Hello, everyone! You might want to know more about Christmas. Thank you for visiting my blog! Christmas is my favorite holiday. In Argentina, the weather is almost always warm at Christmas. Preparations for Christmas begin very early in December and … Continue reading
Hey there! I’m researching rocks because I’m curious about them. I also like rocks because they are so interesting. Enjoy!
Geologists define rocks as aggregate of minerals. Minerals are naturally occurring, not unhealthy substances with specific chemical compositions and structures. A rock can be filled of many crystals of one or more minerals, or combinations of many minerals. Several exceptions, such as coal and obsidian, are not composed of minerals but are thought to be rocks.
People often use rocks for include building materials, roofs, sculpture, jewelry, tombstones, chalk, coal for heat, and more. Oil and natural gas can also be found in rocks. Many metals like a fork are made from rocks known as ores. Even, prehistoric humans used rocks as early as 2,000,000 B.C. Flint and other hard rocks were very important raw materials for crafting arrowheads and other special natural made rocks.
Around 500,000 B.C., rock caves and structures made from stones had become important forms of shelter for early man. During that time, early men had learned to use fire, a development that allowed humans to cook food as needed to survive and greatly expand their geographical range. Eventually, most likely no sooner than 5000 B.C., humans had realized that minerals such as gold and copper could be from rocks. Tons of ancient monuments were crafted from stone, including the pyramids of Egypt, built from limestone about 2500 B.C., and the buildings of Chichen Itza in Mexico, also of limestone, built near A.D. 450.
Since the 1500s, scientists have studied minerals and mining, fundamental aspects of the study of rocks. Georg Bauer published Concerning Metallic Things in 1556. By 1785, the British geologist James Hutton published Theory of the Earth, in which he explained his observations of rocks in Great Britain and his conclusion that Earth is much older than previous scientists before him had guessed. Geologists are scientists who study the earth and rocks, distinguish three main groups of rocks: igneous rocks, sedimentary rocks, and metamorphic rocks.
These distinctions are made on the basis of the types of minerals in the rock, the shapes of individual mineral grains, and the overall texture of the rock, all of which indicate the environment, pressure, and temperature in which the rock was made. Igneous rocks form when magma is below the land of the Earth or lava at the land of the Earth hardens. The minerals in the rock will make crystals or grow together so that the separate crystals make 1 crystal altogether. Igneous rocks and magma make up much of the oceanic and continental crust, as well as most of the rock deeper in the Earth.
Igneous rocks can be identified by the interlocking appearance of the crystals in them. Typical igneous rocks do not have a layered texture, but exceptions exist. For example, in large bodies of igneous rock, relatively thick crystals that are made early can sink to the bottom of the magma, and less thick layers of crystals that are made later can accumulate on top. Igneous rocks can form deep within the Earth or at the surface of the Earth in volcanoes.
In general, igneous rocks that form deep within the Earth have large crystals that indicate a longer period of time during which the magma cools. Igneous rocks that form at or near the surface of the Earth, such as volcanic igneous rocks, cool quickly and contain smaller crystals that are difficult to see without magnification. Obsidian, also called volcanic glass, cools down so fast that no crystals are made. Nevertheless, obsidian is considered to be an igneous rock.
Igneous rocks are classified on the basis of how much minerals there are and the size of the crystals in the rock. Extrusive igneous rocks have small crystals and crystallize at or near the Earth’s surface. Intrusive igneous rocks cool slowly below the Earth’s surface and have larger crystals. Rocks made up of thick, dark-colored minerals like olivine, pyroxene, amphibole, and plagioclase are called mafic igneous rocks.
Light-colored, less thick minerals, including quartz, mica, and feldspar are called felsic igneous rocks. Common igneous rocks include the felsic igneous rocks granite and rhyolite, and the mafic igneous rocks gabbro and basalt. Granite is an intrusive igneous rock that includes large crystals of the minerals quartz, feldspar, mica, and amphibole that form deep within the Earth. Rhyolite includes the same minerals, but forms as extrusive igneous rock near the surface of the Earth or in volcanoes and cools quickly from magma or lava, so its crystals are difficult to observe with the naked eye.
Similarly, gabbro is more coarse-grained than basalt and made deeper down in the Earth, but both rocks include the minerals pyroxene, feldspar, and olivine. Fabulous exposures of igneous rocks occur in the volcanoes of Hawaii, volcanic rocks of Yellowstone National Park are located in Wyoming, Idaho, Montana, in Lassen Volcanic National Park and Yosemite National Park in California. Sedimentary rocks are those made of grains of preexisting rocks or organic material that, in most cases, have been eroded, deposited, compacted, and cemented together. They typically form at the surface of the Earth as sediment moves as a result of the action of wind, water, ice, gravity, or a combination of these.
Sedimentary rocks also form as chemicals precipitate from seawater, or through accumulation of organic material such as plant debris or animal shells. Common sedimentary rocks include shale, sandstone, limestone, and conglomerate. Sedimentary rocks typically have a layered appearance because most sediments are deposited in horizontal layers and are buried beneath later deposits of sediments over long periods of time. Sediments deposited rapidly, however, tend to be poorly layered if layers are visible at all.
Sedimentary rocks are made in many different environments at the surface of the Earth. Eolian, or wind blown, sediments can accumulate in deserts. Rivers carry sediments and deposit them along their banks or into lakes or oceans. Glaciers make unusual deposits of a wide variety of sediments that they pick up as the glacier expands and moves; glacial deposits are well exposed in the northern United States. Sediments can travel in currents below sea level to the deepest parts of the ocean floor.
Secretion of calcium carbonate shells by reef-building organisms produce large quantities of limestone. Evaporation of seawater has resulted in the formation of widespread layers of salt and gypsum. Swamps rich in plants can produce coal if organic material accumulates and is buried before aerobic bacteria can destroy the dead plants. Sedimentary rocks are classified on the basis of the sizes of the particles in the rock and the composition of the rock.
Clastic sedimentary rocks comprise fragments of preexisting rocks and minerals. Chemical precipitates are sedimentary rocks that are made by precipitation of minerals from seawater, salt lakes, or mineral-rich springs. Organic sedimentary rocks formed from organic matter or organic activity, such as coal and limestone made by reef-building organisms like coral. Grain sizes in sedimentary rocks range from fine clay and silt to sand to boulders.
The sediment in a sedimentary rock reflects its environment of deposition. For example, wind-blown sand grains commonly is evidence of abrasion of their surfaces as a result of colliding with other grains. Sediments transported long distances tend to decrease in size and are more rounded than sediment deposited near their precursor rocks because of wearing against other sediments or rocks. Large or heavy sediments tend to wear out of water or wind if the energy of the water or wind is insufficient to carry the sediments.
Sediments deposited rapidly as a result of slides or slumps tend to include a larger range of sediment sizes, from large boulders to pebbles to sand grains and flakes of clay. Such rocks are called conglomerate. Along beaches, the rhythmic activity of waves moving sediment back and forth produces sandstones in which the grains are well rounded and of similar size. Glaciers pick up and carry a wide variety of sediments and often scratch or scrape the rocks over which they travel.
Sedimentary rocks are the only rocks in which fossils can be preserved because at the elevated temperatures and pressures in which igneous and metamorphic rocks form, fossils and organic remnants are ruined. The presence of fossils and the types of fossil organisms in a rock provide clues about the environment and age of sedimentary rocks. For example, fossils of human beings are not present in rocks older than approximately two million years because humans did not exist before then. Similarly, dinosaur fossils do not occur in rocks younger than about 65 million years because dinosaurs became extinct at that very time.
Fish fossils in sedimentary rock indicate that the sediments that make up the rock were deposited in a lake, river, or marine environment. By establishing the environment of the fossils in a rock, scientists learn more about the conditions under which the rock formed.
Spectacular exposures of sedimentary rocks include the Grand Canyon which is in Arizona, the eolian sandstones of Zion National Park which is in Utah, the limestones of Carlsbad National Park which is in New Mexico, and glacial features of Voyageurs National Park which is in Minnesota. Metamorphic rocks are named for the process of change that affects rocks. The changes that make metamorphic rocks usually include rises in the temperature (generally to 392°F) and the pressure of a precursor rock, which can be igneous, sedimentary, or metamorphic, to a degree that the minerals in the rock are no longer stable. The rock might change in mineral content or appearance, or even both. Clues to identifying metamorphic rocks include the presence of minerals such as mica, amphibole, staurolite, and garnet, and layers in which minerals are aligned as a result of pressure applied to the rock.
Common metamorphic rocks include slate, schist, and gneiss. Metamorphic rocks commonly are made in mountains such as the Appalachian Mountains, parts of California, and the ancient, eroded metamorphic rocks in the Llano Uplift of central Texas. Metamorphic rocks are classified depending on their constituent minerals and texture. Foliated metamorphic rocks are those that have a layered texture. In foliated metamorphic rocks, elongate or platy minerals such as mica and amphibole become aligned as a result of pressure on the rock. Foliation can range from alternating layers of light and dark minerals typical of gneiss to the seemingly perfect alignment of platy minerals in slate.
Some metamorphic rocks aren’t foliated and have a massive texture devoid of layers. Mineralogy of metamorphic rocks reflects the mineral content of the precursor rock and the pressure and temperature at which metamorphism occurs. As sediments undergo metamorphism, the layers of sediment can be folded or become more pronounced as pressure on the rock increases. Elongate or platy minerals in the rock tend to become aligned in the same direction.
For example, when shale metamorphoses to slate, it becomes easier to split the well-aligned layers of the slate into thin, flat sheets. This property of slate makes it an attractive roofing material. Marble-metamorphosed limestone typically does not have the pronounced layers of slate, but is used for flooring and sculptures.
Metamorphism of igneous rocks can cause the different minerals in the rocks to separate into layers. When granite metamorphoses into gneiss, layers of light-colored minerals and dark-colored minerals form. As with sedimentary rocks, elongate or platy minerals become well-aligned as pressure on the rock increases.
As sediments undergo metamorphism, the layers of sediment can be folded or become more pronounced as pressure on the rock increases. Elongate or platy minerals in the rock tend to become aligned in the same direction. For example, when shale metamorphoses to slate, it becomes easier to split the well-aligned layers of the slate into thin, flat sheets. This property of slate makes it an attractive roofing material.
Marble-metamorphosed limestone-typically does not have the pronounced layers of slate, but is used for flooring and sculptures. Metamorphism of igneous rocks can cause the different minerals in the rocks to separate into layers. When granite metamorphoses into gneiss, layers of light-colored minerals and dark-colored minerals are made. As with sedimentary rocks, elongate or platy minerals become well-aligned as pressure on the rock increases.
It is possible for metamorphic rocks to change into other metamorphic rocks. In some regions, especially areas where mountain building is taking place, it is not unusual for several episodes of change to affect rocks. It can be difficult to unravel the effects of each episode of metamorphism. The word igneous comes from the Latin word ignis which means of fire. Sedimentary rocks make layers at the bottoms of oceans and lakes.
Layers of sedimentary rocks are called strata.
I got this photo at http://www.hydroponicsnewyorkcity.com/wp-content/uploads/2014/02/river-rocks.jpg but originally Google Images.
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Hi there! My mother, Camilla suggested that I write a series of posts about birds on my blog since I’ve been talking about them and learning about them. Please let me know if you have any bird books, CDs, or a website you’d recommend! Here is the part about American Tree Sparrows.
American Tree Sparrows are small, round-headed birds that often fluff out their feathers, making their plump bodies look even chubbier. Like other sparrows, they have fairly small bills and long, thin tails. Their color pattern is a rusty cap and rusty (not black) eyeline on a gray head, a streaked brown back, and a smooth gray to buff breast in both male and female American Tree Sparrows give an overall impression of reddish-brown and gray. A dark smudge in the center of the unstreaked breast is common.
Small flocks of American Tree Sparrows hop about on the ground, scrabbling for grass and weed seeds, calling back and forth with a soft, musical twitter that might make you twitter, sing, or dance. A single American Tree Sparrow may perch in the open top of goldenrod stalks or shrubs, or on low tree branches. Look for small flocks of American Tree Sparrows in the winter in weedy fields with hedgerows or shrubs, along forest edges, or near marshes except for Reno, NV. They readily visit backyards, especially if there’s a seed feeder.
American Tree Sparrows breed in the far north and are hardly seen south of northern Canada in the summer. 4-6, usually 5. Pale bluish or greenish, with brownish spotting often concentrated at larger end. Incubation is by female, 11-13 days; male visits nest often, but does not incubate. Young: Both parents feed nestlings. Young leave nest at age 8-10 days, when flight feathers not yet fully grown.
Parents may lure them away from nest by offering food. Young are able to fly at about 14-15 days after hatching; parents continue to feed them for about 2 more weeks. 1 brood per season, but may attempt to renest if 1st attempt fails. Diet in the winter is almost entirely seeds, from grasses, weeds, and other plants; also a few insects and berries.
In the summer, they eat mostly insects and other small invertebrates, plus a few seeds. Young are fed mostly insects. Pairs form shortly after birds arrive on breeding grounds. Male actively defends territory, chasing away other members of same species.
Nest site is on or near ground, in grass clumps beneath shrubs. Sometimes on hummock in open tundra; rarely up to 4′ above ground in willow or spruce. Nest is an open cup of twigs, grasses, moss, lined with fine grass and with feathers (usually ptarmigan feathers). Female builds nest in about 7 days.
All wintering areas are well to the south of breeding areas. Migrates relatively late in fall and early in spring. Apparently, migrates mainly at night. On average, females winter somewhat farther south than males.
The American Tree Sparrow is a small sparrow with a long notched tail. The adult has a streaked back and wings, with two white wing bars, but is otherwise unstreaked, while the juvenile is streaky overall. Adults have an unstreaked gray-brown breast and belly, with a dark spot in the center. The tail, rump, and nape of the neck are all solid gray.
The upper mandible of the bill is dark and the lower is yellow. The head is mostly gray, with a rufous crown and eye-line. American tree sparrows (Spizella arborea) breed throughout almost all of Alaska, the Yukon and Northwest territories, the very north of Manitoba and Ontario, all of Labrador, and in northern Quebec. Their winter range includes a very small part of southern Canada and all of the United States except for the western most 250 miles, the southern most 450 miles and all of Florida.
American tree sparrows usually breed near the tree line in open scrubby areas with willows, birches, alder thickets or stunted spruce. They may also breed in open tundra with scattered shrubs, often near lakes or bogs. They spend the winter in open forests, gardens, fields, and marshes. Baumgartner followed birds for the first 22 days of development.
Order of hatching was not dependent on the order of laying. Earlier hatched birds took the lead in development. During the nine and one-half days in the nest, the four feather tracts of the birds (dorsal, ventral, alar, caudal) go from completely bare to the back covered, lower belly slightly bare, wings 2/3 grown, and tail still a stub, and the birds grow from 1.62 gm to 16.7 gm, while their length goes from 33 mm to 75 mm during the same period. They lose 1.5 gm the first day out of the egg but have gained 3 gm by day 21 (Baumgartner, 1968).
On the second day after hatching the young were able to stretch for food. On the fourth day their eyes were half open, after the fifth day, wide open. The first sounds were made on the fifth day but were very soft. Fear was acquired between 7.5 and 8 days as demonstrated by their raucous calls when touched by humans.
During the first 12 days of the fledgling period (which lasts until about a month after leaving the nest in (Spizella arborea) the birds showed a steady increase in both tail length (14-47mm) and wing length (46-68mm). At the end of the first 21 days the wings were still slightly shorter and the tails about 2/3 the length of mature birds. A tree sparrow was observed to fly 30 or 40 ft fifteen days after hatching, and a little before one month after hatching, the birds could fly all around their territory. American tree sparrows are monogamous (one male mates with one female).
Males and females form breeding pairs after they arrive at the breeding sites in the spring. Both males and female sing to attract a mate. Females become excited when males come to sing nearby. They call back to the male, making a “wehy” sound.
Males may show off for females by spreading their wings and fluttering them or darting to the ground in front of the female, then flying back up to a perch. American tree sparrows breed between May and September. They raise one brood of chicks each year. The females builds the nest alone.
The nests are built on the ground out of moss, grasses, bark and twigs. They are lined with fine grass and feathers.The female then lays about 5 eggs. She lays one egg each day.
She incubates the eggs for 10 to 14 days and broods the chicks after they hatch. The chicks are altricial (helpless) when they hatch, so they rely on the female to protect them and keep them warm. Both parents feed the chicks until 2 to 3 weeks after the chicks leave the nest (called fledging). The young fledge from the nest about 9 days after hatching.
In late summer, the families join larger flocks. We do not know when young American tree sparrows begin breeding.
American tree sparrows breed once per year. Females incubate the eggs and brood the chicks after they hatch.
Both parents feed the chicks until they are about 22 days old. The oldest known American tree sparrow lived at least 10 years and 9 months. Most American tree sparrows probably live about 2.3 to 3.4 years. American tree sparrows are migratory.
Though they are usually active during the day (called diurnal), they migrate at night. American tree sparrows are territorial during the breeding season. Males sing to claim territories and they defend their territories from others. Females occasionally chase intruders too.
American tree sparrows do not defend winter territories. During the winter, they form large flocks that forage together. Within these flocks, some birds are dominant over other birds. American tree sparrows move by hopping on the ground and on branches, and by flying.
They do not swim or dive, but they do bath frequently. They roost alone trees or shrubs, haystacks, cornfields, and marshes. In the winter, they might take shelter together under the snow. American tree sparrows are omnivorous; they eat many different seeds, berries and insects.
During the winter, American tree sparrows mainly eat grass and weed seeds. During the summer, they mostly eat insects and spiders. American tree sparrows search for food among plants on the ground and the branches and twigs of shrubs and trees. In Massachusetts, they are often seen in flocks, feeding at bird feeders.
American tree sparrows need to drink a lot of water each day. During the winter, they eat snow in order to get enough water. Known predators of American tree sparrows include northern goshawks, sharp-shinned hawks, screech owls, pygmy owls, Cooper’s hawks, American kestrels, weasels, foxes, and red squirrels. When approached by humans, American tree sparrows give a rapid series of “tset” calls.
It is unknown how American tree sparrows respond to other potential predators. American tree sparrows are very important members of the food chain. They eat many weed seeds and insects and spiders, and they are an important food source for their predators.
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