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Madhupur Clay highly weathered and deeply oxidized reddish brown deposit exposed in the Madhupur, Barind and Lalmai Hill areas. Madhupur Clay represents several north-south elongated pleistocene terraces, highly dissected during the Late Pleistocene climatic episodes. Madhupur Clay makes beautiful scenery of the lalmai hills, Madhupur and Varendra areas. All the ancient civilisations, flourished at mahasthangarh [Mahasthangad], paharpur and mainamati are located in the Madhupur Clay zones. The Madhupur Clay had played a distinct role in the civil engineering works, art and culture of the ancient Bengal.
These deposits are extensively exposed in Vawal and Madhupur
Garhs of Dhaka, Mymensingh and Tangail districts. In the Barind area,
these deposits are exposed in the Greater Rajshahi and Bogra districts.
In Comilla district, Madhupur Clay capped almost all the hilltops of Lalmai
Hills. In Madhupur and Barind areas, these deposits form some north-south
elongated landmasses slightly elevated from the adjacent floodplain.
These clays are known as the Madhupur Clay Formation. The clay contains
halloysite and illite and represents relict palaeosol. Nowadays, in Madhupur
and Barind areas, this clay is called Madhupur and Barind formations respectively.
Stratigraphically Madhupur Clay has been subdivided into three members:
upper one is called Dhaka Clay Member, represented by highly weathered
deep clayey materials composed of ferruginous nodules, pipestems and manganese
spots. The middle member is called Mirpur Silty-clay Member and the lower
one is called the Bhaluka Sand Member, and is represented by yellowish
brown highly micaceous sand containing primary sedimentary structures,
such as, cross bedding, ripple marks etc. Palaeomagnetical studies showed
normal polarity of this formation and has been correlated with the Jaramillo
Event of Matuyama Reversed Polarity Epoch. It means that the Clay has
the age of about 0.97 to 0.90 million years. The depositional environment
of the Madhupur Clay is fluvial. [Md Hussain Monsur] |
