Earth Science- Grace 8th grade

In Deltas and alluvial fans the largest pieces of sediment are located at the start/beginning of the fans and the smaller sediments are near the tips of the fans. Explain why this happens

As the water slows down the heavier sediments are laid down first. The slower moving water still can carry the smaller sediments. However, over time the sediments will be deposited as the ever slowing water is unable to suspend (hold) the sediments

Little Timmy loves rocks and he has heard the terms constructive and destructive forces being used a lot in class. However, Little Timmy takes his usual restroom break every time at the place where constructive and destructive forces were explained. Help Little Timmy out by explaining what these two forces are and provide an example of each.

Constructive - to make/form rocks examples: cooling/crystallization, deposition, compaction and cementation Destructive - to break/destroy rocks Examples: melting, weathering, erosion

If you were growing crops on a field near a slow-moving, curvy river, what would an advantage of the field's location? What might be a disadvantage?

Flooding will cause for the deposition of nutrient rich sediments which yield more bountiful crops. On the flip side, if the flooding occurs as the plants are growing, the crops could be destroyed.

How would glaciers be affected by changes in climate, such as global warming and global cooling?

Glaciers tend to grow in size during periods of cooling (ice ages) and during times of warming the glaciers tend to melt and some glaciers disappear altogether.

Annika often goes fishing at one of several small, round lakes that are within 20 miles of her house in Minnesota. State the name given to the lakes and explain how they formed?

The lakes likely formed when a chunk of glacial ice was deposited in a depression (hole) and melted. This new land feature is known as a kettle lake.

Each year Clark and his family visit the ocean. Clark notices that a sandbar near the coast is slightly larger each year. What is causing this to happen? What structure could the sandbar eventually become? Why are sandbars and dunes important to the health of beachfront communities

The longshore current allowing for longshore drifts which is allowing build-up of sand over time. Each time the current pushes by the sandbar more and more sand gets deposited. Eventually a barrier island may form. The sandbars and dunes protect against storm surges which ultimately keep the ocean out of the communities.

What is the Rock Cycle?

* It is the ongoing process that creates and changes rock. * Heat, pressure, erosion, weathering, compaction, cementation, melting and cooling allows rocks to change from one type of rock to another.

Constructive Forces

1. Cooling/Crystallization: The magma hardens back into solid rock. 2. Deposition leading to: *Compaction: sediments from eroded rocks lay on top of each other and pressure from upper layers pushes down on lower layers. * Cementation: large sediments can't stick together so the deposit of other minerals between the pieces of sediment hold it together.

Destructive Forces

1.Weathering: The wearing down of rocks by the actions of wind, water, ice and living things. - Examples: water freezing and breaking apart rocks, roots breaking apart rocks. 2.Erosion: The process of moving broken down rock from one place to another - Examples: wind blowing sand, river moving sediments. 3.Melting: Due to heat and pressure and friction, rocks under the earth's surface turn to magma

Kettle Lake-

A bowl-shaped depression that was formed by a block of ice that was left behind by a glacier and then became filled with water

What are Constructive Forces?

A constructive force is a force that puts rocks back together Examples: Cooling/Crystallization Compaction Cementation

Moraine-

A deposit of till left behind by a retreating glacier.

What are Destructive Forces?

A destructive force is a force that breaks down or pulls apart rock Examples: Weathering Erosion Melting

A glacier-

A large mass of ice that moves over land. • A glacier forms where there is more snow fall then snow melt each year. The excess snow becomes packed together and forms the glacier.

Loess-

A mound ofdustthat has been built up over time by wind in a location far from a desert or a beach • Loess is a valuable resource because overtime it forms good soil for growing crops.

Dune-

A mound ofsand in a desert or on a beachthat is built up by wind. • Although wind is a less powerful force of erosion than water, in areas that are dry and have no plants to hold the soil in place, wind can still move and deposit sediment.

Divide-

A ridge(elevated land) from which water drains to one side or the other. • Divides can run along high mountains or if on flatter ground divides can simply be the highest line of land.

TYPES OF GLACIERS

Alpine Glaciers-form in mountains and flow down through valleys. • Continental Glaciers(also know as "ice sheets") - much larger, flatter glaciers that can cover whole continents.

Which of the four locations would be best place to build a house? Which of the four locations would be the worst place to build a house? Explain the reasoning behind your selections. Additionally, state which mass wasting event would most likely occur and which would least likely occur. Support your selections.

Best: B - it is far enough away that any mass wasting event should not affect the house Worst: C or A - any mass wasting would cause tremendous damage to the home. Rockfall would be the most likely mass wasting event due to the steepness of the hill. A creep would not occur because they only occur when there is a gradual drop in elevation Event occurring: Rock Fall Event not occurring: Slump, mudslide, or creep

What is the primary cause of the creation of caverns and sinkholes? a. Chemical weathering b. Deposition of sediments c. Lava cooling d. Mass wasting. Provide support to your answer:

Chemical Weathering- The slightly acidic groundwater chemically reacts with the limestone in the ground and creates a cavern which eventually can become a sinkhole if the water drains out of the cavern and the overlying ground gives away.

Which of the following is not a landform produced by longshore drift or longshore currents? a) Sandbars b) Barrier Islands c) Coral Reefs

Coral Reefs

Oxbow Lakes-

Crescent shaped lakes that are formed when there is a flood and a stream cuts a new channel. The new channel bypasses a meander. The original meander is now cut off from the water source. The result is the formation of a crescent-shaped lake.

Alluvial fans-

Deposited at the base of a mountain. • They form where a stream leaves a steep valley and enters a flatter plain. When the ground flattens the water flow slows. This allows the heavier sediments to be deposited.

Barrier Islands-

Form from strong longshore currents that mostly move in one direction. These currents cause sandbars to build up over time until islands are formed. • These islands get the name "barrier island" because they protect the main coast from severe weather. • Barrier islands are constantly changing shape based on the current erosion.

Sinkholes-

Form when the water inside a cavern empties. As a result,the roof of the cavern collapses due to the lack of support.

A process happens to rocks beneath the earth's surface. Due to movements in the crust, rocks are frequently pulled under the surface of the earth, where temperatures increase dramatically the farther they descend. Between 100 and 200 kilometers (62 and 124 miles) below the earth's surface, temperatures are hot enough to melt most rocks. However, before the melting point is reached, a rock can undergo fundamental changes while in a solid state — morphing from one type to another without melting.

Heat and Pressure

Examples of this rock type include basalt and obsidian.

Igneous

Igneous

Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava). When lava cools very quickly, no crystals form and the rock looks shiny and glasslike. Sometimes gas bubbles are trapped in the rock during the cooling process, leaving tiny holes and spaces in the rock.

Examples of this rock type include gneiss and marble.

Metamorphic

Metamorphic

Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface.

Examples of this rock type include conglomerate and limestone.

Sedimentary

Sedimentary

Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock. Generally, sedimentary rock is fairly soft and may break apart or crumble easily. You can often see sand, pebbles, or stones in the rock, and it is usually the only type that contains fossils.

The water in the Nile River flows from Lake Victoria to the Mediterranean Sea. Lake Victoria is south of the Mediterranean Sea. Thus the Nile's water flow is from the south to the north. There's a common misconception that rivers should flow from the north to the south. Which of the follow statements best describes the reason why the path that the Nile's water flows is the south to north? a) The Egyptians built a system of aqueducts from Lake Victoria to the Mediterranean Sea that has allowed the water to flow that direction b) Due to the swirling currents of the Mediterranean Sea water is pulled from Lake Victoria toward the sea. c) Lake Victoria water is more dense than the Mediterranean Sea's water causing the water to flow from most dense to least dense d) The Nile's water originates from Lake Victoria which located at a higher elevation then the Mediterranean

The Nile's water originates from Lake Victoria which located at a higher elevation then the Mediterranean

Drainage basin-

The area of land in which water drains into a stream system • In most drainage basins, the water eventually drains into a lake or an ocean. Example: The Mississippi River drainage basin allows water to flow into the Gulf of Mexico

Floodplain-

The area of land on either side of a stream that is underwater every time the stream floods. • Floodplains often have very fertile land that supports lots of plant growth due in part to the sediment that is deposited when the stream floods.

Deltas-

The build-up of sediments at the mouth of a river. • When a river enters an ocean the river water slows down allowing for the deposition of larger sediments

Miley goes on vacation to Seattle with her family every summer. Upon arriving, she was informed that a rockslide had just occurred in a nearby mountain range. Later on that week, she heard that a creep occurred in the same mountain range. Miley was familiar with both mass wasting events and was perplexed that both events occurred in the same mountain range. Which event did not likely occur? Please provide support for your answer.

The creep likely did not occur due to the slope of the mountain range. Creeps are less drastic mass wasting events that occur over a long period of time in less elevated areas.

Meanders -

The curves and bends of rivers. • Rivers curve and bend because moving water erodes the outside bank and deposits sediment along the inside bank.

• Longshore current-

The movement of water along the shore as the waves strike the coast at an angle. • Longshorecurrents change daily, as the wave direction changes daily

Sandbars-

The ridges that build up along shorelines through the action of waves depositing sand. A sandbar that has built up above the water's surface and is joined by land is know as aspit.

Till-

The sediment that is picked up and then deposited on the ground when a glacier retreats.

Longshore drift-

The zigzag movement of sand traveling along a beach. • Wind blowing waves far from shore causes the waves to hit the beach at an angle. The angled waves carry sand up onto the shore and then recede back into the ocean creating the zigzag shape.

Facts about about loess?

They form in a desert They are made from dust Wind is the driving force behind their formation They develop into fertile soil

What if the magma doesn't erupt out of a volcano, but instead gets pushed slowly upward toward the earth's surface over hundreds, thousands, or even millions of years?

This magma will also cool, but at a much slower rate than lava erupting from a volcano. The kind of rock formed in this way is called intrusive igneous rock. It intrudes, or pushes, into the earth's interior and cools beneath the surface.

Which of the following would not be considered a trigger to initiate (start) a mass wasting event? a. Slope b. Earthquake c. Rain d. Trees

Trees

Pebbles, the rock, complains about his view all day and all night. He is cemented together with many other rocks at the top of a mountain. He wants to change his location badly but doesn't know where to begin. Which of the following would be the first step in allowing Pebbles to achieve his goal? a. Deposition b. Mass wasting c. Drainage d. Weathering

Weathering

Weathering & Erosion

What do dandelions rely on to separate their seeds, carry them, and deposit them elsewhere? The wind. All objects on the earth's surface are exposed to the wind, along with many other elements — water, the sun, temperature changes. Over time, these factors wear objects down and break them apart. The resulting bits and pieces of material are called sediment. Sediment is then transported by wind and water, often ending up far from where it started. These processes of breakdown and transport due to exposure to the environment are called weathering and erosion. Weathering and erosion affect all rocks on the earth's surface.

Melting

What happens to a chocolate bar when it gets very hot? It melts. The same thing happens to a rock when it is heated enough. Of course, it takes a lot of heat to melt a rock. The high temperatures required are generally found only deep within the earth. The rock is pulled down by movements in the earth's crust and gets hotter and hotter as it goes deeper. It takes temperatures between 600 and 1,300 degrees Celsius (1,100 and 2,400 degrees Fahrenheit) to melt a rock, turning it into a substance called magma (molten rock).

Compacting & Cementing

What happens to a loose pile of garbage when it's put into a compactor? The squeezing of the machine produces a solid cube of compacted garbage. The same thing happens to sediment formed from the weathering and erosion of rock. Over time, sediment accumulates in oceans, lakes, and valleys, eventually building up in layers and weighing down the material underneath. This weight presses the sediment particles together, compacting them. Water passing through the spaces in between the particles helps to cement them together even more. This process of compacting and cementing sediment forms sedimentary rock.

Cooling

What would you do to turn a melted chocolate bar back into a solid? You'd cool it by putting it into the refrigerator until it hardens. Similarly, liquid magma also turns into a solid — a rock — when it is cooled. Any rock that forms from the cooling of magma is an igneous rock. Magma that cools quickly forms one kind of igneous rock, and magma that cools slowly forms another kind. When magma rises from deep within the earth and explodes out of a volcano, it is called lava, and it cools quickly on the surface. Rock formed in this way is called extrusive igneous rock. It is extruded, or pushed, out of the earth's interior and cools outside of or very near the earth's surface.

A dune is a sand mound built up primarily by: a) Water erosion b) Glacier erosion c) Wind erosion

Wind Erosion

Topographic map-

a map used to measure the elevation of the land. • The map uses contour lines to show areas of equal elevation. • When the lines are closer together, the sloping is steeper.

The name of the sediment deposited by glaciers is called?

a) Till b) Moraine

What is statement is not true about an alpine glacier? a) Alpine glaciers can be found in top of mountain peaks b) Alpine glacier's movement is based on gravity c) Alpine glaciers pick up sediments and deposit the sediment downhill d) Alpine glaciers can cover whole continents

d) Alpine glaciers can cover whole continents

The _____________ main types, or classes, of rock are sedimentary, metamorphic, and igneous and the differences among them have to do with how they are formed.

three

Glacier Movement

• Gravity causes the glacier to move downhill. The process is calledSliding: When melted water from the glacier forms a slippery barrier for the glacier to slide on like a slip-n-slide. The water reduces the friction between the glacier and the Earth's surface As a glacier moves, it breaks up rock and pushes and carries Sediment

What is mass wasting and what role does gravity play in mass wasting?

• Mass wasting- the downhill movement of rocks and soil. • Gravity pulls the material downhill at various rates of speed\ • Common triggers for mass wasting include: heavy rain and earthquakes. These events loosen soil and the loosened soil gives way to gravity.

What is the water table?

• Not all rain water flows into surface bodies of water, some soaks into the ground. • At certain depths below the surface, the space in soil and rock becomes completely saturated with water. • The top of this water-filled region is called the water table. The water below the water table is called groundwater.

Types of mass wasting

• Rockfall- individual blocks of rock drop suddenly and fall freely down a cliff or steep mountain Rockslide- a large mass of rock slides as a unit down a slope Mudflow- when debris slides downhill with a large amount of water in it. Slump- are less dramatic slow moving slides of debris that move in a single unit. Creep- the slowest form of mass movement. They only move a few millimeters a year - a movement so slow that it can't be seen

Often times the terms weathering and erosion get misused, so what is the deference between the two?

• Weathering = the act of breaking a rock down • Erosion = the transportation of the broken pieces of rock Examples: Hail clipping chunks of rock off a hill = weathering Mr.Hardymoncarving a stone statue of Mr.Arend= weathering A stream moving small pieces of rock downstream = Erosion Sand being blown in the wind when you shake out a beach towel = Erosion

Geographic features caused by underground water movements

• When slightly acidic groundwater comes in contact with certain sedimentary rocks (limestone) that groundwater chemically weathers the rock. • Overtime large spaces develop and form caverns. • If the water table drops these caverns become filled with air.