Prehistoric flint pit (Flint Ridge, Licking County, Ohio, USA) 46 : 無料・フリー素材/写真
Prehistoric flint pit (Flint Ridge, Licking County, Ohio, USA) 46 / James St. John
ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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説明 | Flint is the state gemstone of Ohio. "Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin.Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules).The most famous flint deposit in Ohio is Flint Ridge, in Licking County. At this locality, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.Two graduate student projects during the 2000s, conducted at two different universities, had very different conclusions & interpretations about the origin of the Vanport Flint. A 2003 study concluded that chert at Flint Ridge is biogenic in origin. A 2006 study concluded that the chert is chemical in origin.Modern flint knappers value the Vanport Flint for being multicolored and high-quality (= very few impurities). With artificial heating, the flint is more easily knapped into arrowheads, spear points, and other objects. Prehistoric American Indians quarried the Vanport Flint at many specific sites on Flint Ridge. Old flint pits can be seen in Flint Ridge State Park. Many authentic artifacts found in Ohio (arrowheads & spearpoints - "projectile points") and elsewhere are composed of Vanport Flint.---------------------------------------Info. from park signage:FLINT RIDGEFor more than 10,000 years, Flint Ridge was one of the most important flint quarries in eastern North America. The flint formed at the bottom of a shallow ocean 300 million years ago. The softer rocks surrounding the flint have washed away, leaving the hard flint exposed near the surface. Prehistoric people came here to quarry the flint, which they crafted into a variety of stone tools. Hundreds of quarry pits and workshops are scattered for miles along this ridge. The beautiful rainbow-colored flint was especially prized by the Hopewell culture that built the nearby Newark Earthworks. Artifacts crafted from Flint Ridge flint may be found throughout eastern North America. In more recent times, local industries quarried the flint for use as grindstones.-------FLINT RIDGEFlint Ridge is a chain of long, narrow hills extending from a few miles east of Newark almost to Zanesville, a distance of more than twenty miles. The surface of these hills is underlaid with an irregular layer of flint, which may be only a few inches or several feet in thickness and varies greatly in color and texture. In many places along this ridge, the soil has been eroded, revealing the underlying flint. You are standing at one of these outcroppings.Flint is formed by a geologic process whereby the softer limestones and shales are replaced with much harder silica. Due to its high quartz content, flint polishes beautifully and exceptional pieces of jewelry can be made from it. The 106th General Assembly designated flint as Ohio's offical gem stone in 1965 because of its occurrence in several parts of Ohio, particularly Flint Ridge, and because of its importance as a semi-precious gem stone.Flint is both hard and brittle and thus can be broken into pieces that have razor sharp edges. For this reason, Indians as long as 9000 years ago traveled to this ridge to secure the rock for making projectile points, knives, and scrapers. The area is now covered with hundreds of shallow pits from which flint has been quarries through the ages; several are visible along the trails. The prehistoric Indians broke off chunks of flint with stone mauls and pried them out of the pits with wooden poles. They broke the chunks into usable pieces with hammerstones and then proceeded to chip the flint for various purposes.-------FLINT RIDGEThe history of American Indians in Licking County goes back 14,000 years, and countless generations of native people spent full and varied lives in this area. Probably the best known are those whom archaeologists identify as the Hopewell, who left their imprint in the form of monumental earthworks, including the Newark Earthworks located just 11 miles from here.Flint - specifically, Vanport or Flint Ridge flint - contributed significantly to this rich human history. As you stand here today at Flint Ridge Ancient Quarries & Nature Preserve, you're standing a few feet above a layer of flint 10-12 feet thick that stretches for 8 miles from east to west and for 3 miles from north to south. This flint deposit is so large that it actually shapes the landscape of Flint Ridge. First, it influences how and where trees grown and fall. Second, 14,000 years' worth of quarrying by the people who originally lived here changed the area's ecology.-------THIS QUARTER-MILE TRAIL SHARES THE STORY OF FLINT RIDGEFLINT: "OHIO'S GEMSTONES", BUT WHY?Vanport flint formed at the bottom of an ocean millions of years ago, and its unique properties made it a valuable source of material for crafting tools for ancient American Indians and early European settlers. Today, Vanport flint, with its rich and varied colors, is prized as Ohio's state gemstone.TECHNOLOGY: MINING AND CRAFTING FLINTThe quarries and workshops at Flint Ridge are the traces of Ohio's first industry. The flint was dug from the ground and shaped into many kinds of tools.THE PEOPLE OF THE RIDGEStudying flint tools found in this area - how they were made and how they were used - provides insight into the American Indian people who lived in central Ohio prior to European contact.NATURAL HISTORY: FOR EVERYTHING THERE IS A SEASONThe ancient flint quarries have becom vernal pools (temporary wetlands) that are now home to a variety of plants and animals. In addition, the presence of the flint layer just a few feet underneath the soil greatly influences the ways that trees in the area grow.-------OHIO'S GEMSTONEVANPORT FLINTThe flint deposits at Flint Ridge are found in rocks of the geologic era known as the Pennsylvanian Period (299-320 million years ago). These deposits are the largest and purest occurrence of flint in the state. Technically called "Vanport Flint", Flint Ridge flint occurs in layers from 10 to 12 feet thick at this site. Vanport flint is particularly notable for its array of colors. Flint ranges in color from white to black, but is usually light gray to milky white and often mottled with patches and streaks. Other colors, however, such as bright red, yellow, green, and blue make Vanport flint unique. It can be so colorful that it's commonly referred to as Ohio's "rainbow" flint. The unusual beauty and historical importance of Flint Ridge flint earned it the title of Ohio's official gemstone in 1965.-------WHAT IS FLINT?Flint is a sedimentary rock - it formed from sediment, material that settled millions of years ago to the bottom of the seas that covered what is now Ohio. Flint is a type of the common mineral quartz. It's one of the "microcrystalline" forms of quartz, meaning that its crystals are so small they can't be seen without magnification. The crystals are also tightly locked together, which gives flint its even consistency and hardness. These and other properties of flint make it an ideal material for creating sharp, durable tools.-------PEOPLE AT FLINT RIDGE THROUGH TIMEDuring the Middle Woodland Period (2,000 to 1,500 years ago), Ohio's American Indian culture began to quarry Flint Ridge flint on a more industrial scale. They still used the flint to make the tools needed for the tasks of daily living, but now they began to create specialty items, such as bladelet cores and teardrop-shaped knives. These were signature artifacts of the Hopewell culture (1-450 A.D.), and Hopewell people used these beautiful objects, as burial offerings, ceremonial gifts, and trade items for distribution from special places such as the Newark Earthworks.After the decline of the Hopwell culture, later residents focused on using tool materials closer to their homes, and the use of Flint Ridge flint fell sharply. When Europeans introduced their trade goods to American Indians in the 1700s, Flint Ridge was all but abandoned. For a brief period in the 1800s to the 1920s, however, European Americans quarried Flint Ridge flint to make millstones and sandpaper.-------PEOPLE AND TECHNOLOGYMINING AND CRAFTING FLINTAt Flint Ridge, ancient American Indians quarried the flint from pits they laboriously dug by hand into the bedrock. Many of these pits are still visible along the park trails. Once the flint was exposed, it was struck with hammer stones to break it into large chunks, which where then pried out of the surrounding rock with wooden poles.Favorable pieces of flint were carried off to be knapped - expertly chipped and worked into tools. When flint is struck, it breaks into chunks withe edges as sharp as glass, and a skilled flint worker, or "knapper", can shape raw flint into precisely formed tools such as spear points, knives, scrapers, and drills. Ancient flint workers sometims used fire to heat the flint, which made it easier to knap. Heating flint also made its colors more vibrant.-------PEOPLE AT FLINT RIDGE THROUGH TIMEFrom the Paleoindian Period of North American history, which began around 14,000 years ago, through the Early Woodland Period, which ended about 2,000 years ago, ancient American Indians came to Flint Rigde when they needed flint to make new tools to replace those that were worn or broken. These early Americans probably came to the quarries at the same time each year, and their gatherings were not only an opportunity to obtain the needed flint, but also to meet friends and relatives they hadn't seen for many months.-------FOR EVERYTHING THERE IS A SEASONThe extensive flint deposits at Flint Ridge and the quarrying by early residents influenced the local ecosystem, including how nonhuman inhabitants thrive here and how trees grow in the area. Mining activities at Flint Ridge ceased hundreds of years ago, but the flint pits dug by ancient Americans remained.The ancient flint quarries have become vernal pools (temporary wetlands) that are now home to a variety of plants and animals. The flint layer just a few feet beneath the soil hinders drainage, which influences the species of trees living here.At Flint Ridge, the vernal pools are critical breeding grounds for 10 species of salamander. Several native species are unusual for the area, including the four-toed salamander, which is a "Species of Concern" in Ohio. Thriving and diverse native amphibian populations, such as those found at Flint Ridge, indicate that an ecosystem is healthy.In addition to numerous animals, this seasonal forested wetland supports several kinds of trees. American beech trees prefer wet areas, and you can see a number of them neaby. Look for their smooth, gray "elephant leg" tunks and cigar-shaped buds. Other species that thrive in this ecosystem include oak, maple, hickory, sycamore, dogwood, redbud, hop hornbeam, cherry, elm, and sweetgum.The trees' lives may be shortened because the flint underneath the soil blocks downward root growth, making the trees less stable.---------------------------------------Stratigraphy: Vanport Flint, Allegheny Group, upper Middle PennsylvanianLocality: prehistoric flint pit, Flint Ridge State Park ("Flint Ridge State Memorial"; "Flint Ridge Ancient Quarries & Nature Preserve"), southeastern side of the Flint Ridge Road-Brownsville Road intersection, southeastern Licking County, east-central Ohio, USA (vicinity of 39° 59' 15.01" North latitude, 82° 15’ 44.39" West longitude) |
撮影日 | 2025-03-29 12:39:44 |
撮影者 | James St. John |
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