The Coastal Red Sand Dunes, also known as ‘Erra Matti Dibbalu’, located in Visakhapatnam, Andhra Pradesh, are gaining attention for their geological importance. This site was declared a geo-heritage site by the Geological Survey of India in 2014 and listed under the category of ‘protected sites’ by the Andhra Pradesh government in 2016. The unique geological features and continuous evolution of the site make it significant for the study of climate change and prehistoric human activities.
About Erra Matti Dibbalu
Erra Matti Dibbalu is situated about 20 km north-east of Visakhapatnam city and approximately 4 km southwest of Bheemunipatnam. It is one of several sites in Visakhapatnam recognised for their geological significance. Similar sand deposits have been reported from only three places in the tropical regions of South Asia, namely Teri Sands in Tamil Nadu, Erra Matti Dibbalu in Visakhapatnam, and a site in Sri Lanka.
Unique Sedimentary Characteristics
The red sediments of Erra Matti Dibbalu exhibit a continuous evolution, representing the late Quaternary geological age, which spans from 2.6 million years ago to the present. These sediments display various geomorphic landforms and features including gullies, sand dunes, buried channels, beach ridges, paired terraces, valleys within valleys, wave-cut terraces, knick points, and waterfalls. The top light-yellow sand unit, deposited around 3,000 years ago, has not attained red colouration as the sediments remain geochemically unaltered. Additionally, these sediments do not contain fossils and are deposited over the Khondalite basement, a regional rock with high-grade metamorphism and granulite rock formation.
Significance of Studying Erra Matti Dibbalu
The study of Erra Matti Dibbalu can contribute to an understanding of climate change impacts, as the site has witnessed both glacial and warm periods. Estimated to be between 18,500 to 20,000 years old, the site’s geological evolution is linked to the last glacial period. About 18,500 years ago, the sea was at least 5 km behind the current shoreline. Since then, continuous active changes have occurred, indicating the ongoing effects of climate change.
Archaeological Importance
Erra Matti Dibbalu also holds archaeological significance. Studies of artefacts from the site suggest an Upper Palaeolithic horizon and cross-dating to the Late Pleistocene epoch around 20,000 BC. Excavations in the region have revealed stone implements from three distinctive periods and pottery from the Neolithic era, indicating that the site was occupied by prehistoric humans.
The Coastal Red Sand Dunes, or Erra Matti Dibbalu, embody a rich geological and archaeological repository, enhancing our understanding of the Earth’s history, climatic transformations, and human evolution. Accordingly, it is vital to continue protection and research efforts for this remarkable site.
