Stream deposits are usually poorly sorted because the energy (velocity) in a stream varies with position in the stream and time.
- 1 What causes poor sorting of sediments?
- 2 Where are poorly sorted sediments found?
- 3 What factors create well sorted sediments and poorly sorted sediments?
- 4 What factors determine how these sediments are sorted?
- 5 What is the most likely cause of a sediment with highly rounded grains?
- 6 Why are conglomerates poorly sorted and what does it mean to the way they are formed?
- 7 Why would a sediment become well rounded?
- 8 Which agent of erosion is responsible of well sorted sediments?
- 9 Does size affect porosity?
- 10 Which would have a higher permeability A well sorted sediment or a poorly sorted sediment?
- 11 What causes cross bedding?
- 12 What transporting agents could be responsible for the very well sorted clasts?
- 13 How do you know if a rock is poorly sorted?
- 14 How does sorting affect porosity?
- 15 Why do landslides drop large piles of sediment?
What causes poor sorting of sediments?
Ice is the poorest sorter of sediment. Glaciers can transport almost any size sediment easily, and when ice flow slows down or stops, the sediment is not deposited, due to the density of the ice. As a result, sediments deposited directly by ice when it melts are usually very poorly sorted.
Where are poorly sorted sediments found?
At the end of a glacier, where ice is melting as fast as it is being supplied from upstream, the sediments are deposited in a terminal moraine, a ridge of poorly-sorted glacial till. Thinner depostits of glacial sediments called a ground moraine or till plain are found behind the terminal moraine.
What factors create well sorted sediments and poorly sorted sediments?
The degree of sorting depends upon how much transport the sediment has undergone. Well-sorted sediments have grains of similar size, and are the result of much sediment transport and earth processes which segregated the sediment by depositing different size fractions in different places.
What factors determine how these sediments are sorted?
Geologists have also categorized sediment as well sorted and very poorly sorted. It’s the change in the speed of the agent (wind, ice, water, etc) that determines the way sediment will be sorted. Imagine what happens when fast-moving streams enter lakes.
What is the most likely cause of a sediment with highly rounded grains?
What is the most likely cause of a sediment with highly rounded grains? Longer distance transported; The longer the distance, the more the rounding.
Why are conglomerates poorly sorted and what does it mean to the way they are formed?
The poorly sorted conglomerates have a matrix of clay or sand. The abundance of unstable minerals with poor sorting indicates rapid mechanical erosion and deposition, as in alluvial fans or in density currents (i.e., highly turbid bottom currents) resulting from gravity flows.
Why would a sediment become well rounded?
“Roundness” of sediment grains: The farther a particle is moved, the more rounded and spherical it should become. Angular particles tend to be deposited close to their source, they become more rounded the farther they travel downstream. Grains of beach sand are typically well rounded.
Which agent of erosion is responsible of well sorted sediments?
Liquid water is the main agent of erosion. Gravity and mass wasting processes (see Chapter 10, Mass Wasting) move rocks and sediment to new locations. Gravity and ice, in the form of glaciers (see Chapter 14, Glaciers), move large rock fragments as well as fine sediment.
Does size affect porosity?
Because, in general, larger particles cannot pack together as tightly as smaller particles can, a rock made out of larger particles will usually be more porous than a rock made out of smaller particles. You can see how this process, known as compaction, makes the rock’s porosity decrease with time.
Which would have a higher permeability A well sorted sediment or a poorly sorted sediment?
Porosity refers to the capacity of earth materials to hold water in spaces found within and between sediments and rock. Thus, well sorted sediments have higher porosity while poorly sorted sediments have low porosity. Permeability refers to how easily water passes through sediments and rock.
What causes cross bedding?
Cross-bedding is formed by the downstream migration of bedforms such as ripples or dunes in a flowing fluid. Cross-bedding can form in any environment in which a fluid flows over a bed with mobile material. It is most common in stream deposits (consisting of sand and gravel), tidal areas, and in aeolian dunes.
What transporting agents could be responsible for the very well sorted clasts?
For Clastic rocks: Clasts (sediments) are physically transported by wind, water, glaciers, and/or gravity.
How do you know if a rock is poorly sorted?
The extent to which all the grains are the same size is known as sorting. If all the grains are the same size, they are well sorted. Some sandstones are well sorted, and some are not. Most conglomerates are poorly sorted, and consist of a mixture of grain sizes ranging from sand to pebble.
How does sorting affect porosity?
Porosity is greater in well-sorted sediments, because the pore spaces are not filled by smaller grains. Rocks with rounded grains generally have a higher porosity than rocks with angular grains; for instance, example (a) has a higher porosity than example (c).
Why do landslides drop large piles of sediment?
The more energy the water has, the larger the particle it can carry. A rushing river on a steep slope might be able to carry boulders. As this stream slows down, it no longer has the energy to carry large sediments and will drop them. Landslides drop large piles of sediment.