Lecture-56 || Geography by Ajeet Sir

Key Takeaways

• The Northern Plains of India originated either from the Tethys Sea's deposits or from river deposition; fossil evidence supports the river origin theory.
• The plains slope from west to east, with coarser sediments in the west and finer particles in the east due to decreasing river velocity.
• Reh and kalar are white salt and calcium carbonate crusts on the soil surface, formed by capillary rise of salts, common in drier parts of the plains.
• The entire region is covered by alluvial soil, which is classified into older bhangar (away from rivers, not flooded) and newer khadar (near rivers, annually flooded).
• Bhangar soil, when whitened by salt accumulation, is locally called 'bal sundari' in Bihar and Uttar Pradesh, indicating high salinity.
• The eastward slope of the plains causes waterlogging in Bihar, where such waterlogged lands are called 'tal' or 'chaus', used for makhana cultivation.
• The lecture emphasizes that the Northern Plains are geologically Quaternary, with a west-to-east gradient in both elevation and sediment particle size.