Earthcache Questions
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1. What type of rock forms the sea stack at Eagles Nest, and how did it resist erosion compared to surrounding materials?
2. How does the stack formation, offshore rock reefs and low-tide flats influence coastal erosion and wave energy at Eagles Nest?
Eagles Nest is a striking sandstone sea stack located on a broad rock platform, periodically submerged at high tide. It is a prominent coastal landform shaped by ongoing marine erosion, where softer surrounding material has been worn away over time, leaving the more resistant sandstone standing.
Eagles Nest is composed primarily of sandstone, a sedimentary rock made from compacted sand grains. Initially erosion along a fault running NW to NE isolated the stack. Over time the softer surrounding materials eroded faster under wave action and weathering, while the more resistant sandstone remained intact. This process formed the dramatic sea stack we see today.
Positioned along the eastern shoreline, the sea stack is adjacent to a 250-metre-long platform beach, which lies at the base of 40-metre-high coastal bluffs. The beach itself is fronted by extensive low-tide rock flats and several offshore rock reefs, which play a crucial role in shaping local wave energy. The presence of the stack and the surrounding reefs and rock platform significantly dampens incoming wave energy, reducing average wave heights to around 1 metre. This reduces wave energy reaching the shore, helping to slow erosion of the beach and surrounding landforms.
Beyond its geological interest, Eagles Nest is also a popular scenic location, easily accessible from a nearby roadside car park, offering panoramic views and photo opportunities of the dramatic coastline.