Post on 07-Jul-2018
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Curiosity about a
RavineAn attempt to unlock the mystery!
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Welcome to Pondicherry University
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Observation 1
Elevation profile along the path show
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Problem Statement 1:
▪Why such an irregularity in the elevation profile and topograph
▪ Pondicherry is in the Eastern Coast of India and there shouldn’t change in elevation profile near the sea coast.
▪ What are the possible causes for such irregularity?
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Observation 2
Presence of a huge crack as seen frGoogle Earth
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Field observation of the crack
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Inference:
▪
On field observations suggest that this crack is a “deeply incisedshaped Ravine.”
▪ This ravine seems to be extending from the central area of theuniversity to almost near the sea.
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Problem Statement 2:
▪ How did the Ravine form?
▪ What are the probable causes for it’s formation?
▪ The valleys and ravines are usually a function of gradient i.e., mthe gradient, deeper is the valley or the ravine.
▪ Coastal areas are known for very low gradients.
Need for an Explanation??
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Observation 3:
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Observation 3:
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Inference:
▪
Presence of Alternate Sandstone and conglomerate layers.
▪ Lithology of Pondicherry: Cuddalore Sandstone as the supracrcovered by marine/fluvial deposits as regolith.
▪ Conglomerates are deposited in a area where they are not usuafound.
▪ Presence of rounded angular fragments in the conglomeritic lay
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Answer Statement 3:
▪ Conglomerate deposits => High gradient and high velocity.
▪ It is a well known as that the South Western part of the Indian
Subcontinent is well elevated than the South Eastern Part.
▪ The conglomerates should be deposited somewhere in the cenpart.
▪ There must be a “Shift in the slope” in the South Eastern Partled to the deposition of the Conglomerate.
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The Grand Reconstruction
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Answer Statement 2 & 1:
▪ There could be a syn-sedimentary upliftment in the Eastern coa
This explains the deposition of the conglomerate in the area.
▪ After the consolidation of the rock mass, there could be anotheupliftment in the area.
▪ The torrential rain or stream flow in the area eroded the weak-zof the rock carving a beautiful ravine.
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Clear indication of neo-tectonic acti
▪ Evidences:
1. The ravine is the major evidence to support our theory.
2. Conglomeritic Deposits also provides an indirect evidence poito a change in slope of the area.
3. Recent seismic activity indicate a re-activated thrust fault syst
Pondicherry causing a M 5.5 earthquake in 2001.
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Pondicherry Area Remodelled using DE
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Evidence of Seismicity in Pondicher
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References
▪ DEM Data Courtesy: Mr. Lakshmi Ramprasath, Research ScholDept. of Earth Sciences, Pondicherry University.
▪ Murthy, G P S., Subrahmanyam, AS., Murthy, K S R., Sarma, K VS., 2012, Evidence of fault reactivation off Pondicherry coast fromarine geophysical data, Current Science, 1446-1449.
▪ Ravine’s Picture courtesy :https://sruthinlal.wordpress.com/2014/10/18/a-ravine-and-an-adventure-one-day-at-pondy/
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THANK YOU!
A presentation by:
G N S SREE BHUVAN andC VENKATESWAR REDDY
Integrated M.Sc. (Applied Geology) 2nd year.