GPR Investigation of the Great Dune Ridge, Naglių Nature Reserve, Lithuania : A Historic Landscape Threatened by Natural and Anthropogenic Causes

Abstract

Since the beginning of the 19th century, aeolian sand dunes, which are piles of loose sediment, have dominated the Curonian Spit. The sediment in aeolian dunes has been eroded and transported by wind. The World Heritage Convention suggests hundreds of years ago, settlers who inhabited the Curonian Spit cleared vegetation and deforested the Curonian spit (UNESCO 2021). This deforestation is what has allowed aeolian processes to take over and create large sand dunes, burying artifacts and soils from this past civilization. Analysis of the dunes are important to explore buried stratigraphy and soil layers. These dunes are continuing to migrate from prevailing winds. We expect to see high-angle oblique-tangential reflections, as the dunes create a steep ridge, which then sand falls over the edge of and creates diagonal layers. Sand dune movement is important, as it has buried settlements and soils, the latter of which is what we are focusing on. Ground penetrating radar (GPR) is a noninvasive way to look at the subsurface of the sand dunes. Using GPR with different frequencies, the electromagnetic pulses sent out have distinct usefulness. By using low frequency pulses, we are able to see further into the subsurface, but at a trade-off with definition quality.