Dating back to the 18th century concretions have been known as geologic curiosity’s due to the various sizes, shapes and compositions. Concretions have also been thought to be dinosaur eggs, extra-terrestrial debris, human artifacts and animal and plant fossils. Due to these curiosity’s I will try and enlighten you more on these in the following by explaining the process in which they are formed and explaining some locations where they can be found in large outcrops.
“The word "concretion" is derived from the Latin "con"-- meaning "together" -- and "cresco" -- meaning "to grow."”
Concretions are hard compact accumulations of mineral matter and are found inside sedimentary rocks. Some examples of this are Sandstone and in some weathered volcanic rock. Concretions come in many different shapes and the most common of the shapes is spherical or disk shaped. Concretions are the most varied-shaped rocks of the sedimentary world. The way concretions come to be is the mineral matter concentrates around the nucleus of a host rock. The nucleus is often organic such as a tooth or leaf or shell or fossil. As the mineral matter concentrates around the nucleus it forms harder zones known as nodules.
Concretions are very odd in the sense that they very in size, shape, color and hardness. Often concretions are mistaken for bones, fossils, meteorites and other odd objects. They can be so small that it requires a magnifying glass to be visible or as large as 10 feet in diameter and weigh hundreds of pounds. Concretions can also have somewhat of regular shapes such as boxes, blocks, flat disks, pipes, cannon balls and have even been known to resemble parts of a human body such as a foot or ribs.
Concretions are most commonly composed of calcite but sometimes can be composed of iron oxide or iron hydroxide such as goethite. But also concretions can be composed of other minerals ranging from siderite, ankerite, dolomite, pyrite, baryite and gypsum.
Concretions form in many different ways. The box shape of some ironstone concretions most often depend on the way a sandstone or shale bed breaks up due to the action of weathering into regular blocks of various sizes. The way in which this separation takes place along natural planes of weakness in a rock such as a horizontal bedding surface and vertical joints. Before this process of separation, as well as during the separation ground water soaks into the rock and circulates through the planes of weakness making the rock more porous.
The shelf-edge includes carbonate-to-clastic facies transition and tectonic uplift and erosion of the carbonates followed by deposition of the clastics. The Saint Peter Sandstone is a well-sorted, almost pure quartz arenite deposited during a major mid-Ordovician low stand. Clastics spread across an exposed carbonate platform by transportation. This is shown by the well-rounded, frosted texture of the quartz grains.
The Don Valley Brickwork consists of many different layers of geological deposits, allowing us to observe and have a better understanding of how the sediments we see today are formed. The most bottom layer in the Brickworks are from the Georgian Bay Formation, and consists of grey- shale bedrocks. Fossils are often found in this layer and it is estimated that this deposit of sediments is around 445 million years old. Above the bedrocks is a thin layer of grey clay sand and gavels left behind by the Illinoian Glacier. This layer is called the York Till and occurred around 135,000 years ago. The next layer consists of a sandy deposit called the Don Formation, which is formed by the Sangamonian Interglacial Stage. Many plant and animal fossils are found in this layer due to warmer climate around 120,000 years ago. Above it lies the Scarborough Formation, which consist of clay and sand. This sediment likely occurred 115 - 106,000 years ago. The next layer above is the Poetry Road Formation, and consist of sand and gravel. This layer is likely formed during the early Wisconsin glacial substage around 106- 75,000 years ago. Higher is the Sunnybrook Drift which was formed 60 – 75,000 years ago. And on the surface, is the Halton Till, which was left behind by the final push of the Wisconsin Glacier.
...ts were labelled with the upper case letters which represented the material types and a numeric letter. The artifacts were placed in different boxes. The artifact analysis was then conducted and the characteristics such as tool type and material type of each artifact were recorded on the artifact catalog forms. The material samples of lithic tools, faunal remains, and ceramics remains were compare with existing artifacts to identify their material type. The Vernier scale was used for the measurements of each lithic tools.
Soon after the sea reached longer distance westward and the sandy tidal deposits were converted to deep water deposits. Mancos Shale is the name given to represent these deposits, which are comprised of organic material and small particulates. Another interesting fact to note is that this type of sediment consists of fossils. These remains can include prehistoric shell fish, shark teeth, and many other types of organisms. The hills seen at the foundation of the mesa in the Montezuma Valley are comprised of gray
Shown in the picture above is volcanic extrusive igneous rock known as andesite. They were imported here to Laguna Beach to help minimize erosion (Merton Hill, p. 10-11). Extrusive Igneous rocks are formed on Earths surface due to lava quickly cooling or mixing with different materials such as ash or cinders from an eruption. There are two different types of extrusive igneous rocks; Plutonic and Volcanic. Andesite is known for being gray in color and being made up of very coarse grainy textures, which make it much harder to break down than sedimentary rocks. Unlike loose gravel and other sediments igneous rocks are known for being able to slow down seismic waves from earthquakes which cause less damage to surface structures.
Plummer, C.C., McGeary, D., and Carlson, D.H., 2003, Physical geology (10th Ed.): McGraw-Hill, Boston, 580 p.
and Metamorphic rocks can be found. There are also a lot of crusted plates, and violent
Chondrules make up a large portion of chondrites. The millimeter-sized spherical objects originated as molten droplets in space. Most chondrules are rich in olivine and pyroxene. Chondrites also contain refractory inclusions (including Ca-Al Inclusions), which are among the oldest objects to form in the solar system, particles rich in metallic Fe-Ni and sulfides, and isolated grains of silicate minerals. The remainder of chondrites consists of fine-grained dust, which is either present in the matrix of the rock or forms rims or mantles around individual chondrules and refractory inclusions[11]. The geologic and cosmologic communities generally accepts that these spheres were formed by the action of a shock wave that passed through the Solar System, although there is little agreement as to the cause of this shock wave.[12]
Gould, S.J., & Vrba, E.S. 1982. Exaptation- a missing term in the science of form. Paleobiology, 8(1): 4-15.
If the cone is made up entirely of rock debris, we found very high gradient for the space occupied by the base. Here we find the gradient of 30 degrees and sometimes up to 40 degrees Celsius and these forms usually arise as a result of volcanic eruptions and represented in the islands in Indonesia.
It is composed of two elements; oxygen and sulfur. This mineral can either be white in colour, gray, brown, orange, green, red, pink, yellow, beige, or it can be colourless, and the streak that it leaves is white. Based on the Moh’s Hardness scale, Gypsum falls somewhere around the 2 margin. Its lustre is close to that of glass (in properties and in appearance), and is considered vitreous. The cleavage—where it breaks along its line of weakness—is 1,1 – micaceous ; 2,2 and its fracture is uneven. Gypsum is slightly flexible, has low hardness, where it can be scratched by a fingernail, and is sectile (can be cut with a knife). Gypsum is a sedimentary rock, meaning it was formed by cementation at the surface of the Earth near bodies of water; it causes the mineral (gypsum) to settle within the
It is composed of two elements; oxygen and sulfur. This mineral can either be white in colour, gray, brown, orange, green, red, pink, yellow, beige, or it can be colourless, and the streak that it leaves is white. Based on the Moh’s Hardness scale, Gypsum falls somewhere around the 2 margin. Its lustre is close to that of glass (in properties and in appearance), and is considered vitreous. The cleavage—where it breaks along its line of weakness—is 1,1 – micaceous ; 2,2 and its fracture is uneven. Gypsum is slightly flexible, has low hardness, where it can be scratched by a fingernail, and is sectile (can be cut with a knife). Gypsum is a sedimentary rock, meaning it was formed by cementation at the surface of the Earth near bodies of water; it causes the mineral (gypsum) to settle within the
There are two types of Igneous rocks. The first is intrusive, which is when the magma slowly cools beneath the earths surface. Because the magma is cooling slowly it allows the rocks end result to form crystal- like pigments. Examples of intrusive igneous rocks are Diorite, Gabbro, Granite, Pegmatite, and Periodotite. All of these rocks are course and grainy. The other type is an extrusive Igneous rock. This lava erupts onto the surface of the earth and cools rapidly also forming crystals, the lava cools so fast that at times it allows the rocks to form as clear-like glass. Examples of these rocks are Andesite, Basalt, Obsidian, Pumice, Rhyolite, Scoria,
As a result of this process, the mine sites "do not develop normal soil structure or support the establishment of a plant cover". Many mine sites have...