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Soil Creep
The most important mass-movement type in terms of transferring material downhill is soil creep, the slow (typically inches, or centimeters, per year or less) downslope motion of soil. Creep may be just a very slow landslide. It may occur from freeze-thaw processes—a column of ice that grows under a small pebble on a cold night pushes that pebble out from the hillslope, and the pebble falls straight down when the ice melts, effectively moving a tiny distance down the hill (see the video above). When trees fall over and uproot soil, or when groundhogs and even worms dig up rock grains and allow them to move downhill, creep is occurring. If you look at a typical hill slope, streams on the lower slopes are present to move water and rock downhill, but the upper slopes lack streams. There, soil creep moves the material downhill.
Naturally, hillslopes typically reach a balance, in which weathering breaks down rocks about as rapidly as mass movement and streams take the broken rocks away. The balance may occur with bare rock sticking out (making cliffs, for example), or with a lot of soil covering the rock. If soil creep dominates the mass movement, the hillslope may be close to balance at all times. If landslides dominate, then the soil will build up for a while before suddenly sliding off, and you have to watch for a long time to see the balance. Over a very long time, the hill will usually get flatter, causing the mass movement to slow. However, the soil will very gradually thicken to slow the weathering as the hillslope is reduced, and near-balance will be maintained.
Humans are greatly upsetting this balance worldwide. Our activities—bulldozing, cutting trees whose roots held the soil, plowing, and more—are moving more material than nature moved before we were involved. Landslides are becoming more common, and causing more damage as we build in more dangerous areas. Soil erosion has increased from our farm fields, making it harder for us to feed ourselves.We could slow or reverse many of these damaging trends if we decided to work at it.
Video: Soil Creep/Frost Heave (1:59)
Click here for a transcript of the Frost Heave video.
There are many processes that move soil and loose rocks slowly downhills as soil creep. One of them we're going to show you here. We've drawn for you a hill with a pebble, just a little piece of rock, less than a half an inch or so. There would be lots of pebbles on this hill. Now sometimes on a cold night, ice will grow beneath the pebble and it will push it away from the hill as is shown here. This is a picture of how that process looks in the real world. So this is ice and it has shoved these pebbles up by about one inch from a little hillside. These are pine needles and these are pieces of leaves and bark. So, you can see this is at Colyer Lake in Central Pennsylvania. Now what will happen next is that the ice will melt during a warm day and when the ice melts the pebble will tend to fall down. And the net from that will be that the pebble has moved a little bit down the hill in a day or so. Later in the semester we will see that this process also happens to bring rocks out of the soil, up to the surface, so they can then be moved downhill. Pennsylvania's hillsides had a lot of this process during the Ice Age when we were in a permafrost climate. And our hillsides now are covered with big rocks that will twist your ankle if you're hiking if you're not careful and this is part of soil creep.
Credit: R. B. Alley © Penn State is licensed under CC BY-NC-SA 4.0
Here is a simplistic diagram. See if you can describe what is happening to a friend and then take a look at some truly amazing landslides from around the globe.
A Slideshow of Landslides Around the Globe
Optional Enrichment
These will not be on the quiz but might prove interesting. First, let's start with a video of some amazing landslides.
Video: Top 5 Massive landslide Caught on Camera (10:40)
Click here for a transcript of the Top-5 Massive landslides Caught on Camera video.
You can hear background noise, but no true conversation.
Credit: The Royal TV. YouTube. February 26, 2019.
And now a retro video about one of the National Park's most iconic elements.
Video: Formation of Delicate Arch (2:40)
Click here for the transcript of the Formation of Delicate Arch video.
Here we are at Delicate Arch. With the possible exception of Old Faithful, this is the most famous feature, the symbol of the parks. This is one of the very many, more than 2,000 arches, that are in Arches National Park, and it shares with them the same origin. These are not carved by running water shooting underneath them. Nor are they carved by wind blasting a hole through it. They're carved mostly by some very odd processes.
Down below, there's a layer of salt that was deposited in a sea a long time ago that was drying up here. Salt, when it's down deep and there's something sitting on top of it, is soft, and it flows. And the salt has flowed into sort of a mound, something like a lava lamp bulging up, and that mound has warped the rocks. And if you take rocks and sort of warp them up, they crack. And so there are these cracks that have made standing vertical walls of rock.
Well, the next thing that happens, if we look at that running along towards the bottom, there's a line on both sides of it. That's a soft layer, and it weakens things. Well, when you start undercutting a cliff-- we have these cliffs, and they get undercut by water leaking out along these little cracks-- then what happens is pieces fall off. And enough pieces fall off that eventually one of the pieces breaks through, and then it's an arch.
This arch is not long for the world. We see on the left, about halfway up, how thin it's getting. And we also see at the top a whole bunch of cracks that are developing. That layer across the top is trying to sag, and as it does, there are cracks that are forming. And some of those cracks sort of look like Pennsylvania keystone sitting up there.
And so it might last thousands of years. It might go in the next big storm. But it is not terribly long for the world. We know that many of the prominent and famous features in the park have changed in the time people have been watching. It will be a loss, but an educational one, when this very famous feature of the Park Service also changes.
Credit: R. B. Alley © Penn State is licensed under CC BY-NC-SA 4.0
Soil Erosion
(An extensive collection of animations on this subject)
Mass Wasting/Landslide Animations
(An extensive collection of animations on this subject)
‹ Mass Movement up A Rocking Review: Somewhere Over the Puddle ›
FAQs
What are the 5 causes of soil creep? ›
Soil creep is determined and modified by climate (temperature and soil moisture conditions), biota, topography, rock weathering processes, and soil production rates [6, 26].
What are the three types of soil creep? ›This is the slow movement of soil materials down slopes under the influence of gravity. The soil is normally lubricated by a good deal of moisture or aided by frost heaving (q.v.). Four kinds of creep were identified by Sharpe (1938): soil creep, talus creep , rock-glacier creep , and rock creep.
What is a famous example of soil creep? ›One example of soil creep in real life is from the wealthy Caribbean nation of Trinidad and Tabogo. In this country, in 2012, expensive road repair plans (estimated at about 61 million dollars!) were announced. The area surrounding the road which needed repairs was subject to soil creep.
What is the soil creep? ›Soil creep defines the slow mass wasting process of soil on a slope, under the influence of gravity (Source: Glossary of Soil Science terms, Soil Science Society of America).
What are 3 signs of soil creep? ›Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges.
How do you stop soil creep? ›Proper drainage can remove groundwater from the area, increasing resistance to soil creep. Install drainage features, and replace failed soil with properly compacted fill or recompact in situ material. Use adequate groundcover to prevent erosion in slopes with sand.
Where is soil creep most common? ›Soil Creep
It is most common in damp soils where water acts as a lubricant. This allows soil particles to move over each other and the underlying rock. Eventually, the movement of soil tilts fences, posts and even trees.
They can occur after periods of heavy rain, when the water saturates overlying rock, making it heavy and liable to slide. Soil creep is a very slow movement, occurring on very gentle slopes because of the way soil particles repeatedly expand and contract in wet and dry periods.
What are two factors affecting soil creep? ›The results of graphical and statistical analysis showed that rates of creep are controlled by a number of 'force' factors, chiefly soil moisture, field capacity and plasticity index, together with 'resistance' factors, particularly bulk density and a number of shear stress measures.
What is creep most often caused by? ›At elevated temperatures and stresses, much less than the high-temperature yield stress, metals undergo permanent plastic deformation called creep.
How do you stop slope creep? ›
The two most common forms of slope creep mitigation are retaining walls (to intercept the slope) and steel pier underpinning (to secure and stabilize homes and decks against lateral movement).
Can soil creep be detected? ›Creep soil landslides are usually characterised by loosely defined limits, which makes them difficult to detect. If countermeasures are not taken, constructions and infrastructure built on these landslides can suffer damage over time.
What is another word for soil creep? ›Downhill creep, also known as soil creep or commonly just creep, is a type of creep characterized by the slow, downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress.
Is soil creep a natural hazard? ›Creep, being a deformation occurring at rather low rate, is rarely hazardous, although it may result in weakening of building foundations and tilting of trees and other vertical man-made structures (e.g., poles, masonry walls, gravestones) in the longer term, the latter leading to their collapse.
What is the difference between soil creep and soil flow? ›Flow: occurs when material moves downslope as a viscous fluid. Slump: similar to sliding movement, but the descending material moves along a curved (circular) surface of rupture. Creep is the slow downslope flow of soil and loose rock fragments.
How do you identify soil creep? ›Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges.
How often does soil creep occur? ›Creep is the imperceptibly slow, downslope movement of soil and earth materials. Rates of movement are often only a few centimeters per year, but the inevitability of creep can severely impact shallowly-placed structures.
Why is soil creep bad? ›A study out of Japan found that soil creep helps build up soil in places where landslides could occur. As more and more soil builds up at these points, the more tension there is. These points of tension eventually release, causing debris flows and landslides.
How much does soil creep move in a year? ›Creep is ground movement of roughly one centimeter/year or less. It is generally only possible to observe creep over many years. Usually the tilting of trees and human structures are the best indicators of creep. Freeze-thaw cycles generally aid creep, as well as occasional water saturation.
What factors facilitate soil creep? ›Soil creep has been traditionally considered as a set of slow movements (continuous and seasonal), caused by climate (temperature and moisture conditions) and biota, and balanced by topography, bedrock weathering processes and rates of soil production (Terzaghi, 1950; Kirkby, 1967, Kirkby, 2004; Heimsath et al., 2002; ...
What can facilitate soil creep? ›
Creep can be facilitated by freezing and thawing because, as shown in Figure 15.12, particles are lifted perpendicular to the surface by the growth of ice crystals within the soil, and then let down vertically by gravity when the ice melts. The same effect can be produced by frequent wetting and drying of the soil.
What is the difference between a soil creep and a rock slump? ›What's the difference between a creep and a slump? Creeps and slumps are very similar. They are both a form of mass wasting and have the same causes. The difference between a creep and a slump is that a creep moves slowly and gradually while a slump is faster and causes more drastic changes in terrain.
What are four indicators of occurrence of soil creep in an area? ›- Telephone/fence poles that are inclined down a slope/bent tree trunks.
- Accumulated soil at the foot of a sloop/behind obstacles such as walls.
- Existence of bare rock/exposed upper slope.
- Presence of a ribbed/stepped pattern across the slope.
Scraping of the forest floor leads to destruction of the top layer of soil that is rich in humus and decreases soil fertility. Thus, it will lead to soil erosion by wind and water.
Is soil creep faster than sloping? ›Soil creep is faster than slumping. Landslides only occur in inclined areas. Depressions on the ground that resulted from the collapse of the surface layer of the soil is called a sinkhole. Rock fall landslides are made of water saturated soil.
What are the four types of creep? ›The four types of scope creep in project management
Scope creep fits into four distinct buckets: business creep, effort creep, hope creep, and feature creep.
Indicators of creep include tilting and separation of walls in a down slope direction, tension cracks near the top of a slope, and curved trunks of trees which have been growing on a creeping slope for many years.
At what temperature does creep occur? ›The point, then, is that the temperature at which materials start to creep depends on their melting point. As a general rule, it is found that creep starts when T > 0.3 to 0.4 Tm for metals and alloys, T > 0.4 to 0.5 Tm for ceramics.
What are 4 methods of controlling soil erosion? ›- Maintaining a healthy, perennial plant cover.
- Mulching.
- Planting a cover crop – such as winter rye in vegetable gardens. ...
- Placing crushed stone, wood chips, and other similar materials in heavily used areas where vegetation is hard to establish and maintain.
Create flat spaces with retaining walls
Carving out part of the slope and adding a retaining wall to hold back the soil will allow you to create a flat area in your backyard. These can create planting areas, seating areas, or recreational areas for the family.
What gravel is best for erosion control? ›
To be used as soil erosion control, the gravel needs to be hewn from natural stone that is porous such as sandstone because this allows water to soak through the tiny capillaries within the rock and get to the soil.
What are the warning signs of soil creep landslide? ›Unusual sounds, such as trees cracking or boulders knocking together, might indicate moving debris. Collapsed pavement, mud, fallen rocks, and other indications of possible debris flow can be seen when driving (embankments along roadsides are particularly susceptible to landslides).
Is soil creep a landslide or sinkhole? ›The slowest kind of landslide is known as creep. When clay in the soil on a hillside absorbs water, it will expand, causing the soil to swell. As the clay dries and contracts, the particles settle slightly in the downhill direction.
What is the speed of soil creep? ›Creep is a type of mass movement; it is the slow, downhill movement of rock or soil under the influence of gravity. In a creeping slope, the creeping top layer typically moves at rates ranging from half a centimeter to as much as 10 cm per year.
What does it mean to be on all fours? ›(of a person) on the hands and feet, or the hands and knees: I had to go on all fours to squeeze through the low opening.
What is one main cause of creep? ›It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material. Creep is more severe in materials that are subjected to heat for long periods and generally increases as they near their melting point.
What are the five 5 factors that affect soil development? ›Scientists attribute soil formation to the following factors: Parent material, climate, biota (organisms), topography and time.
What are the signs of creep? ›- Stands too close to you/others.
- Has greasy or unkempt hair.
- Has a peculiar smile.
- Has bulging eyes.
- Has long fingers.
- Has very pale skin.
- Has bags under his or her eyes.
- Wears dirty clothes or dresses oddly.
Primary Creep: starts at a rapid rate and slows with time. Secondary Creep: has a relatively uniform rate. Tertiary Creep: has an accelerated creep rate and terminates when the material breaks or ruptures.
Is creep caused by gravity? ›Creep may appear to an observer to be continuous, but it really is the sum of numerous minute, discrete movements of slope material caused by the force of gravity.
What is being done to stop soil degradation? ›
Here are some solutions: Practicing crop rotation allows different plants to grow in an area of soil every year. This allows the soil to replenish itself of nutrients that are lacking after the growth of one type of plant. Agroforestry involves growing crops around trees and other plants such as hedges.
How do you determine soil order? ›Soil orders are frequently defined by a single dominant characteristic affecting soils in that location, e.g., the prevalent vegetation (Alfisols, Mollisols), the type of parent material (Andisols, Vertisols), or the climate variables such as lack of precipitation (Aridisols) or the presence of permafrost (Gelisols).
What is the most important factor in soil formation? ›Climate: This is probably the most important factor that can shape the formation of soils. Two important climatic components, temperature and precipitation are key. They determine how quickly weathering will be, and what kind of organic materials may be available on and inside of the soils.