View allAll Photos Tagged quartzite
Cross-bedded pebbly quartzite in the Precambrian of Wisconsin, USA.
The Baraboo Ranges of southern Wisconsin are dominated by a hard, erosion-resistant Precambrian metamorphic unit called the Baraboo Quartzite. These rocks were originally marine sandstones and have been subjected to metamorphism and structural folding. Original sedimentary structures are preserved, such as cross-bedding and ripple marks. Baraboo Quartzites vary in color from pinkish to dark reddish to grayish. During metamorphism, quartz overgrowths formed over the original quartz sand grains. Long-term, modern weathering can result in original sand grains being released.
This unit has economic significance - it has been quarried historically and in modern times. The quartzite is broken down into gravel-sized pieces for use as railroad ballast and erosion-control rip-rap.
The tilted layers seen here are cross-bedding, formed in a one-directional current by wind or water - in this case, water.
Stratigraphy: Baraboo Quartzite, upper Paleoproterozoic, ~1.7 Ga
Locality: Tumbled Rocks Trail, northwestern margin of Devil's Lake, Devil's Lake State Park, northern part of the South Range of the Baraboo Ranges, southeast of the town of Baraboo, eastern Sauk County, southern Wisconsin, USA (43° 25' 34.34" North latitude, 89° 44' 06.56" West longitude)
Quartzite with red jasper pebbles in the Precambrian of Ontario, Canada.
Southeastern Canada's ~2.3 billion year old Lorrain Formation includes some beautiful rocks that rockhounds have nicknamed "puddingstone". This refers to whitish-gray quartzites having common pebbles of red jasper.
The Lorrain Formation is somewhat heterolithic. Published studies mention that the unit has arkoses, subarkoses, quartzites, and jasper-pebble conglomerates. The latter two lithologies are present at the glacially-eroded outcrop seen here. The quartzites were originally sandstones. They have been well cemented and somewhat metamorphosed into very hard rocks. The jasper-pebble conglomerates, or "puddingstones", include clasts of white quartz and reddish jaspilites.
Jaspilite is a type of BIF (banded iron formation). BIFs only formed on Earth during the Precambrian - most are Paleoproterozoic in age. They are the # 1 source of iron ore for the world's steel industry. Numerous specific types of BIFs are known. Jaspilite consists of alternating laters of red and silvery-gray, iron-rich minerals. The red layers are hematite or jasper (= hematitic chert). The silver-gray layers are usually rich in magnetite and/or specular hematite. Jaspilite BIFs outcrop in many areas around Lake Superior, for example in Michigan's Upper Peninsula, Minnesota, and Ontario.
During the Paleoproterozoic, BIFs were subaerially exposed as paleo-outcrops and eroded, producing BIF sediments, including many red jasper pebbles. These mixed with quartz-rich sediments.
Regional studies indicate that the Lorrain Formation was deposited in ancient shallow ocean, lake, delta, and shoreline environments.
Stratigraphy: Lorrain Formation, upper Cobalt Group, Huronian Supergroup, Paleoproterozoic, ~2.3 Ga
Locality: Ottertail Lake Northeast Roadcut - glacial knob on the eastern side of Rt. 638, northeast of Ottertail Lake & southeast of Rock Lake, north-northeast of the town of Bruce Mines, southern Ontario, southeastern Canada (46° 23' 30.59" North latitude, 83° 43’ 10.94" West longitude)
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Some info. synthesized from:
Hadley (1970) - Paleocurrents and origin of Huronian Lorrain Formation, Ontario and Quebec. American Association of Petroleum Geologists Bulletin 54: 850.
Pipestone County Courthouse, 416 South Hiawatha, Pipestone, Minnesota. This 1902 courthouse is a Beaux Arts style building featuring a Renaissance dome on a clock tower with heavily rusticated masonry and Sioux quartzite. A bronze Lady Justice stands on the dome. The interior is finished with elaborate oak woodwork. A multicolored mantle in the foyer was constructed from pipestone in a Native American motif. The building was constructed by C.H. Peltier of Faribault for $45,175. The architect was George Pass of Mankato, Minnesota. The building was placed on the National Register of Historic Places in 1980.
Horizontally-bedded quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.
The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
The Sioux Quartzite has been quarried in southeastern South Dakota and southwestern Minnesota. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Horizontally-bedded quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.
The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
The Sioux Quartzite has been quarried in southeastern South Dakota and southwestern Minnesota. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Quartzite with red jasper pebbles in the Precambrian of Ontario, Canada.
Southeastern Canada's ~2.3 billion year old Lorrain Formation includes some beautiful rocks that rockhounds have nicknamed "puddingstone". This refers to whitish-gray quartzites having common pebbles of red jasper.
The Lorrain Formation is somewhat heterolithic. Published studies mention that the unit has arkoses, subarkoses, quartzites, and jasper-pebble conglomerates. The latter two lithologies are present at the glacially-eroded outcrop seen here. The quartzites were originally sandstones. They have been well cemented and somewhat metamorphosed into very hard rocks. The jasper-pebble conglomerates, or "puddingstones", include clasts of white quartz and reddish jaspilites.
Jaspilite is a type of BIF (banded iron formation). BIFs only formed on Earth during the Precambrian - most are Paleoproterozoic in age. They are the # 1 source of iron ore for the world's steel industry. Numerous specific types of BIFs are known. Jaspilite consists of alternating laters of red and silvery-gray, iron-rich minerals. The red layers are hematite or jasper (= hematitic chert). The silver-gray layers are usually rich in magnetite and/or specular hematite. Jaspilite BIFs outcrop in many areas around Lake Superior, for example in Michigan's Upper Peninsula, Minnesota, and Ontario.
During the Paleoproterozoic, BIFs were subaerially exposed as paleo-outcrops and eroded, producing BIF sediments, including many red jasper pebbles. These mixed with quartz-rich sediments.
Regional studies indicate that the Lorrain Formation was deposited in ancient shallow ocean, lake, delta, and shoreline environments.
Stratigraphy: Lorrain Formation, upper Cobalt Group, Huronian Supergroup, Paleoproterozoic, ~2.3 Ga
Locality: Ottertail Lake Northeast Roadcut - glacial knob on the eastern side of Rt. 638, northeast of Ottertail Lake & southeast of Rock Lake, north-northeast of the town of Bruce Mines, southern Ontario, southeastern Canada (46° 23' 30.59" North latitude, 83° 43’ 10.94" West longitude)
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Some info. synthesized from:
Hadley (1970) - Paleocurrents and origin of Huronian Lorrain Formation, Ontario and Quebec. American Association of Petroleum Geologists Bulletin 54: 850.
Quartzite statue of Ankhrekhu
From Egypt
12th Dynasty, 1985-1795 BC
A Middle Kingdom official wearing a cloak
Egyptian sculpture is often thought to consist only of massive and regal statues of the pharaohs of Egypt. However, there exist also more intimate images, so-called 'private' sculptures, made to be placed in the tombs of ordinary people.
This statue shows the official Ankhrekhu seated, and wrapped in a cloak, a common feature of the private statuary of the Middle Kingdom (about 2040-1750 BC). He has a slightly serious expression, and larger than average ears, common in that period in both private and royal statues. He wears a wig that was conventional in the Middle Kingdom (about 2040-1750 BC). The folds of the drapery over the figure are carefully carved, and the fringed edge to the material of the cloak is indicated.
Ankhrekhu was an official with important courtly titles that indicate his rank. One of his main functions seems to have been that of overseer of priests, but it is not known in which temple, or of which god.
Height: 71.000 cm Width: 45.800 cm
Bequeathed by Lady Coote.
from: www.britishmuseum.org
The Zabriskie Quartzite is a hard, cliff-forming unit originally deposited as marine sands along a continental margin during the Lower Cambrian period about 560 million years. It is well exposed here at Aguereberry Point. Death Valley National Park. Inyo Co., Calif.
Fluvially-polished quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, South Dakota. The quartzites here have nicely water-worn, sculpted surfaces. These rocks are part of the Sioux Quartzite, which consists of 1.65 to 1.70 billion year old metamorphosed sandstones. Despite the metamorphism, original sedimentary features such as horizontal stratification, cross-bedding, and ripple marks are still preserved.
The Sioux Quartzite is an erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a northeast-to-southwest trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
Quarries of Sioux Quartzite occur in southeastern South Dakota and southwestern Minnesota. The rocks are used as building stone, road gravel, sidewalk and paving gravel, and erosion control material.
The shiny areas on this Sioux Quartzite surface are fluvial polish. During times of energetic flow by the nearby Big Sioux River, abrasion from sediments have eroded, scoured, smoothed, and polished the rocks. Naturally polished rocks can also form by glacial action (glacial polish), faulting (structural polish or fault polish), and wind action, which results in ventifacts.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Quartzite with fluvial abrasion polish in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.
The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
The Sioux Quartzite has been quarried in southeastern South Dakota and southwestern Minnesota. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Red palster cast of a quartzite head of a princess. The original, from House U37.1 in the North Suburb of Akhetaten, is in Cairo Museum.
Petrie Museum, London. UC 24317
The Tasmanian endemic Xerochrysum collierianum (quartzite everlasting) flowering on rock outcrops on Mt Claude. This species was described in 2004 and is restricted to the west of the state where it occurs in rocky outcroppings of quartzite.
Quartzite from the Precambrian of the Transcontinental Arch, USA. (4.5 centimeters across at its widest)
Metamorphic rocks result from intense alteration of any previously existing rocks by heat and/or pressure and/or chemical change. This can happen as a result of regional metamorphism (large-scale tectonic events, such as continental collision or subduction), burial metamorphism (super-deep burial), contact metamorphism (by the heat & chemicals from nearby magma or lava), hydrothermal metamorphism (by superheated groundwater), shear metamorphism (in or near a fault zone), or shock metamorphism (by an impact event). Other categories include thermal metamorphism, kinetic metamorphism, and nuclear metamorphism. Many metamorphic rocks have a foliated texture, but some are crystalline or glassy.
Quartzite is a common, crystalline-textured, intermediate- to high-grade metamorphic rock. It forms by metamorphism of quartzose sandstones or siltstones. Quartzite can be entirely composed of interlocking quartz crystals, or the original sand grains may still be visible. This rock is hard (H = 7), will not bubble in acid (unlike marble), and can be almost any color.
The term “quartzite” has been used in geology to refer to crystalline, quartzose metamorphic rocks and to hard, well-cemented quartzose sandstones that have not been subjected to metamorphism. It is difficult to not call hard, well-cemented sandstones “quartzite” - for example, the Clinch Quartzite in the Appalachian Mountains and the Eureka Quartzite of the Great Basin in western USA, but the Clinch and Eureka aren’t metamorphic rocks. The term "metaquartzite" has been used by some geologists to refer to crystalline-textured, quartzose rocks that have been metamorphosed. This implies that “quartzite” be restricted to well-cemented, non-metamorphosed sandstones. I don’t often see the term metaquartzite in the geologic literature.
The quartzite sample seen here is from the Precambrian-aged Sioux Quartzite, which outcrops in southeastern South Dakota and southwestern Minnesota. Despite being regionally metamorphed, the unit’s original sedimentary features, such as horizontal stratification, cross-bedding, and ripple marks, are still apparent in some outcrops.
The Sioux Quartzite is a erosion-resistant unit in a long-lived paleotopographic high called the Sioux tectonic core. This high has existed since Precambrian times and is part of a northeast-southwest trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65 to 1.70 Ga
Locality: undetermined quarry; collected from railroad ballast at Missouri Valley, Iowa, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
This, sculpture, made of quartzite, was found in the main courtyard of the House of "Thutmose the Sculptor" in Amarna, Egypt. That was the same house where the famous bust of Nefertiti and many other sculptures now in the Neues Museum were found. This one was found face-up and surrounded by the remains of a wig. It was also made to be mounted onto a sculpted body.
Ring made from silver, found iron stamped with "ALPHA +" and white quartzite stone.
Taken with Panasonic 20mm f1.7 lens on Panasonic GH2.
From Egypt
18th Dynasty, around 1350 BC
'He who cuts off the face of him who cuts off your face'
This inscription on the statue appears to identify it with Hapy the son of Horus. Yet this baboon still reminds of the Cynocephalus ape of Thoth.
Ancient Egyptians might identify the baboon with at least three main deities. The first was the sun-god, as baboons screech at sunrise. Religious papyri often depict baboons adoring the rising sun. The second deity, who this sculpture is normally thought to represent, is Thoth, the ibis-headed god of Hermopolis. Amenhotep III (1390-1352 BC), whose names are incised on the pedestal of this small figure, in fact set up four colossal baboon statues at Hermopolis, the centre of Thoth's cult.
However, the baboon is also associated with Hapy, one of the four sons of Horus. The inscription on this statue suggests that it might be Hapy who is represented here, as it bears the epithet 'He who cuts off the face of him who cuts off your face', which is usually identified with the guardian Hapy.
The figure is carved from the brown quartzite of Lower Egypt so favoured by Amenhotep III. It has been suggested that the statue may have come from Amenhotep's tomb, but divine statues in royal burials are more likely to have been made of wood. It seems more likely that this is one of the huge number of statues of deities made for Amenhotep's mortuary temple on the west bank of the Nile.
A.P. Kozloff and B.M. Bryan, Egypts dazzling sun: Amenhotep (Cleveland Museum of Art, 1992)
S. Quirke and A.J. Spencer, The British Museum book of anc (London, The British Museum Press, 1992)
British Museum
Room 4: Egyptian sculpture
www.britishmuseum.org/explore/highlights/highlight_object...
Cross-bedded pebbly quartzite in the Precambrian of Wisconsin, USA.
The Baraboo Ranges of southern Wisconsin are dominated by a hard, erosion-resistant Precambrian metamorphic unit called the Baraboo Quartzite. These rocks were originally marine sandstones and have been subjected to metamorphism and structural folding. Original sedimentary structures are preserved, such as cross-bedding and ripple marks. Baraboo Quartzites vary in color from pinkish to dark reddish to grayish. During metamorphism, quartz overgrowths formed over the original quartz sand grains. Long-term, modern weathering can result in original sand grains being released.
This unit has economic significance - it has been quarried historically and in modern times. The quartzite is broken down into gravel-sized pieces for use as railroad ballast and erosion-control rip-rap.
The tilted layers shown above are cross-bedding, formed in a one-directional current by wind or water (in this case, water).
Stratigraphy: Baraboo Quartzite, upper Paleoproterozoic, ~1.7 Ga
Locality: Tumbled Rocks Trail, northwestern margin of Devil's Lake, Devil's Lake State Park, northern part of the South Range of the Baraboo Ranges, southeast of the town of Baraboo, eastern Sauk County, southern Wisconsin, USA (43° 25' 34.34" North, 89° 44' 06.56" West)
Looking along the Devil's Chair, which is a rocky Quartzite Tor which has been subjected to intense freezing and thawing from the ice age. I decided to clamber up into the rocks for a better look and a wonder around these amazing rocks. It's been a long time since I did any climbing, so I decided not to carry on any further and just get this precipitous shot. This was my first visit to these Shropshire Hills and I will be certainly visiting again.
Doug scrambling on steep quartzite on Uto Peak in Rogers Pass. The route actually goes more left to right on a ledge than straight up to me.
Quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, South Dakota. The quartzites here have nicely water-worn, sculpted surfaces. These rocks are part of the Sioux Quartzite, which consists of 1.65 to 1.70 billion year old metamorphosed sandstones. Despite the metamorphism, original sedimentary features such as horizontal stratification, cross-bedding, and ripple marks are still preserved.
The Sioux Quartzite is an erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a northeast-to-southwest trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
Quarries of Sioux Quartzite occur in southeastern South Dakota and southwestern Minnesota. The rocks are used as building stone, road gravel, sidewalk and paving gravel, and erosion control material.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Rising to 2510 feet (765 meters) near the town of Westport in County Mayo, the quartzite peak of Croach Patrick was a pagan sacred place long before the arrival of Christianity. For the Celtic peoples of Ireland it was the dwelling place of the deity Crom Dubh and the principal site of the harvest festival of Lughnasa, traditionally held around August 1 (until the mid-nineteenth century only women were allowed on the summit during this pilgrimage and childless women would sleep on the summit during Lughnasa eve in the hope of encouraging fertility). According to popular Christian stories, St. Patrick visited the sacred mountain during the festival time in AD 441 and spent forty days and forty nights banishing dragons, snakes, and demonic forces from the site. Were there dragons and demonic forces actually living atop this mountain, or does the legend have a metaphorical rather than a literal meaning? To shed light on this matter it is important to know something of the person known as St. Patrick, the patron saint of Ireland.
Patrick is not actually Irish. He was born in Britain around AD 385. Captured in his youth by Irish pirates raiding the Scottish coast, he was sold into slavery in Ireland. Later escaping to Europe, Patrick spent some years studying at the monastery of St. Martin of Tours in France, where he was ordained as a priest. Deeply affected by the Christian missionary zeal so prevalent in the early fifth century, he decided to return to Ireland to undertake the conversion of the Celtic pagans and their Druid priests. Arriving in Ireland in AD 432, Patrick spent nearly thirty years traveling about the countryside, bringing Christianity to the local people and establishing churches and monastic foundations upon many Druidic sacred sites, which had themselves been established upon far more ancient megalithic sites of the Grooved Ware people. Patrick later retired to Glastonbury, England, where he died at the age of 111.
It was common for early Christians to view pagan religious practices as devil worship; thus the legend of Patrick slaying dragons and demonic forces on the sacred mountain is actually a metaphor for his subjugation and conversion of the pagan priests. In support of the pre-Christian sanctity of the mountain it is important to note that Neolithic foundations have been found on the summit and, on a natural rock outcrop (known as ‘St. Patrick’s Chair) along the pilgrimage route to the summit, Neolithic art has been discovered. By the seventh century the holy mountain had become one of the two most important Christian pilgrimage sites in all Ireland (the other being Station Island, also called St. Patrick's Purgatory, in Lough Derg near the town of Sligo). Prior to AD 1113 the pilgrims came to the mountain during Lent, but following a wild storm in which thirty pilgrims died upon the peak, the pilgrimage period was changed to summer, with the most popular days being the last Friday and Sunday of July.
Currently it is estimated that nearly one million pilgrims climb to the summit each year, as many as forty thousand on the last Sunday in July. In the Irish Christian tradition the ascent is undertaken as an act of penance for wrongdoing, and many of the pilgrims climb barefooted or even on their knees. The ancient worship at Mt. Croach Patrick, however, had nothing to do with matters of penance and supposed wrongdoing. The holy mountain was a sanctuary for the giving of thanks and the celebration of life's abundance. Similar to what occurred at many other prehistoric sacred places across Europe, at Croach Patrick Christianity has warped, stifled and corrupted the natural human tendency to venerate life and the Earth's beauty, while imposing ideas of fear, guilt, and control. This great sacred mountain certainly does not wallow in such limiting, life-denying concepts nor does it require or support humans in doing so. Mt. Croach Patrick was - and still is - a place to experience and give thanks for the exquisite beauty of life.
Horizontally-bedded quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.
The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
The Sioux Quartzite has been quarried in southeastern South Dakota and southwestern Minnesota. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Quartzite in the Precambrian of South Dakota, USA.
Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.
The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).
The Sioux Quartzite has been quarried in southeastern South Dakota and southwestern Minnesota. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.
Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga
Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA
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Reference cited:
Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.
Overturned cross-bedding in quartzite in the Precambrian of Wisconsin, USA.
The Baraboo Ranges of southern Wisconsin are dominated by a hard, erosion-resistant Precambrian metamorphic unit called the Baraboo Quartzite. These rocks were originally marine sandstones and have been subjected to metamorphism and structural folding. Original sedimentary structures are preserved, such as cross-bedding and ripple marks. Baraboo Quartzites vary in color from pinkish to dark reddish to grayish. During metamorphism, quartz overgrowths formed over the original quartz sand grains. Long-term, modern weathering can result in original sand grains being released.
This unit has economic significance - it has been quarried historically and in modern times. The quartzite is broken down into gravel-sized pieces for use as railroad ballast and erosion-control rip-rap.
The tilted layers shown above are cross-bedding, formed in a one-directional current by wind or water (in this case, water). Notice that the upper portions of the cross-bedded interval are bent to the right. Those cross-beds have been overturned by shearing by the same one-directional current that formed the overall cross-bed set. Overturned cross-beds are rare sedimentary structures, but they are thought to be commonly formed. Their scarcity appears to be the result of post-deposition erosion usually removing the upper portions of overturned cross-bedded sediment packages.
Stratigraphy: Baraboo Quartzite, upper Paleoproterozoic, ~1.7 Ga
Locality: Tumbled Rocks Trail, northwestern margin of Devil's Lake, Devil's Lake State Park, northern part of the South Range of the Baraboo Ranges, southeast of the town of Baraboo, eastern Sauk County, southern Wisconsin, USA (43° 25' 34.34" North, 89° 44' 06.56" West)
From Egypt
18th Dynasty, around 1350 BC
'He who cuts off the face of him who cuts off your face'
This inscription on the statue appears to identify it with Hapy the son of Horus. Yet this baboon still reminds of the Cynocephalus ape of Thoth.
Ancient Egyptians might identify the baboon with at least three main deities. The first was the sun-god, as baboons screech at sunrise. Religious papyri often depict baboons adoring the rising sun. The second deity, who this sculpture is normally thought to represent, is Thoth, the ibis-headed god of Hermopolis. Amenhotep III (1390-1352 BC), whose names are incised on the pedestal of this small figure, in fact set up four colossal baboon statues at Hermopolis, the centre of Thoth's cult.
However, the baboon is also associated with Hapy, one of the four sons of Horus. The inscription on this statue suggests that it might be Hapy who is represented here, as it bears the epithet 'He who cuts off the face of him who cuts off your face', which is usually identified with the guardian Hapy.
The figure is carved from the brown quartzite of Lower Egypt so favoured by Amenhotep III. It has been suggested that the statue may have come from Amenhotep's tomb, but divine statues in royal burials are more likely to have been made of wood. It seems more likely that this is one of the huge number of statues of deities made for Amenhotep's mortuary temple on the west bank of the Nile.
A.P. Kozloff and B.M. Bryan, Egypts dazzling sun: Amenhotep (Cleveland Museum of Art, 1992)
S. Quirke and A.J. Spencer, The British Museum book of anc (London, The British Museum Press, 1992)
British Museum
Room 4: Egyptian sculpture
www.britishmuseum.org/explore/highlights/highlight_object...
Asymmetrical ripple marks in quartzite in the Precambrian of Wisconsin, USA.
The Baraboo Ranges of southern Wisconsin are dominated by a hard, erosion-resistant Precambrian metamorphic unit called the Baraboo Quartzite. These rocks were originally marine sandstones and have been subjected to metamorphism and structural folding. Original sedimentary structures are preserved, such as cross-bedding and ripple marks. Baraboo Quartzites vary in color from pinkish to dark reddish to grayish. During metamorphism, quartz overgrowths formed over the original quartz sand grains. Long-term, modern weathering can result in original sand grains being released.
This unit has economic significance - it has been quarried historically and in modern times. The quartzite is broken down into gravel-sized pieces for use as railroad ballast and erosion-control rip-rap.
The ridges on the rock shown above are asymmetrical ripples. Asymmetrical ripple marks have a long side and a short side, when viewed in cross-section. They form in a one-directional current by wind or water (in this case, water). The current direction was toward the short side of each ripple.
Stratigraphy: Baraboo Quartzite, upper Paleoproterozoic, ~1.7 Ga
Locality: loose block along the southern shore of Devil's Lake, Devil's Lake State Park, northern part of the South Range of the Baraboo Ranges, southeast of the town of Baraboo, eastern Sauk County, southern Wisconsin, USA