the characteristics of the till plain and it's associated features

Glacier not only performs erosive and transportational activity but also depositional activity.

   Till is a type of a sediment in which the components have been brought into contact by direct agency og the glacier ice. Inspite of the subsequent glacially induced flow  it does'nt become disaggregated.It's a glacial deposit.there has been little or no sorting by water.

      The most widespread evience of the subglacial action is the formation of rolling,low relief till plain,covering vast areas and are indicative of the non-landforming -thrust block ridges,depression and push ridges can be found which reflect localised subglacial differential stress,local variations in sediment rheology or influence of topographic control.they have formed due to uniformity of sunglacial depositional conditions.however,they do not signify till type uniformity.It's sediments are complex reflections of the local and regional bed geology,topography,ice dynamics and subglacial bed conditions.Other features like-lodgement,meltout,flow tills and melanges are found over large or estricted areas of the till plains.these plains contain rafted units of the subjacent  sediments and bedrocks.

The associated features of the till plain are as follows:-

A)End moraines:-They are ridges accumulating  along and at margins of glaciers.It's a ice marginal glacial form. They partially reflect bedrock topography,earlier glacial event or multiple depositional episodes.

1)Superposed end moraines:-Those composed of deposits from the two or more glacial advances.

2)Rock-cored end moraines:-Those occurring over bedrock highs.

3)Palimpsest end moraines :-Those that are buried by the thin drift cover of the glacial event.

they vary in morphology and sediment content. Those related to the ice sheet and ice caps are commonly articulate in outline,while some are short or composed of discontinuous ridges.Many end moraines are composed of diamictions  and are sorted sediment that originated in supraglacial environments through subglacial till may also occur commonly followed by debris flow deposit na d sorted fluvial and lacustrine sediments.

Push moraines  are end moraines of glaciotectonic origin composed primarily of large thrust masses of sediment and bedrock,often imbricated that have been derived from beneath the glacier.Example:-pleistocene push moraines of the Dammer Berge, Germany.

B)Ground moraines:-

They are those moraines which lack the conspicuous ridge like form. If thick, it’s topographical expressions is a till plain. Clay tills give rise to flat till plains or undulating surface which are called swell and swale topography.

1)Veiki moraines:-They appear like near circular plateau surrounded by a single or double rim/ridge.Mechanisms of it's formation are subdivided into:-subglacial origins under the passive/active ice;and supraglacial origins.

2)Hummocky moraines:- they are chaotic steep sided piles of dominantly subglacial debris that lack a coherent directional pattern and are often associated with the marginal areas of the ice masses and has  an active ice margins. Example:-Rannoch Moor,Scotland.

3)Pulju moraines:-

It comprises of chaotic ridges which are winding and hummocky. Their origin is problematic and is probably formed due to squeezing up of sediments in the crevasses or due to general ice disintegration during deglaciation or due to lateral pressure induced redging,both under passive ice condition preferentially within 200 Km. of the ice divide.

c)Drumlins:-

They are roughly ovoid shaped hills of dominantly glacial debris that typically occur within groups or fields of several thousands. They exhibit very strong enecholon long axis preferred orientation paralleling the main direction of the ice flow. The classical shaped drumlins has a steeper cross end and tapered leeside limited relationship occur between drumlins and topography.they are composed of vast range of sediment types although previously it was thought to be exclusively formed of the subglacial till and may reflect past depositional subaerial mass movement.

D)Lodgment tills:-

As ice comes in contact with it's bed and frictional heating occurs causing ice scoured ebis to be released into the contact zone between the ice and the bed a process of regeleation.They form widespread continuous till plains often with the bed forms like-drumlins,rogen moraine and fluted moraines.

E)Meltout tills:-

They are formed as a result of the massive in situ melting and subsequent deposition from supraglacial and lower(subglacial) englacial zones of an ice mass.They are relatively thin, coarse grained,occuring as spatially disjunctive patches within the features:-

1)Presence of stratified units,

2)Faults,fractures and slump structures and

3)englacially inherited structures.

F)Floe tills:-

It contains clasts from many sources which exhibit strong, unidirectional orientation. The structures associated exhibit wide range of folds,faults,riedel shears and kink band arrays.