Dear Dr. Biswas,

the glacial environment is a very heterogeneous one as to the subfacies types and processes involved. The processes may be subdivided into true glacial deposits in moraines (ground, middle, lateral m.) and fluvial-glacial deposits (1. sub-/supra-/ englacial/ which occur in ridges, mounds e.g. esker, kames or 2. marginal or proglacial processes in small depressions sander). There are glacial lacustrine deposits mainly as spreads and terraces such as kames deltas, beach deposits at the end of the catena of facies types. Last but not least these proglacial and marginal deposits may also show up as raised marine deltas, raised beaches and mud flats.

The grain size spectrum covers the full range of particles size from gravel to clay, simply getting smaller towards the end of the process chain.

The physical differences may be described as follows: The more glacial processes prevail the poorer is the clastic sorting. By contrast a strong fluvial and marine component may improve the sorting of the clasts.

This is rough scheme of a rather complex process.

See for more details:

DILL H.G., BUZATU A., GOLDMANN S., KAUFHOLD S., and BÎRGĂOANU D. (2019) Coastal landforms of “Meso-Afro-American” and “Neo-American” landscapes in the periglacial South Atlantic Ocean: With special reference to the clast orientation, morphology, and granulometry of continental and marine sediments.- Journal of South American Earth Sciences (on-line).

Available on the RG server as a digital preprint.

Methods useful in the lab are lithoclast and heavy mineral analysis using the same sort of methods as described for the field work, excluding situmetry

mapping, mapping, mapping..... (geologically, geomoprhologically, sedimentologically)

I wish you much success

H.G.Dill

Thank you Very much Sir ..

I am going to start a study in NE Himalaya to predict the southern expansion of Mini Glacial age and their sediment entertainment considering geological, geomoprhological, sedimentological inter actions. But also searching for funds . However please keep in touch , I will send the update of the work positively.

A higher proportion of rounded to angular grains and pebbles tends to favour a fluvial environment.

Thank you Sir.

Grain size is a factor....but Erratics are also huge scale in size . So is there any other method for separating them?

I have used grain size, rounding of clasts (Krumbein method), heavy minerals clay minerals and orientation of the clasts.The latter shows direction of movement of the ice or water, while the clay minerals show weathering class (M. L. Jackson - weathering stages) if not disturbed by glaciers giving mixing of clays characteristic of the weathering sequence. Heavy minerals can show origin of the sediments while presence or absence of montmorillonite can also show whether the source was from an arid or humid area.. The lithology of the clasts can help identify origin of the sediments. Remember that the clasts get worn down with distance of travel in streams. the surface patina can help identify stones carried in glaciers, especially with limestones.

Stuart.

Ok Sir...I am going to study the sediment differentiation. Thank you...

Dear Mrs. Biswas,

the chemical component has little impact on the mode of transport and deposition since the weathering is true mechanical/ physical as it is the decisive transport parameter. Ice does not cause any density differentiation and thus neither the hydraulic nor entrainment equivalence of heavy minerals

relative to quartz can be applied to these glacial deposits. By contrast, these physical processes can well be applied to the fluvial component of the transport. In other words, the prevailance of the hydraulic differentiation and to some extent entrainment are a function of the ratio of the fluvial/aquatic (including lacustrine and marine processe) to the glacial transport mode. They should be checked and compared with the mapping of the fluvial/aquatic and glacial facies zones and landform types (see my first comment).

H.G.Dill

Glacial Till and tillite as well as diamictites can easily be differentiated by their high angularity and low roundness of grains, very poor sorting from boulders to clay, preservation of unstable minerals like feldspar and its fresh surfaces, absence of decomposed minerals, presence of striation on grain surface, lack of preferred orientation of grains etc. The glacial deposits have distinguished facies and facies association than those of fluvial. But it is little bit difficult to differentiate glaciofluvial or fluvioglacial deposits and that of fluvials. Chemically it is very difficult to distinguish them.

Thank you Sir..

In some fluvial environments you might find biological components (fauna, flora) that you won´t find in material derived or formed poorly by glaciers. But as others already mentioned there is a strong interplay beween glacier and glacio-fluvial processes depending on what scale you are looking at the related processes.

Thank you ..