♥TIDES♥

Moon Tides
How The Moon Affects Ocean Tides...

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The word "tides" is a generic term used to define the alternating rise and fall in sea level with respect to the land, produced by the gravitational attraction of the moon and the sun. To a much smaller extent, tides also occur in large lakes, the atmosphere, and within the solid crust of the earth, acted upon by these same gravitational forces of the moon and sun. What are Lunar Tides Tides are created because the Earth and the moon are attracted to each other, just like magnets are attracted to each other. The moon tries to pull at anything on the Earth to bring it closer. But, the Earth is able to hold onto everything except the water. Since the water is always moving, the Earth cannot hold onto it, and the moon is able to pull at it. Each day, there are two high tides and two low tides. The ocean is constantly moving from high tide to low tide, and then back to high tide. There is about 12 hours and 25 minutes between the two high tides.
	Tides are the periodic rise and falling of large bodies of water. Winds and currents move the surface water causing waves. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side). Ocean levels fluctuate daily as the sun, moon and earth interact. As the moon travels around the earth and as they, together, travel around the sun, the combined gravitational forces cause the world's oceans to rise and fall. Since the earth is rotating while this is happening, two tides occur each day.
What are the different types of Tides When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides which are called spring tides, though they have nothing to do with the season. When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as dramatically high and low. These are called neap tides.

Spring Tides When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide. Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon. Neap Tides During the moon's quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide. Neap tides are especially weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.

The Proxigean Spring Tide is a rare, unusually high tide. This very high tide occurs when the moon is both unusually close to the Earth (at its closest perigee, called the proxigee) and in the New Moon phase (when the Moon is between the Sun and the Earth). The proxigean spring tide occurs at most once every 1.5 years.

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High Tide / Low Tide Examples
	A view of the tides at Halls Harbour on Nova Scotia's Bay of Fundy. This is a time lapse of the tidal rise and fall over a period of six and a half hours. During the next six hours of ebb the fishermen unload their boats on the dock. That's a high tide every 12 and 1/2 hours! There are two high tides every 25 hours.

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A Few Facts About Lunar Tides

The gravitational force of the moon is one ten-millionth that of earth, but when you combine other forces such as the earth's centrifugal force created by its spin, you get tides. The sun's gravitational force on the earth is only 46 percent that of the moon. Making the moon the single most important factor for the creation of tides. The sun's gravity also produces tides. But since the forces are smaller, as compared to the moon, the effects are greatly decreased. Tides are not caused by the direct pull of the moon's gravity. The moon is pulling upwards on the water while the earth is pulling downward. Slight advantage to the moon and thus we have tides. Whenever the Moon, Earth and Sun are aligned, the gravitational pull of the sun adds to that of the moon causing maximum tides. Spring tides happen when the sun and moon are on the same side of the earth (New Moon) or when the sun and moon are on opposite sides of the earth (Full Moon). When the Moon is at first quarter or last quarter phase (meaning that it is located at right angles to the Earth-Sun line), the Sun and Moon interfere with each other in producing tidal bulges and tides are generally weaker; these are called neap tides. Spring tides and neap tide levels are about 20% higher or lower than average. Offshore, in the deep ocean, the difference in tides is usually less than 1.6 feet The surf grows when it approaches a beach, and the tide increases. In bays and estuaries, this effect is amplified. (In the Bay of Fundy, tides have a range of 44.6 ft.) The highest tides in the world are at the Bay of Fundy in Nova Scotia, Canada. Because the earth rotates on its axis the moon completes one orbit in our sky every 25 hours (Not to be confused with moon's 27 day orbit around the earth), we get two tidal peaks as well as two tidal troughs. These events are separated by about 12 hours. Since the moon moves around the Earth, it is not always in the same place at the same time each day. So, each day, the times for high and low tides change by 50 minutes. The type of gravitational force that causes tides is know as "Tractive" force. FAQs About Lunar Tides From - "The Astronomy Cafe" Why are there no ocean tides at the equator? "Tides are a very complex phenomenon. For any particular location, their height and fluctuation in time depends to varying degrees on the location of the Sun and the Moon, and to the details of the shape of the beach, coastline, coastline depth and prevailing ocean currents. The tidal bulge of the Moon follows along the path on the earth's surface which intersects with the orbital plane of the Moon. This plane is tilted about 23 degrees with respect to the equatorial plane of the earth. The result is that near the equator, the difference between high tide and low tide is actually rather small, compared to other latitudes. To see this, draw a circle inscribed in an ellipse, with the major axis of the ellipse rotated by 23 degrees with respect to the circle's horizontal diameter. Now measure the height of the elliptical contour just above the 'equator' of the circle. You will see that it is quite small compared to other positions on earth, particularly at latitudes of 23 degrees or so. Even larger differences can occur depending on the shape of a bay or inlet or continental shelf." - Dr. Odenwald's ASK THE ASTRONOMER Why are ocean tides so different everywhere? "Because they depend on many factors including the geometry of your local coastline, and exactly where the Sun and Moon are located. Also, like the surface of a vibrating drum, the world oceans have vibratory modes that get stimulated in changing ways from minute to minute. Finally, there are storms at sea and elsewhere which move large quantities of water. Detailed forecasts are available for high and low tides in all sea ports." - Dr. Odenwald's ASK THE ASTRONOMER Why aren't the Atlantic and Pacific coast tides the same? "The nature of tides on the Earth's oceans is very complex. The oceans are, of course, being periodically 'forced' by a number of tidal sources including the Moon and the Sun, but this forcing has a number of different periods and harmonics. The two dominant periods are sue to the Sun and Moon, these are referred to as the S1 and M2 'modes' which have roughly 12 hour periods because they raise TWO water tides on the ocean diametrically opposite each other. But, for a variety of reasons, any given port will not have two high and two low tides each day; also called 'semi-diurnal tides'. A careful monitoring of the tides at any port for several years will show that in addition to the major modes, there are as many as 300 minor or 'harmonic' modes as well. The World Ocean is a complex dynamical system. The natural velocity of a water disturbance depends on the depth and salinity of the water at each point it passes. When bodies of land circumscribe bodies of water, they produce a collection of resonating systems that favor water oscillations with certain frequencies over others. From among the 300+ harmonics that can be measured, every port and coastal location has its own unique signature depending on its latitude, longitude, water depth and salinity. The result is that the 'two high two low' tide rule can be strongly modified so that the time between successive high tides can be greater than or less that 12 hours in many cases. The result is that for some locations, there can be days when only one high tide occurs. Looking at the Atlantic and Pacific Coast tide tables for 1995, the data for the various 'Standard Ports' showed that virtually all days had two high tides and two low tides in San Diego, San Francisco, New York and Charleston. There were, however a few days every few months when only a single high tide occurred." - Dr. Odenwald's ASK THE ASTRONOMER What is a Proxigean Spring Tide? "The Moon follows an elliptical path around the Earth which has a perigee distance of 356,400 kilometers, which is about 92.7 percent of its mean distance. Because tidal forces vary as the third power of distance, this little 8 percent change translates into 25 percent increase in the tide- producing ability of the Moon upon the Earth. If the lunar perigee occurs when the Moon is between the Sun and the Earth, it produces unusually high Spring high tides. When it occurs on the opposite side from the Earth that where the Sun is located ( during full moon) it produces unusually low, Neap Tides. The High, High Tide is called the Proxigean Spring Tide and it occurs not more than once every 1.5 years. Some occurrences are more favorable that others. A very interesting book "Tidal Dynamics" by Fergus J. Wood, published in 1986 by Reidel Publishing Company, talks at great length about these tides, and their environmental consequences. Because of the gravitational nature of the interaction between the Earth, the Moon, and the water on the Earth, there is a curious amplification event called 'evection' that occurs when the Moon is at its closest 'perigee' distance called its 'proxigee'. The Moon draws even closer to the Earth than its ordinary perigee distance. Because of the complex dynamics of the Earth's oceans, their inertia, friction with the ocean floor, internal viscosity and the distribution of the continents, the maximum tides do not always coincide with the optimal times of proxigee. Still, these tides can produce enormous damage when all factors come together optimally. There are many recorded instances of unusually high storm or coastal flooding during the proxigean times. On January 9, 1974 the Los Angeles Times reported 'Giant Waves Pound Southland Coast". During the last 400 years, there have been 39 instances or 'Extreme Proxigean Spring Tides' where the tide-producing severity has been near the theoretical maximum. The last one of these was on March 7 1995 at 22:00 hours Greenwich Civil Time during a lunar Full Moon. There were, in fact cases of extreme tidal flooding recorded during these particular spring tides which occur once every 31 years." - Dr. Odenwald's ASK THE ASTRONOMER If the Moon were to escape, what would happen to the Earth's oceans? "What happens is that the lunar water tides on the Earth go away, but the solar water tides still occur, but with about 1/3 or so the amplitude. There are still daily high and low tides, but they would be noticeably smaller. There would be no 'Spring' or 'Neap' tides, however."- Dr. Odenwald's ASK THE ASTRONOMER Why does the Moon produce TWO water tides on the Earth and not just one? "It is intuitively easy to understand why the gravitational pull of the Moon should produce a water tide on the Earth in the part of the ocean closest to the moon along the line connecting the center of the Moon with the center of the Earth. But in fact not one but TWO water tides are produced under which the Earth rotates every day to produce about two high tides and two low tides every day. How come? It is not the gravitational force that is doing it, but the change in the gravitational force across the body of the Earth. If you were to plot the pattern of the Moon's 'tidal' gravitational force added to the Earth's own gravitational force, at the Earth's surface, you would be able to resolve the force vectors at different latitudes and longitudes into a radial component directed towards the Earth's center, and a component tangential to the Earth's surface. On the side nearest the moon, the 'differential' gravitational force is directed toward the Moon showing that for particles on the Earth's surface, they are being tugged slightly towards the Moon because the force of the Moon is slightly stronger at the Earth's surface than at the Earth's center which is an additional 6300 kilometers from the Moon. On the far side of the Earth, the Moon is tugging on the center of the Earth slightly stronger than it is on the far surface, so the resultant force vector is directed away from the Earth's center. The net result of this is that the Earth gets deformed into a slightly squashed, ellipsoidal shape due to these tidal forces. This happens because if we resolve the tidal forces at each point on the Earth into a local vertical and horizontal component, the horizontal components are not zero, and are directed towards the two points along the line connecting the Earth and the Moon's centers. These horizontal forces cause rock and water to feel a gravitational force which results in the flow of rock and water into the 'tidal bulges'. There will be exactly two of these bulges. At exactly the positions of the tidal bulges where the Moon is at the zenith and at the nadir positions, there are no horizontal tidal forces and the flow stops. The water gets piled up, and the only effect is to slightly lower the weight of the water along the vertical direction. Another way of thinking about this is that the gravitational force of the Moon causes the Earth to accelerate slightly towards the Moon causing the water to get pulled towards the Moon faster than the solid rock on the side nearest the Moon. On the far side, the solid Earth 'leaves behind' some of the water which is not as strongly accelerated towards the Moon as the Earth is. This produces the bulge on the 'back side' of the Earth."- Dr. Odenwald's ASK THE ASTRONOMER What Causes Tides? "There are several kinds of tides. The ones that break upon a beach every 10 seconds to a minute are caused by sea level disturbances out in the ocean produced by such things as storms. Also, the various circulation currents of sea water can have velocity components directed towards the land which will bring water up onto the beach. As this water travels towards the beach from deep water to shallow water, its amplitude will increase until it finally 'breaks' as a full-fledged breaker, suitable for surfing etc. Now, underlying this minute to minute activity is a slower water wave which causes an alternating pattern of high-tide, low-tide, high-tide, low-tide in most places on the Earth that are directly on the ocean. This roughly 6 hour cycle is caused by the gravitational tugging of the Moon upon the Earth. This 'tidal' pull causes the shape of the solid Earth to be not perfectly round by something like a few dozen yards over its entire 27,000 mile circumference. The Earth gets distorted a small bit, but because it is solid rock its a small effect. The water in the oceans, however, gets distorted into a roughly ellipsoidal ( football-like) shape with a much larger amplitude. The orientation of this shape changes from minute to minute as the Moon orbits the Earth, which is why the high and low tide times change all the time. The Moon causes these tides by deforming the oceans, and as the Earth rotates under this ocean bulge, it causes a high tide to propagate onto beaches. Because there are two bulges, we get two high tides, and also two low tides each day. The Sun also causes tides on the Earth because even though it is so far away, it is very massive. These solar tides are about half as strong as the ones produced by the Moon, and they cause the so-called Spring tides and the Neap Tides. When the bulge of ocean water raised by the Moon is added the a similar tidal bulge raised by the Sun, you get a higher, high tide called the Spring Tide. When the solar low tide is added to the lunar low tide, you get the Neap Tide. There may be even weaker tides caused by the gravitational influences of the planets Mars and Venus, but they are probably lost in the daily noise of individual tides."- Dr. Odenwald's ASK THE ASTRONOMER When the Earth, Moon and Sun are aligned for Spring Tides, are they highest at Full or New Moon? "Spring tides are about the same height whether at New or Full Moon, because the tidal bulge occurs on both sides of the Earth...the side toward the Moon ( or sun) and the side away from the Moon (or Sun). They will not be equally high because the distance between the Earth and Sun, and the Earth and Moon both vary and so will their tide producing effectiveness. The highest Spring tides occur when the Moon is at its closest to the Earth...the so-called Perigee Tide."- Dr. Odenwald's ASK THE ASTRONOMER

♥EARTH AS IT REVOLVES AROUND THE SUN♥

The Seasons

The Earth

In space, the Earth's axis is tilted.

The Earth rotates on its axis.
It rotates once every 24 hours or 1 day.
The Earth's rotation creates day and night.

The Earth revolves around the Sun.
It takes 1 year for it to revolve all the way around.
One year also equals 12 months or 365 days.

The tilt of the Earth causes the seasons.
As the Earth orbits the Sun,
the tilt of the Earth's axis does not change.
The Earth always leans in the same direction.

When the North Pole is titled toward the Sun
during Summer, the North Hemisphere gets direct light.
The air in the atmosphere then becomes hot.

When the North Pole is titled away from the Sun
during Winter, the North Hemisphere gets indirect light.
The air in the atmosphere then becomes cold.

The Autumnal Equinox arrives on September 22 or 23.
On the first day of Autumn,
the sun's light is directly over the Equator.
This causes us to have an equal number
of hours of light and darkness.

The Winter Solstice arrives on December 21 or 22.
The North Pole is tilting far away from the Sun.
The first day of Winter is the shortest day of the year.
Because the Sun is lower in the sky,
the days are shorter and colder.

The Vernal Equinox arrives on March 20 or 21.
On the first day of Spring,
the Sun's light is directly over the Equator.
There are an equal number
of hours of daylight and darkness.

The Summer Solstice arrives on June 20 or 21.
The North Pole is as close to the Sun as it will get.
The first day of Summer is the longest day of the year.
Because the Sun is higher in the sky,
the days are longer and hotter.

♥EARHT ROTATES AROUND AN IMAGINARY AXIS ♥

Lecture 2 Theory of the Tropics Earth & Solar Geometry, Celestial Mechanics The geometrical relationship between the earth and sun is responsible for the earth's climates. The two principal movements of the earth are rotation and revolution.
Celestial Mechanics Revolution is the movement of the earth in an elliptical orbit around the sun whose average distance is 93 million miles away. The time to travel 1 orbit = 1 year. During this time there are 365.25 rotations of the earth.
Rotation is the movement of the earth around an imaginary axis (north and south pole). The rotation is complete in 24 hours producing night and day in non-polar regions. The angle of rotation is toward the East. Thus the sun, moon, and stars rise in the East and set in the West. The rotation also effects wind direction (e.g. easterly trade winds) and ocean currents.
Tilt of the Earth (Inclination of the Earth's Axis) The axis of the earth's rotation is inclined 66.5 degrees from the plain of the ecliptic or 23.5 degrees from an imaginary line vertical to it. The angle of inclination of the earth's axis is constant; this is known as the parallelism of the axis.
Distribution of Solar Energy A number of factors affect the distribution of solar energy over the earth and are responsible for night and day and the change in seasons. Degree of inclination of the earth's axis Parallelism of that axis The Earth's spherical shape Rotation of the Earth on its axis, Variation in altitude of the land surface
Oblique solar rays deliver less energy at the earth's surface than vertical rays, both because their energy is spread over a larger surface (top), and because they pass through a thicker layer of reflecting and absorbing atmosphere (bottom).
Seasons & Daylength Without the inclination of the earth there would be no seasons. Daylength would be exactly 12 hr light and 12 hr dark except at 0º when the sun would always be at the horizon. At Lafayette Indiana the sun would be always 40º from the zenith (directly overhead) at noon.
Seasonal time (solstice and equinox) is based on the geometry of the earth in relation to the sun during its yearly revolution. Solstice. The date the sun stands still on its N-S migration. Because of the inclination of the earth's axis the sun at its zenith is directly overhead at 23.5º N on June 21 (the summer solstice) and directly overhead at 23.5º S on December 21 (Winter solstice). Equinox. Refers to date of equal night and day period. This is the date when the sun at noon is directly overhead at the equator (March 21 = vernal equinox in the N hemisphere and September 23 = autumnal equinox in the N hemisphere)
At the times of the two equinoxes, then the sun's noon rays are vertical at the equator, the circle of illumination cuts all parallels in half, so that days and nights are equal (12 hr) over the whole earth.
At the times of the solstices, the sun's vertical noon rays have reached their greatest poleward displacement, 23.5º north or south. The circle of illumination then cuts all parallels except the equator unequally, so that days and nights are unequal in length except at latitude 0º.
Daylength Latitude Shortest day Longest day Tropics 0 12:07 12:07 10 11:32 12:42 20 10:56 13:20 Temperate 30 10:14 14:04 40 9:20 14:00 50 8:05 16:21 60 5:54 18:49 Polar 70 0:00 24:00 80 0:00 24:00 90 0:00 24:00
Length of Day in Various Northern Latitudes Month 0º 10º 20º 30º 40º 50º 60º 70º 80º 90º January 12:07 11:35 11:02 10:24 9:37 8:30 6:38 0:00 0:00 0:00 February 12:07 11:49 11:21 11:10 10:42 10:07 9:11 7:20 0:00 0:00 March 12:07 12:04 12:00 11:57 11:53 11:48 11:41 11:28 10:52 0:00 April 12:07 12:21 12:36 12:53 13:14 13:44 14:31 16:06 24:00 24:00 May 12:07 12:34 13:04 13:38 14:22 15:22 17:04 22:13 24:00 24:00 June 12:07 12:42 13:20 14:04 15:00 16:21 18:49 24:00 24:00 24:00 July 12:07 12:40 13:16 13:56 14:49 15:38 17:31 24:00 24:00 24:00 August 12:07 12:28 12:50 13:16 13:48 14:33 15:46 18:26 24:00 24:00 September 12:07 12:12 12:17 12:23 12:31 12:42 13:00 13:34 15:16 24:00 October 12:07 11:55 11:42 11:28 11:10 10:47 10:11 9:03 5:10 0:00 November 12:07 11:40 11:12 10:40 10:01 9:06 7:37 3:06 0:00 0:00 December 12:07 11:32 10:56 10:14 9:20 8:05 5:54 0:00 0:00 0:00
The Tropics The tropic (= turning) is a place where the sun is directly overhead during its N-S migration at the time of the turning. This is 23.5º N and 23.5º S. The names of the tropics (place or band around the earth) is: Tropic of Cancer (23.5º N) Tropic of Capricorn (23.5º S)
These names are based on the time of the disappearance of constellations (Cancer = crab; and Capricorn = horned goat) in the heavens in Babylonia (30º N).

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♥MOVING EARTH♥

The Moving Earth

The moving Earth. Image courtesy of Corel Corporation.

Even though we cannot sense it, the Earth is constantly in motion. In fact, the Earth isn't just moving, it's moving really fast! The fact that we do not feel as if we are moving led people to believe that the Earth is the stationary center of the universe for centuries. Eventually, astronomers discovered that the only way to explain all of the motions they observed in the sky was if the Earth were really moving. From their observations of the sky, they realized that there are two components to the Earth's motion; the Earth is orbitting the Sun, and the Earth is spinning like a top.

♥METAMORPHIC ROCKS♥

Geology - Chapter 7: Metamorphic Rocks Metamorphic rocks are probably the least understood by someone not familiar with geology. These rocks form from the deformation of previously existing igneous, sedimentary, and even an older metamorphic rock. The term metamorphic comes from a Greek term that means "change form."

Lesson Plan Monday - Read Text Tuesday - Research Wednesday - Quiz Thursday - Review Friday - Test

Parents Information This lesson plan is designed so that your child can complete the chapter in five days. The only decisions you will need to make will be concerning the research task for Tuesday. It is up to you to determine if the student will simply fill in the answers, or provide a short essay answer. You will also need to determine the percentage that this research will play in the overall chapter grade, if any.

General Principles Deep under the earth's surface, the temperature and pressure that rocks are subjected to can sometimes cause the rocks to change. This change can result in the partial or complete recrystallization of the minerals in a rock, and it can also fold or twist the rock so that it appears bent from its original shape. Rocks undergoing metamorphism mostly remain solid, and do retain some characteristics of their former rock. Their final structure, texture and composition are somewhat controlled by the original rock composition. To get a good understanding of this, let's start out with an animation that shows metamorphic rock formation. Click here to watch this animation. In the example, an igneous rock named diorite is subjected to heat and pressure. Note that the diorite has randomly oriented grains. You can see the individual grains becoming flatter as they are squeezed. The metamorphic rock formed is called gneiss. Notice that the grains are now foliated. This means that the platy (crystals squeezed flat) or elongated crystals are oriented with their axes perpendicular to the direction of the force. The resulting rock is foliated. Another term used for foliation is "banding." One concept that is important to understand is called plastic deformation. When a rock undergoes plastic deformation, that means that it can be twisted or folded without breaking. Even though a rock may seem like a rigid object, when subjected to heat and pressure, it can bend. This occurs with many metamorphic rocks. You will study this process in more detail in a later chapter. Because of the intense heat and pressure, much of the rocks in the earth's crust are probably metamorphic. They are formed deep beneath the earth's surface by high pressures and temperatures. They can also be formed from the intrusion of magma, which heats the surrounding rock and metamorphoses it. How the Process Works Metamorphism has three major forces that effect the changes to the rock. These forces are temperature, pressure, and chemistry. As the temperature of the rock climbs, melting begins to occur, filling in the pore spaces of the rock. Typically, rocks below 200 degrees centigrade only have a small amount of pore fluid present. Between 200 and 700 degrees centigrade, the rocks become more fluid...chemical reactions occur more frequently, and new mineral assemblages appear. Above 700 degrees, the rock can take on magma-like properties, leading some rocks to appear as if they have layers of igneous and metamorphic rocks. The next most important force acting upon rocks is pressure. This can be pressure from overlying layers of rock, or pressure from rising bodies of magma, or pressure from tectonic forces. The most significant effect of pressure is that it compacts the amount of space occupied by the rock. As mentioned previously, the pressure can produce foliation, which tells geologists the direction of force applied to produce the metamorphic rock. The pressure and temperature rises can free many atoms and molecules from their crystal structure. These free atoms/molecules provide both a transport system for materials to move about the rock matrix, and they provide new material for crystallizing new minerals. This process is called recrystallization. Plate Tectonics and Metamorphic Rocks The process of forming metamorphic rocks is intimately associated with plate tectonics. Because many of these processes occur many miles beneath the surface of the earth, we cannot observe this process in action. We can, however, test how minerals respond to heat and pressure in a laboratory, and together with field observation, come up with scientific explanations for how the rocks formed. There are two type of metamorphic processes. When a body of magma rises through the crust, it heats the surrounding rock that it passes through. This heat causes the rock to metamorphose. This type of metamorphism is called contact metamorphism. The changes may occur through the partial melting of the rock, or it may occur through chemical changes. Elements can be added or taken way by fluids entering or leaving the rock. Contact metamorphic rocks are commonly associated with batholiths, and they are commonly found around dikes and sills. The second type of process, and much more prevalent, is called regional metamorphism. A large part of our continental crust is made up of metamorphic rocks. When tectonic plates collide, the pressure and heat from this collision produces metamorphic rocks, which can affect many cubic miles of crustal material. The colliding plates can also cause the rock layers to fold, creating interesting rock features. Examine the folded rocks in the picture. This is a small-scale picture showing an area of rock about 7 by 10 inches. Much larger scale folds can also be observed. Metamorphic Rocks Like igneous rocks, metamorphic rocks are classified based on texture and composition. There are two basic types of texture for a metamorphic rock. Rocks which exhibit foliation are said to exhibit a planar texture. Planar texture can further be divided based on the type/degree of foliation. Rocks which do not show foliation are said to exhibit a granular texture. Granular texture is sometimes called non-foliated. This can be confusing, since planar texture rocks has grains that you can see. If it exhibits foliation, it is not granular texture...even if it exhibits grains. Planar Texture Rocks Slate - Slate is a fine-grained metamorphic rock. The source rock prior to metamorphism is the sedimentary rock shale. Slate is a foliated rock which breaks off in sheets. It is said to have "slaty cleavage." It is the result of low-grade metamorphism. It has many economical uses Schist - Schist is a medium-grade metamorphic rock which is also foliated. In a schist, the parallel arrangement of large grains of platy minerals such as mica, chlorite, talc, or hematite is called schistosity. These grains are large enough to be seen with the naked eye. The original rock prior to metamorphism could be shale, basalt, granite, sandstone, and tuff, to name a few. A common type of schist is called garnet schist (bottom picture). Crystals of the mineral garnet form during the metamorphic process A public domain picture of a garnet schist is needed. If you would like to donate one, please email. Gneiss - Gneiss is a course-grained metamorphic rock. It contains gneissic layering, where the foliation results in layers of alternating light and dark minerals. The composition is typically like that of granite. Gneiss forms from high-grade metamorphism. Granular Texture Rocks Quartzite - Quartzite is a hard metamorphic rock. The original source rock prior to metamorphism is sandstone. Pure quartzite is white to grey, but other colors can occur. Marble - Marble is a metamorphic rock which can result from regional or contact metamorphism. The original source rock is limestone. Marble has many economic uses. Amphibolite - This metamorphic rock is a course-grained rock composed of amphibole and plagioclase, although other minerals may be present. The original source rock prior to metamorphism is basalt, gabbro, and other rocks with iron and magnesium. A public domain picture of an amphibolite is needed. If you would like to donate one, please email. Metaconglomerate - This is simply a conglomerate that has undergone metamorphism. It illustrates the ability of a rock to bend without breaking. The original grains were well-rounded pebbles, and they are squeezed flat Hornfels - A hornfel is a very fine-grained, non-foliated metamorphic rock that is hard and dense. It results from high temperature contact with an intrusive igneous rock body. Source rocks prior to metamorphism include sandstone, shales, and limestones, among others. A public domain picture of a hornfel is needed. If you would like to donate one, please email. Summary As a final tool to tie this all together, please examine this excellent website with animations concerning Metamorphic Rocks and Plate Tectonics. Tuesday - Research Research the answers to the following questions about metamorphic rocks. Your parents may have you simply answer the questions, or they may have you put it in essay form. Please follow your parents instructions. To answer these questions, utilize a search engine to locate the best web pages, or consult a textbook/encyclopedia. You may also use the links at the bottom of this page. What are the economic uses of metamorphic rocks? What are some of the historical items that have been constructed with metamorphic rocks. Wednesday - Quiz Today you will complete an 10 question practice quiz. The link to the quiz will open a new window. You can come back here and check your answers. Do not click the Back button on your browser during the quiz. After the quiz, continue your research project, if necessary. Geology Chapter 7 Quiz Thursday - Review Please review the terms in bold in the text, and ensure you have completed your research work from Tuesday. Friday - Test Today you will take the end of chapter test. Please close all other browser windows, and click on the link below. During the test, do not click on the Back button on your browser. Geology Chapter 7 Test After you have completed the test, you may proceed to Chapter 8 on your next school day. Please return to the introduction page for the link to the next chapter. Return to the Answers In Creation Online Geology Curriculum homepage.

♥MINERALS FROM ROCKS♥

Rocks and Minerals

The rocks and minerals pictured above are from different parts of Kansas. Click on a sample to find out more.

The rocks and minerals found above and below ground in Kansas have long been important to the state's residents. In addition to their economic importance (click here to read more about rocks, minerals, and petroleum resources), the state's rocks and minerals are also valued for their intrinsic beauty and appearance.

• Mineral Identification
• Mineral Hardness Scale

Geologic Regions

General geology, rocks and minerals, and places to visit in the state's physiographic regions (including PDF factsheets for downloading)

Fossils

Summaries of common Kansas fossils

Places to Visit

Photos and descriptions of sites of geologic (and other) interest in Kansas

Rocks and Minerals

Descriptions of various rocks and minerals found in Kansas, including mineral ID tables and hardness scale

Geo Topics

Overviews of various geology topics, ranging from Earth's age to the state's mining history

Field Trips

Online guidebooks, descriptions, and photos from KGS public field trips in Kansas

Sedimentary Rocks Picture Gallery of the Most Common Rock Types Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks: 1) clastic sedimentary rocks such as breccia, conglomerate, sandstone and shale, that are formed from mechanical weathering debris; 2) chemical sedimentary rocks such as rock salt and some limestones, that form when dissolved materials precipitate from solution; and, 3) organic sedimentary rocks such as coal and some limestones which form from the accumulation of plant or animal debris. Pictures and brief descriptions of some common sedimentary rock types are shown below. Sedimentary Rock Types Menu Breccia Chert Coal Conglomerate Iron Ore Limestone Rock Salt Sandstone Shale Siltstone Breccia Breccia is a clastic sedimentary rock that is composed of large (over two millimeter diameter) angular fragments. The spaces between the large fragments can be filled with a matrix of smaller particles or a mineral cement which binds the rock together. The specimen shown above is about two inches (five centimeters) across. Return to Top Chert Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO2). It occurs as nodules and concretionary masses and less frequently as a layered deposit. It breaks with a conchoidal fracture, often producing very sharp edges. Early people took advantage of how chert breaks and used it to fashion cutting tools and weapons. The specimen shown above is about two inches (five centimeters) across. Return to Top Coal Coal is an organic sedimentary rock that forms mainly from plant debris. The plant debris usually accumulates in a swamp environment. Coal is combustible and is often mined for use as a fuel. The specimen shown above is about two inches (five centimeters) across. Return to Top Conglomerate Conglomerate is a clastic sedimentary rock that contains large (greater then two millimeters in diameter) rounded particles. The space between the pebbles is generally filled with smaller particles and/or a chemical cement that binds the rock together. The specimen shown above is about two inches (five centimeters) across. Return to Top Iron Ore (Hematite) Iron Ore is a chemical sedimentary rock that forms when iron and oxygen (and sometimes other substances) combine in solution and deposit as a sediment. Hematite (shown above) is the most common sedimentary iron ore mineral. The specimen shown above is about two inches (five centimeters) across. Return to Top Limestone Limestone is a rock that is composed primarily of calcium carbonate. It can form organically from the accumulation of shell, coral, algal and fecal debris. It can also form chemically from the precipitation of calcium carbonate from lake or ocean water. Limestone is used in many ways. Some of the most common are: production of cement, crushed stone and acid neutralization. The specimen shown above is about two inches (five centimeters) across. Return to Top Rock Salt (Halite) Rock Salt is a chemical sedimentary rock that forms from the evaporation of ocean or saline lake waters. It is also known by the mineral name "halite". It is rarely found at Earth's surface, except in areas of very arid climate. It is often mined for use in the chemical industry or for use as a winter highway treatment. Some halite is processed for use as a seasoning for food. The specimen shown above is about two inches (five centimeters) across. Return to Top Sandstone Sandstone is a clastic sedimentary rock made up mainly of sand-size (1/16 to 2 millimeter diameter) weathering debris. Environments where large amounts of sand can accumulate include beaches, deserts, flood plains and deltas. The specimen shown above is about two inches (five centimeters) across. Return to Top Shale Shale is a clastic sedimentary rock that is made up of clay-size (less then 1/256 millimeter in diameter) weathering debris. It typically breaks into thin flat pieces. The specimen shown above is about two inches (five centimeters) across. Return to Top Siltstone Siltstone is a clastic sedimentary rock that forms from silt-size (between 1/256 and 1/16 millimeter diameter) weathering debris. The specimen shown above is about two inches (five centimeters) across. Return to Top

Coal by Microscope Coal Through a Microscope: Coal is more than a black rock. It's THE most interesting rock. Metamorphic Rocks Metamorphic Rock Photos: rocks modified by heat, pressure and chemical processes. Igneous Rocks Igneous Rock Photos: formed from the solidification of molten rock material. Sand Grains "A Grain of Sand": A gallery of sand grains from around the world as photographed through a microscope by Dr. Gary Greenberg. Mystery Rocks Sliding Rocks: How these rocks slide across a dry lake bed is a mystery. Learn what is thought to move them. © iStock / S. Hoerold Rock Art Petroglyphs and Pictographs: A world-wide collection of interesting rock art. © iStockphoto / K. Lange. Herkimer Diamonds Herkimer Diamonds: Learn how to find these doubly terminated quartz crystals at Herkimer, NY. Polishing Rocks Free Guide to Rock Tumbling: Step-by-step guide to tumble and polish rocks into gemstones. Spectacular Rockfall Spectacular Yosemite Rockfall: A photo sequence of the fall and debris avalanche by Herb Dunn. Gold The Many Uses of Gold: Learn how the unique properties of gold make it extremely suited for a large number of industrial uses. Space Rocks Meteorites: Learn about meteorites and how to identify them. Granite Uses of Granite: The rock used for everything from kitchen counters to street curbing to the facing stone of skyscrapers.

More Rock Collections: Metamorphic Rocks -- Igneous Rocks

More Rock Information From Geology.com Igneous Rocks Metamorphic Rocks Sedimentary Rocks Sliding Rocks of Racetrack Playa Spectacular Yosemite Rockfall Free Guide to Rock Tumbling Coal Through a Microscope Uses of Granite Petroglyphs and Pictographs Rocks and Minerals