore from the mine to a smelter in Salt Lake City. That must have been a difficult task with no railroads, and few poorly maintained roads. The Beartooth Highway to Red Lodge didn’t exist. There were only rough trails to Wyoming's Bighorn Basin which had few towns and no railroad yet. Roads through Yellowstone National Park were primative and the closest railroad near Livington Montana. Despite the difficultly transporting ore from the remote Montana mountains, he got the ore processed. The ore netted him $3,000 and encouraged him to continue work on the mine's three adits, numerous crosscuts and minor drifts. A shop and shed were constructed near the intermediate level adit. The gold and silver mine was one of 279 mining claims in the New World District and, along with the Alice E. and Daisy mines also on Henderson Mountain, was one of the most productive. A small tent camp, located below the mine may have been associated with the workings in the late 19th century. By 1894, mining at the Homestake had ceased in the wake of the Silver Purchase Act and the resulting national depression. By 1916, however, the Western Smelting and Power Company had purchased the claim, along with the Gold Dust claim, and planned extensive development of both mines. Located 700 feet below the Homestake, Gold Dust mining engineers and geologists expected to tap into the rich gold-copper veins exposed in the Homestake mine. In anticipation of the strike and the completion of the smelter in 1923, the company began construction of an aerial tram that connected the Homestake mine with the Gold Dust mine and the smelter, almost two miles away. At the time of connection with the aerial tram, the Homestake mine consisted of three adits and 700 feet of workings. Despite the predictions of the Western Smelting and Power Company planners, the ore body present in the Homestake mine was never struck by the Gold Dust miners. Both mines ceased operations by 1930. In 1948, the Parkmont Mining Company of Cooke City began a small open-cut mine on the Homestake claim and was recovering 70 tons of $11 ore daily by 1949. The open-cut was worked by a Koehring diesel shovel and a Sullivan wagon drill. By 1950, the underground workings were inaccessible
References:
deq.mt.gov/Land/abandonedmines/linkdocs/154tech
Livingston Enterprise 1916 (autumn) "Invests Hundreds of Thousands Will Reap Millions in Reward.”
Lovering, Thomas F., 1929, "The New World or Cooke City Mining District, Park County, Montana", U. S. Geological Survey, Bull. 811-A, pp. 1-87.
Reed, 1950, Mines and Mineral Deposits (Except Fuels), Park County, Montana. U.S. Bureau of Mines Information Circular no. 7546. GPO, Washington.
pubs.usgs.gov/pp/1717/downloads/pdf/p1717M.pdf
Elliott, J.E., 1979, Geologic map of the southwest part of
the Cooke City quadrangle, Montana and Wyoming: U.S. Geological Survey Miscellaneous Investigations Series Map I-1084, scale 1:24,000
Ruins of the workings around the Homestake Mine hang on the side of Henderson Mountain in the New World Mining District outside Cooke Montana. This panorama shows the view from the mine looking to the north, east and southeast. From Right to left the features visible are the valley of Fisher Creek, The Beartooth Plateau, Sheep Mountain; Wolf Peak (notched peak visible in gap between lower mountains); Scotch Bonnet Mountain; Lulu Pass; Fisher Mountain.
Ruins of the workings around the Homestake Mine hang on the side of Henderson Mountain in the New World Mining District outside Cooke Montana. From this view looking north from right to left over what was the upper terminal of the ore tram, Fisher Mountain, Lulu Pass, and Scotch Bonnet are visible, Geologically, the New World mining district is in the Cooke City structural zone. About half of the area is underlain by PreCambrian schist, gneiss, and granite. The Beartooth Mountains and Wolf Peak are composed of these igneous and metamorphic rocks. To the southwest the PreCambrian rocks are overlain by Paleozoic sediments, including the Flathead quartzite, Gros Ventre shale and limestone, Gallatin limestone, Big Horn dolomite, Jefferson limestone, Three Fork shale, and Madison limestone. Eocene Absaroka Volcanics lie unconformably on Paleozoic rocks. The Fisher Mountain, The Homestake mine and nearby mines are in the Tertiary stocks that have intruded into the overlying rocks. The intrusives are stocks of diorite, monzonite, syenite, and gabbro; and dikes and sills, of various compositions. Scotch Bonnet Mountain has mineralized zones on the edge of a diorite intrusive.
The mineralization often occurs at the contacts between the different rock types and in the intrusives. These zones were sometimes rich with gold, silver, copper, lead and zinc. High sulfide (pyrite-chalcopyrite) zones are commonly associated with areas of gold, silver and copper bearing ore.
In 1949, the Homestake group of mines, owned by Parkmont Mining Co., included 18 patented and two unpatented claims. This mine can be traced back to 1885 when Sam Mathers filed a claim on what became the Homestake mine. Two years later, Mathers shipped 30 tons of ore from the mine to a smelter in Salt Lake City. The ore netted him $3,000 and encouraged him to continue work on the mine's three adits, numerous crosscuts and minor drifts. A shop and shed were constructed near the intermediate level adit. The gold and silver mine was one of 279 mining claims in the New World District and, along with the Alice E. and Daisy mines also on Henderson Mountain, was one of the most productive. A small tent camp, located below the mine may have been associated with the workings in the late 19th century. By 1894, mining at the Homestake had ceased in the wake of the Silver Purchase Act and the resulting national depression. By 1916, however, the Western Smelting and Power Company had purchased the claim, along with the Gold Dust claim, and planned extensive development of both mines. Located 700 feet below the Homestake, Gold Dust mining engineers and geologists expected to tap into the rich gold-copper veins exposed in the Homestake mine. In anticipation of the strike and the completion of the smelter in 1923, the company began construction of an aerial tram that connected the Homestake mine with the Gold Dust mine and the smelter, almost two miles away. At the time of connection with the aerial tram, the Homestake mine consisted of three adits and 700 feet of workings. Despite the predictions of the Western Smelting and Power Company planners, the ore body present in the Homestake mine was never struck by the Gold Dust miners. Both mines ceased operations by 1930. In 1948, the Parkmont Mining Company of Cooke City began a small open-cut mine on the Homestake claim and was recovering 70 tons of $11 ore daily by 1949. The open-cut was worked by a Koehring diesel shovel and a Sullivan wagon drill. By 1950, the underground workings were inaccessible
References:
deq.mt.gov/Land/abandonedmines/linkdocs/154tech
Livingston Enterprise 1916 (autumn) "Invests Hundreds of Thousands Will Reap Millions in Reward.”
Lovering, Thomas F., 1929, "The New World or Cooke City Mining District, Park County, Montana", U. S. Geological Survey, Bull. 811-A, pp. 1-87.
Reed, 1950, Mines and Mineral Deposits (Except Fuels), Park County, Montana. U.S. Bureau of Mines Information Circular no. 7546. GPO, Washington.
pubs.usgs.gov/pp/1717/downloads/pdf/p1717M.pdf
Elliott, J.E., 1979, Geologic map of the southwest part of
the Cooke City quadrangle, Montana and Wyoming: U.S. Geological Survey Miscellaneous Investigations Series Map I-1084, scale 1:24,000
Tight folds in migmatitic gneiss -- the field of view is about one metre wide. In this complexly deformed rock, the limbs of the whitish folds have been severed by shearing along the metamorphic layering. (For a lengthy explanation of this rock type, see my previous "Structures in metamorphic rock - #2" photo, in my "Geology in building stone" album.)
This smooth clean polished surface is from some ornamental building stone in downtown Calgary.
C. J.R. Devaney
In Wind River Canyon between Thermopolis (Hot Spring County) and Shoshone (Fremont County) the Wind River cuts through the Owl Creek Uplift, a faulted anticline formed by the Wind River Thrust Fault during the Laramide compressional mountain building events. The core of the anticline is cored by Precambrian (Archean) crystalline rocks shown in the lower half of the photo. Also visible in the photo are channels of Cambrian Flathead Sandstone that lie unconformably on the Precambrian rocks. In the 1990s I was with a field trip of teachers from middle schools and high schools in Louisiana on a field trip across western Wyoming to look at geology. Dr. Frank Hall, then at the University of New Orleans, crawled out of the van at this location, looked up and identified the lenses. He had never been to this location before. I was impressed because I had driven by it for years, since I was a kid, before I noticed it. Geology is a science that builds on the works and understanding of others. I am grateful for the great geologist with whom have had the privilege of doing field work or taking field trips. Also thankful for all those who share their knowledge and insights through books, articles, papers and talks.
The Flathead Sandstone marks the first record of Paleozoic sedimentation in Wyoming. These sediments were deposited 520-505 million years ago in the Middle Cambrian as a sea flooded on to the exposed continental rocks. In Wind River Canyon the basal units are made up of conglomerates and arkosic sandstone which were deposited by braided streams. They are overlain by crossbedded deltaic sandstone and minor shaley beds. The Flathead sediments were sourced from the Precambrian crystalline rocks.
Most of the Precambrian rocks started out as sediments and basalts deposited in a trough on the margins of the Wyoming Craton during the Archean, about 2.9 bya. Metamorphism of these rocks occurred around 2.7 bya which resulted in black schists and amphibolites that was later intruded by white to pinkish gray quartz monzonite (Granite). The Precambrian rocks shown in the photo are mostly the quartz monozonite. These rocks represent a time when Wyoming was a separate microcontinent (the Wyoming Craton) which existed 500 million years before the North American Continent formed.
The contact between the Flathead sandstone and the metamorphic igneous complex is an uncomformity recognizable worldwide and sometimes called the Great Unconformity. In the rock record unconformities that place sedimentary rock over older metamorphic-igneous complexes usually indicate a long period of erosion occurred prior to deposition of the sediments. In this particularly case, the overlying Cambrian Flathead Sandstone is 520- 505 million years old while the underlying Precambrian Granite and Gneiss dates from around 2.7 billion years. That represents a gap in the rock record in this part of Wyoming of over 2 billion years.
References:
Condie, K C., 1967, Petrologic reconnaissance of the Precambrian rocks in the Wind River Canyon, central Owl Creek Mountains, Wyoming: University ofWyoming Contributions to Geology, v. 6, p. 123-129.
Molzer, P. & Erslev, Eric. (1995). Oblique convergence during northeast-southwest Laramide compression along the east-west Owl Creek and Casper Mountain Arches, central Wyoming. Aapg Bulletin - AAPG BULL. 79. 1377-1394.
Mueller, P. A, Peterman, Z. E., and Granath, J. W., 1985, AbimodalArchean volcanic series, Owl Creek Mountains, Wyoming: Journal ofGeology, v. 93, p. 701-712.
Beyond the ancient metamorphic rock of Mineral Peak rise the southernmost glaciated mountains of the Sierra Nevada. The crest of this valley is, per the NPS, a remnant "of volcanic islands that were added to North America before the Sierra Nevada uplift," i.e. the granite mountains seen here and in most of the range.
Blueschist is a peculiar metamorphic rock, generally limited to subduction zones such as Calif's coastal margin, known to geologists (and others) as an Active Margin. This was a big change for me, as I went to school in Houston and North Carolina, both geologically passive margins.
Anyway: this photo is from a prominent Blueschist 'knocker' on the coastal trail from Lone Palm road to New San SImeon, about a half-mile north of that trailhead. An excellent place to examine this uncommon rock. If you look closely, you will also find a Bedrock Mortar from earlier days.
It looks like a mix of a dark basaltic and a light granitic rock that's been through the wringer. Many thanks to Mike Beauregard for the explanation: it's called a migmatite (see below).
Part of a desk light in my office…
(Pixar lamp style…) :))
Tools: Aperture, Color Efex Pro 4. (No Silver Efex Pro 2 or b/w conversion was used this time!)
Found this scene at Scott's Run Nature Preserve. Loved all the contrasts the metamorphic rocks provided with the smaller sandstone in this sort of abstract shot.
Visit my website www.jcernstphoto.com
Serpentine rock (serpentinite) is apple-green to black and is often mottled with light and dark colored areas. It has a shiny or wax-like appearance and slightly soapy feel. Serpentine is usually fine-grained and compact but may be granular, platy or fibrous. It’s found in central and northern California in the Coast Ranges.
This serpentine outcropping was photographed at Edgewood Park and Natural Preserve in Redwood City, California. The infamous San Andreas Fault runs just west of the preserve at the base of the Santa Cruz Mountains. The colliding North American and Pacific Plates created this jumble of rocks known as the Franciscan complex, which dominates Edgewood.
Serpentine is metamorphic and/or magnesium-rich igneous rock, most commonly peridotite, from the earth’s mantle. (The mantle is a thick layer of rock just below the earth’s crust.) Peridotite underlying oceanic crustal rocks was metamorphosed to serpentine in subduction zones that existed at various times in California’s past. (A subduction zone is where ocean crust rocks run into and slide underneath the edge of a continent.) Because serpentine has a much lower density than peridotite, it rose toward the surface along major regional thrust faults associated with the subduction zones.