There have been reports that Andhra Pradesh Tourism Development Corporation (APTDC) plans to put up a tourist facility at “Erra matti dibbalu” (“Red Sand Hills”) near Bhimunipatnam. The reports have caused concern among certain sections of the public as well as those from the scientific community. This site is the last remaining area having the unique red sand dune formations which are such a rarity. It is felt that establishing a tourism facility there will deeply impact the pristine nature of the area and seal the fate of this fragile ecological wonder.
When the sea receded it left behind huge volumes of clay and silt. Subsequently, the beach sand swept over the clay and silt, and over time this “Aeolian” (carried by wind) sand covered the earlier soil forming large sand dunes. The clay and silt under the sand then “baked” in the sun much like a brick gets baked in a kiln leading to the peculiar red earth. Later, action of the wind and flowing water caused the deeply gullied characteristic landscape. The red colour of the dunes is said to be due to the “ferrogination” of “haemitite”. This simply means that iron rich material haemitite coated the loose sand grains and when it got exposed to the elements the stuff oxidized over a period of time. Just like a nail exposed to salty air would get corroded and appear red in colour.
By no means is the explanation of the process that caused the red hills definitive. Other theories suggest that the main cause of the formation is mainly due to “Fluvial” meaning action caused by flowing water. And that it happened in a period of tectonic quiescence – a quiet period without too much tectonic activity. Yet others are convinced that much of what we see today is due to the “Neotechtonic” activity, this fancy word simply means tectonic activity that took place in the recent past, which is around 6,000 years ago. Dr. Srinivas Madabhushi points out that the sudden change in the flow of the Gosthani River, the gap in the Bhimunipatnam ridge, the pattern of fractures and several other clues clearly indicate a series of recent tectonic activities.