Essay On Turtle Stones
Turtle Stones
By Edgar A. Brown
Concretions, some of which are called turtle stones, have been geological curiosities around the world for centuries. According to Wikipedia, a concretion is a hard, compact mass of matter formed within layers of sedimentary rock such as sandstone, shale, siltstone, and limestone. Concretions form as minerals within rock beds and precipitate in cracks and cavities, or as sediment builds up in layers around a core like a pebble or a shell.
The Finger Lakes shale holds bands of calcareous concretions that are visible in the shale layers of exposed outcroppings. The steep slopes along NY Route 21 in Woodville are an example. These smooth, nearly spherical, mostly oval-shaped calcium carbonate deposits precipitated around a core of fossilized material such as plant or animal matter. Because of their smooth oval shape they are sometimes called beetle stones. …show more content…
The evidence lies in piles of sharp shards at the bottom of some of the more popular gorges and gullies. Calcareous concretions are solid and quite common. Geodes, not common here, are specific concretions of chalcedony with hollow interiors that contain a lining of inwardly projecting silica crystals.
The classic turtle stone is a distinctly round concretion called a septarian nodule and is truly a unique find. Characteristic cracks radiate from the center to the edge and are crossed by concentric cracks dividing these concretions into segments much like the carapace of a turtle. Dehydration caused the cracks which were later filled in with another crystalline cement such as calcite or silica. Often turtle stones are found with protruding snouts or facial
By Edgar A. Brown
Concretions, some of which are called turtle stones, have been geological curiosities around the world for centuries. According to Wikipedia, a concretion is a hard, compact mass of matter formed within layers of sedimentary rock such as sandstone, shale, siltstone, and limestone. Concretions form as minerals within rock beds and precipitate in cracks and cavities, or as sediment builds up in layers around a core like a pebble or a shell.
The Finger Lakes shale holds bands of calcareous concretions that are visible in the shale layers of exposed outcroppings. The steep slopes along NY Route 21 in Woodville are an example. These smooth, nearly spherical, mostly oval-shaped calcium carbonate deposits precipitated around a core of fossilized material such as plant or animal matter. Because of their smooth oval shape they are sometimes called beetle stones. …show more content…
The evidence lies in piles of sharp shards at the bottom of some of the more popular gorges and gullies. Calcareous concretions are solid and quite common. Geodes, not common here, are specific concretions of chalcedony with hollow interiors that contain a lining of inwardly projecting silica crystals.
The classic turtle stone is a distinctly round concretion called a septarian nodule and is truly a unique find. Characteristic cracks radiate from the center to the edge and are crossed by concentric cracks dividing these concretions into segments much like the carapace of a turtle. Dehydration caused the cracks which were later filled in with another crystalline cement such as calcite or silica. Often turtle stones are found with protruding snouts or facial