4. Problem Statement 1:
▪ Why such an irregularity in the elevation profile and topography?
▪ Pondicherry is in the Eastern Coast of India and there shouldn’t be much
change in elevation profile near the sea coast.
▪ What are the possible causes for such irregularity?
7. Inference:
▪ On field observations suggest that this crack is a “deeply incisedV-
shaped Ravine.”
▪ This ravine seems to be extending from the central area of the
university to almost near the sea.
8. 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., more
the gradient, deeper is the valley or the ravine.
▪ Coastal areas are known for very low gradients.
Need for an Explanation??
11. Inference:
▪ Presence ofAlternate Sandstone and conglomerate layers.
▪ Lithology of Pondicherry: Cuddalore Sandstone as the supracrust
covered by marine/fluvial deposits as regolith.
▪ Conglomerates are deposited in a area where they are not usually
found.
▪ Presence of rounded angular fragments in the conglomeritic layer.
12. Problem Statement 3:
▪ Conglomerate forms where a sediment of rounded clasts at least two
millimeters in diameter accumulates. It takes a strong water current
to transport and shape particles this large.
▪ Streams are a function of gradient => Deposition along the stream is
also a function of gradient.
▪ Coastal areas are known for very low gradients => Only sand and silt
are deposited…. Conglomerate??
Need for an Explanation??
14. Answer Statement 3:
▪ Conglomerate deposits => High gradient and high velocity.
▪ It is a well known as that the SouthWestern part of the Indian
Subcontinent is well elevated than the South Eastern Part.
▪ The conglomerates should be deposited somewhere in the central
part.
▪ There must be a “Shift in the slope” in the South Eastern Part that
led to the deposition of the Conglomerate.
16. Answer Statement 2 & 1:
▪ There could be a syn-sedimentary upliftment in the Eastern coast.
This explains the deposition of the conglomerate in the area.
▪ After the consolidation of the rock mass, there could be another
upliftment in the area.
▪ The torrential rain or stream flow in the area eroded the weak-zones
of the rock carving a beautiful ravine.
17. Clear indication of neo-tectonic activity
▪ Evidences:
1. The ravine is the major evidence to support our theory.
2. Conglomeritic Deposits also provides an indirect evidence pointing
to a change in slope of the area.
3. Recent seismic activity indicate a re-activated thrust fault system in
Pondicherry causing a M 5.5 earthquake in 2001.
21. References
▪ DEM Data Courtesy: Mr. Lakshmi Ramprasath, Research Scholar,
Dept. of Earth Sciences, Pondicherry University.
▪ Murthy, G P S., Subrahmanyam, AS., Murthy, K S R., Sarma, KV L N
S., 2012, Evidence of fault reactivation off Pondicherry coast from
marine 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/
22. THANK YOU!
A presentation by:
G N S SREE BHUVAN and
CVENKATESWAR REDDY
Integrated M.Sc. (Applied Geology) 2nd year.
