Scales of Change on Earth's Surface

Example of catastrophic event - flash flood

A flash flood happens without warner and lasts for only a few hours. Flash floods are caused by heavy rainfall over a very short period of time.

Hoodos

Although hoodos occur in different locations and are made of different types of rock, they are all formed the same way. That is why they look so similar. These formations provide evidence that the same natural processes in this case - weathering and erosion act the same way everywhere on Earth. Water, wind, and gravity break down rocks into smaller and smaller pieces and transport them to new locations. These processes shape and change earth's surface.

Example of catastrophic event -astroid collision

An asteroid is a large mountain size chunk of rock that is in orbit around the sun. It might be in orbit around the sun for billions of years before colliding with Earth. An astroid collision is a powerful force, like the explosion of a bomb. On impact, it creates a huge crater on the earth's surface. The impact ejects a large amount of dust into the atmosphere - enough to block sunlight. The decrease in sunlight causes a global decrease in temperature that can last from several days to several years.

Changes to mountinous landscapes

Been happening for a million years

Rocks in Southern Utah

Called Hoodos occur in a number of places around the world. A hoodo is a pillar of rock ranging from about 1.5 meters to 45 meters tall, usually with a rock cap at the top. Hoodos all have the same shape.

Changes to Earth's Surface

Can occur on a small or large scale. Small scale changes can be caused by living organisms, wind, water, ice , gravity and chemical reactions

Slow and Fast Changes On Earth's Surface

Earth processes occur on a timescale ranging from microseconds to billions of years. Some processes such as weathering and erosion, can change the landscape gradually (slowly) over long periods of time. Examples are catasrophic events like volcanic eruptions and flash floods can change Earth's landscape suddenly and rapidly. Even though catasrophic events occur quickly, the conditions that lead up to them can take a long time to develop.

Changes that happen slowing

Earth processes operate on all scales of time, from billions of years to a fraction of a second. Example of gradual ( slow) process that changes Earth's surfaces include: movement of the continents, uplift, weathering, erosion and deposition.

Earth's Surface Gradual (slow) Changes

Earth's surface is constantly changing. Some changes occur very slowly. Gradual processes that change Earth's surface include the movement of continents, uplift, weathering, erosion and deposition.

Catastrophic Events

Even though these events are short lived, they often have a big impact on Earth's surface.

Patterns of Change

Features on Earth's surface may appear to be stable because the changes that are happening are too small and too slow to notice. Many small, slow changes, add up to big changes over time. Those changes are caused by Earth processed that occur globally. That is why the same rock formations can be found in different locations all over the world ( think Hoodoos example). Scientists think that the processes that are happening now have always occurred on Earth and will continue to do so in the future.

Sandstone formation

Formations of a sandstone can take millions of years to form. Sand is transported by water or wind and settles in layers. Over time, more materials are deposited on top of the layers of sand. The weight of these materials causes the sand layers to become cemented together (to compact and eventually harden) into sandstone

Changes that happen fast

Gradual changes that occur from weathering, erosion, deposition and uplift can be interrupted by sudden catastrophic events. Thousands, millions or billions of years may pass between such events, but when they occur, Earth's surface can change quickly and dramatically.

Catastrophic Events - landslide

Happens very quickly like a flash flood. Landslides and flash floods happen when events like heavy rainfall and earthquakes make unstable ground move. Landslides may last only a few minutes, but the result can be devastating

Length of time for a hoodoo to form

Hoodoos can take anywhere from thousands to millions of years to form. They are still weathering and eroding, but process is too slow to notice. If you were to visit these formations today and then again in a year, they would look the same. The formations may appear stable because the changes that are happening are too small and too slow to observe in such a short period of time. However, sometimes hoodos undergo fast changes. At some point, a pillar will become so thick that it can no longer support the boulder on top, and the boulder will topple to the ground. All those small, slow changes will have added up to one big sudden change that is hard to miss because the pillars collapse.

Continents

It has taken billion of years for the continents to assume their current shape and positions. You can't feel it, but the continents are still moving and changing shape - at a rate of one to three centimeters per year.

Cave

Most caves form when water comes into contact with limestone. A chemical reaction between the water and limestone causes the limestone to slowly dissolve into the water. Over thousands and thousand of years, this chemical weathering removes the limestone to form a cave.

How long does I take for water to break down rock or fill a lake?

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Earth Processes at Difference Scales of Time and Scales - Human Scale

On the human scale, time is measured in units ranging from seconds to years.

Erosion

Over time, rock material breaks into smaller pieces that can be moved. Erosion is the removal of rock material by wind ,water ,ice ,or gravity

Erosion

Processes by which rock, sand, and soil are broken down and carried away (i.e. weathering, glaciation)

Rock

Rock that comes in contact with water, ice, wind and organisms is broken down into smaller material and transported and deposited at different locations. These interactions whether they happen on a small scale or a large scale, result in constant changes that have shaped and will shape the Earth's surface.

Weathering, erosion, and deposition on Earth are the result of interactions between the four Earth Systems.

Rock, water, wind and organisms are all parts of these systems.

Changes on a small scale

Scientists study changes on Earth's surface at different scales to understand the processes that have shaped its features. Footprints and ripples in sand are examples of small scale changes

Many Small Changes Add up to Large Changes

Small changes can eventually lead to large changes on the Earth's Surface. Ex.

Factors that cause weathering, erosion and deposition of rock material

Small scale changes can be caused by living organisms, wind, water, ice, gravity and chemical reactions.

Volcanic Eruption - length of time

Some eruptions can last for several weeks, but they are the result of many slow changes beneath Earth's surface over a long period of time.

Namib Desert Example

Some of the largest san dunes in this desert are 240 m tall and 32 km long - among the largest on Earth. Just as sand ripples are formed by erosion and deposition, sand dunes are also formed by erosion and deposition, on a much larger scale.

Patterns of Change

Some of the most unusual rock formations on Earth can be found in Southern Utah. Nicknamed goblins by locals. These rocks look like rock bodies

Earth Processes at Difference Scales of Time and Scales - Space and Human Scale

Space and Human scale are units that humans can experience directly with their sense.

Earth Processes at Difference Scales of Time and Scales - Space

Space is measured in units ranging from millimeters to kilometers.

Changes that happen fast

Sudden events can cause fast changes to Earth's surface. Some sudden events occur with such force that their effects are catastrophic. Although these events last only a short time, the conditions that make them possible can take a long time to develop.

You live on earth's outermost layer

The Solid Crust

Weathering

The breaking down of rocks and other materials on the Earth's surface.

Weathering

The breaking down of rocks and other materials on the Earth's surface. Just as the beetle and other organisms can break down rock, so can water, ice, wind and gravity. Weathering is what caused sand to form in the first place millions of years ago.

How do Hoodos form?

They form by the processes of weathering and erosion. The rock at the bottom of a hoodoo is more resistant to weathering than the rock below, so it protects the part of the formation directly below it from being eroded so quickly.

Small and Large Changes on Earth's SUrface

Throughout its history, earth's surface has been shaped and reshaped by processes that act on different scales of size. Weathering, erosion and deposition can cause changes that range from microscopic to global in size. Many small changes can add up to large changes over time.

Earth Processes at Difference Scales of Time and Scales

To understand the world around them, scientists use scales of time and space. Earth Processes at Difference Scales of Time and Scales

Examples of events that happen fast (catastrophic event)- Volcanic Eruption

Volcanic eruption: Volcanic eruption happens when magma is forced up to Earth's surface through an opening called a vent. Once it reaches the surface, the molton rock or lava, flows over the surrounding land. This can dramatically change the landscape for many kilometers around the volcano.

What causes small changes to Big Changes

Weathering, erosion and deposition

Deposition

What happens after the rock material is removed from its original location. The rock material can be deposited in a new location. Deposition is the accumulation of eroded rock material that has been transported from another location.

Beetle Example

When the beetle steps on grains of sand, the grains grind against each other. This causes small-scale changes as the sand breaks down physically.

Namib Desert Example

Wind blown sand (88,000 km) that accumulated over the course of 55 million years. The Desert sand is still moving. This is continued weathering from people and animals walking on the sand and from wind and moving water which break down the grains even further and turn them to dust Wind carries the dust in great plumes that spread out over the Atlantic.

How solid is the crust

You will see large rocks that have broken down into smaller rocks. Over time, they break down into even smaller pieces until eventually they become grains sand light enough to be carried by the wind .

Uninformitarianism

idea that any natural process we observe today happened in the same way in the past and will also happen in the same way in the future. Scientists sum up this principle with the simple phrase - observing the present is the key to understanding the past. For example, gravity's role in weathering, erosion and deposition is the same today as it was billions of years ago and will continue that way into the future. Same is true for many other natural processes, including the influences of water and wind on rock

Changes to Earth's surface

occurs at different scales of space and time - some are microscopic and others are on a global scale. Some changes happen in a second and other take place over billions of years.

Uplift

the upward movement of large areas of Earth's crust caused by forces deep beneath the surface. Uplift can take place over the course of 100 million years and causes mountain ranges to form.