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Geology/Cave Structures.



Dear Nusrat

Are Caves always Closed Structures ?. i.e. The Entry and Exit Points are always the same. There can be multiple entry points to enter the cave structure but the entry points will be always the exit points ?. Exit point i mean is coming out of the cave structure. For example in a Theater hall the entry (To enter the Cinema Hall) and exit (To exit the Cinema Hall) points may be different.

Will there be any specific advantages if exit points are created /constructed (only if exit points do not exist) within the cave
structures ?

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

Prashant, (I follow a standard way to address. It is always just the first name, so please do not mind)

Caves are formed due to the movement of underground water, like a river flowing in-n-out through a mountain or through subsurface rocks. Carbonates are the most suitable type of rock as they get dissolved, and form stalactites and stalagmites in amazing shapes. As far as I understand the underground caves may or may not have an exit or entrance, as such (closed). Their presence is proved when the near surface ceiling (of caves) collapses, resulting in the pot-holes that some time may be gigantic in size. Some rivers may enter the ground and keep flowing in the subsurface and do not come out i.e. no exit as such. In Spain (Morella region)I have seen a river that just disappears on the surface (extensively fractured carbonate) and then emerges from a vertical cliff after a considerable distance, so it does not have opening at the entrance. In mountainous  areas a river may enter at higher levels and then flows-out from lower areas; here we find both entrance and exit.

As the water flows downwards the entrance and exit points have to be at different levels. The picture you have pasted may be of two outlets of a stream flowing from a higher entry point.

Hope the answer is of help to you.


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Nusrat Kamal Siddiqui (Mr)


I am a petroleum exploration geologist with about 40+ years of diversified experience. I can answer questions on stratigraphy, log interpretation, field studies based on set of logs and core results, general geology etc. Can provide guidance for career planning in earth sciences. Can not help in questions about hard rocks, igneous petrology & mineralogy, sequence stratigraphy and seismic.


Petroleum Exploration - field geology, stratigraphy, prospect generation, interpretation of satellite imagery (visual), log interpretation.

Retired in May, 2006 as Senior Manager Exploration from Pakistan Petroleum Limited after serving 26 years. Since then continuing in active service with petroleum exploration companies.A cumulative experience of about 40 years covers 30 years in petroleum exploration, 5 years hydrogeology experience in Libya, and about 5 years of dam geology in Pakistan.

-AAPG Bulletin (Vol.88, July, 2004); paper on Sui Main Limestone (Eocene), a prolific gas reservoir in Pakistan. -Have presented papers on diversified topics ranging from spirituality, flood control, remote sensing and off course geology in France, Nepal, Bangladesh, Sri Lanka, UAE, Kashmir, India and Pakistan that have been published in respective Special Proceedings. -ONGC Bulletin(India) Vol. 44, Number 2, December, 2009; Chapter 19.A & 19.B on basin architecture and stratigraphy of Pakistan, p.402-474.

BSc Honours in Geology and Master of Science in Petroleum and Structural Geology. PGD from ITC, The Netherlands.

Awards and Honors
-Remained Active Member of AAPG from 1990-2006; founding member of PAPG (a local affiliate of AAPG). -Life member of SEGMITE & AGID, and Senior Editor of SEGMITE magazine. -Member of the Board of Studies, i. Department of Petroleum & Gas Engineering (BUITMS, Quetta), and ii. Geology Department, Sindh University, Jamshoro. -Member of Stratigraphic Committee of Pakistan. -Represented Mining Journal, UK in Pakistan till 2007. -Chairman of Annual Technical Conference (ATC)& Oil Show, an SPE/PAPG annual event, in 2003. -Chairman Technical Committee (ATC, 2002).

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