• Denudation: denudation involves the processes that cause the wearing away of Earth’s surface by moving water, ice, wind, and waves. This leads to a reduction in elevation and in relief of landforms and of landscapes.
    • Denudation = (Weathering + Erosion)
denudation
  • Denudation chronology means reconstruction of denudational history of a given region. The Earth‘s surface has a history that leaves traces in present-day landscapes and sediments. These traces make possible the partial reconstruction of long-term landscape change. This is primarily based on historical or chronological approach of landform study which involves the basic concepts such as:
    • ‘There is sequential change in landforms through time’,
    • ‘Principles of uniformitarianism‘
    • ‘Cyclic nature of earth ’s history ’
    • ‘Palimpsest topography ‘and
    • Davisian model of ‘cyclic evolution of landforms’.
  • The primary goal of this approach is to reconstruct the chronological history of denudation of a given region known as denudation chronology and according to R J Small the goal of this approach is to identify, date and interpret planation surfaces developed in past cycles and sub cycles of erosion on the basis of evidences of drainage development, river capture, relic surfaces and past tectonic events.
  • Oxford Definition: Branch of land-form studies that deals with the historical development of landscapes by denudation, especially during pre-Quaternary time. Evidence for developmental stages is provided by studies of erosion surfaces and their mantling deposits, drainage patterns, stream long-profiles, and geologic structures.
  • An attempt is made to reconstruct the geomorphic history of the region concerned on the basis of present and remnant (relict) land forms following the dictum of ‘present is key to the past’.
  • Historical approach or denudation chronology approach involves description of landform evolution through successive stages of geological time or say cyclic time involving longer geological time and larger spatial scales. ‘In this type of analysis the emphasis is placed on the historical development of the landscape, based on the cyclic concept of Davis, on the assumption that evidence of the past character of the landscape is still apparent in its present form ’.
  • In fact, denudation chronology is based on the concept of palimpsest topography’ which means such a surface which bears the imprints of geomorphological processes during past geological periods after partially erased initial imprints (features) in the beginning.
    • Palimpsest refers to that manuscript which has been written, erased, and rewritten several times. Similarly, palimpsest topography represents complex topographic features of a region which have been written (characterized by topographic features) by geomorphological processes, erased (previous geomorphological features partially destroyed by succeeding pro cesses) and rewritten (production of new reliefs on older surfaces) several times.
  • The degree of precision of landform analysis rests on deductive power of the researcher and level of qualitative and quantitative description of relic features.
  • The denudation chronology approach suffers from certain perceptible weaknesses such as:
    • An important criticism which has been levelled against the denudation chronology approach is that it succeeds in explaining directly only very small parts of the existing landscape, namely the fragments of former (erosion) surfaces which have been dissected and almost totally destroyed in some cases by more recent erosion‘.
    • Secondly, Historical approach is highly deductive and speculative because the old erosion surfaces and remnant forms have been so greatly modified by subsequent processes that it becomes difficult or say impossible to find out their original forms and initial heights.
    • The dating of erosion surfaces is also highly speculative as valid geological evidences are not available.
denudation chronology

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Rohit

Selective content according to the requirement of the topics.
Thank you !
May I suggest to conduct a quality-Mains test series on regular basis with your feedback on written answers ?

Aakib

Crisp, selective and well explained topic.Thank you Team LotusArise❤️