Glacial Sedimentation: Composition, Grain Size Distribution, and Morphology

This article discusses glacial sedimentation, including its composition, grain size distribution, morphology, and effects of environment. It also covers the arrangement of sedimentary rocks in layers.

Running head: SEDIMENTOLOGY AND STRATIGRAPHY 1
Sedimentology and stratigraphy
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SEDIMENTOLOGY AND STRATIGRAPHY 2
Glacial sedimentation
Glacial sediment can be defined as the materials entrained by moving ice of glacier deriving from erosion.
Glacier is a dense mass of moving ice or snow under its own weight. Therefor glacial sediments are simply the material
found within these masses of moving ice.
Glacial sediment composition
As the glacier moves on the surface, it picks up masses of sediments on the ground surface. Some of these
sediments include rocks, soil, debris, and sand. These picked up particles get stuck in the moving ice and travel along
with it even for very long distances. They can later be deposited in different locations. When these materials are
deposited in unsorted form, they form terminal, lateral, medial and ground moraine. When these components of the
glacier are sorted they are termed to as outwash while the unsorted ones are called drift.
Clastic and chemical sediments
Clastic sediments are those glacial sediments that consist of broken particles of preexisting rocks and are
transported via the glacier, then deposited to form another rock. Mainly they are formed from the mechanical
weathering of debris. These sediments are known to form rocks like sandstone, siltstone, and shale. On the other hand,
chemical sediments are those particles of sediments within the glacier that are formed as a result of chemical reaction
between already existing materials or sediments in the moving glacier. Many samples collected across study areas
concerning glaciation show that these sediments contain the mineral. They are mostly clay minerals e.g., biotite, mica,
chlorite and k feldspar. (kukal, 1970) Moreover, quartz is also a mineral found in clastic sediments. After their formation
through a chemical reaction, they are deposited and in most cases form chemically formed sedimentary rocks. They
include iron ore, chert, and flint. Majorly they form from precipitation of dissolved glacier sediments. (Bennett, 2018)
Grain size distribution
In the process of glaciation and the movement of the glaciers, fragments of the sediments in the glacier occur.
Mechanical activities like crushing and chemical reactions result in different sizes of sediments. Some sediment retains
their initial grain size while others crack and disintegrate to smaller grain sizes. From many experiments, it’s indicated
that most sand sizes glacier material result from mechanical activities while silt-sized grain material results from
abrasion. Grains size distribution can be sorted In terms of; fine sand size, very fine sand, coarse silt, medium silt, sine
silt, very fine silt and clay. Majorly, in a glacier, coarse and medium-size silt grains dominate the glacier in many cases.
(fenn & Gomez, 1984)
Morphology, color, sorting, cement, porosity and cement composition of grains
The physical and chemical processes in glaciation in a greater way determine the shapes and patterns of the
clastic particles. The type of rock, the rapid changes in the glacier motion and the shifts in subglacial drainage systems
affect the size range, relief, and morphological rated features. The morphology of quartz mineral and other available
grain sized sediments in glaciers is angular and subrounded outlines and this is a direct reflection that areas undergo
dominant glacial actions. The shape is a result of mechanical actions like crushing and abrasion. (kuenen & perdok, 1962)
On the other hand, the color of the glacial water is iridescent blue-green due to the small material in the glacier and
suspended meltwater which may appear cloudy. Sorting is defined as the distribution of grain size sediments in a
glacier. When it comes to sorts, glacier sediments appear scratched and grooved and therefore in many cases are
deposited in unsorted piles. Sorting depends on the particle size, the density, the shape and the settling rate and time.
According to (shrivastava, 2014) glacial sediments are characterized by poor sorting and variable mean size particle.
Porosity is the ability to hold water. In glacier sediments, the level of porosity depends on the original rock or source of
the sediments within the glacier. (Kolla, 1987)

SEDIMENTOLOGY AND STRATIGRAPHY 3
Environment
This is the effects of surrounding on a glacier. Human activities and weather have an impact on the glacier
sedimentation. Human activities like deforestation can lead to erosion which eventually affects sedimentation.
Stratigraphy
The rocks and material resulting from glacier sediments are arranged in layers when being deposited. Some of
these layers show evidence of sand, silt, and clay as the sediments that were being carried by the glacier. In most cases,
they form sedimentary rocks which are widely known for layers. (Krumbein, 1990)
Geometry and texture
The geometry of glacier sediments includes its thickness and how its flows steeply. It’s affected by mass balance
and all dynamics. Therefore, increasing ice thickness and decreasing water depth causes deeper penetration. Glacial
sediments have a stratified texture.

SEDIMENTOLOGY AND STRATIGRAPHY 4
Reference
Bennett, s. (2018). glaciers and features of sedimentary rocks. geoscience news and information, 4.
fenn, C. R., & Gomez, B. (1984). particle size analysis of sediments suspended in a glacial stream. In C. R. Fenn, hydrogel
process (p. 123). switzerland.
Kolla, V. (1987). Morphology, internal structure, seismic stratigraphy, and sedimentation of Indus Fan. AAPG Bulletin,
650-677.
Krumbein, W. C., & Sloss, L. L. (1951). Stratigraphy and sedimentation (Vol. 71, No. 5, p. 401). LWW.
kuenen, P. H., & perdok, W. G. (1962). Experimental abrasion 5; frosting and defrosting of quartz grains. glacial
sediments, 648-649.
kukal, Z. (1970). Geology . In geology of sediments (p. 490). prague academia.
Nichols, G. (2002). Sedimentology and Stratigraphy. A John Wiley and sons publication.
Srivastava, p. K. (2014). The sediment properties of glacial diamicts from the Jutulsessen area of Gjelsvikfjella, East
Antarctica: A reflection of source materials and regional climate. Polar science , 264-282.