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Geology and geography
Headlands and bays are often found together on the same stretch of coastline. Headlands and bays form on concordant coastlines, where bands of rock of alternating resistance run perpendicular to the coast. Bays form where weak (less resistant) rocks (such as sands and clays) are eroded, leaving bands of stronger (more resistant) rocks (such as chalk, limestone, granite) forming a headland, or peninsula. Refraction of waves occurs on headlands concentrating wave energy on them, so many other landforms, such as caves, natural archs and stacks, form on headlands. Wave refraction disperses wave energy through the bay, and along with the sheltering effect of the headlands this protects bays from storms. This effect means that the waves reaching the shore in a bay are weaker than the waves reaching the headland and the bay is thus a safer place for water activities like surfing or swimming
Beach stability
Beaches are dynamic geologic features that can fluctuate between advancement and retreat of sediment. The natural agents of fluctuation include waves, tides, currents, and winds. Man-made elements such as the interruption of sediment supply, such as a dam, and withdrawal of fluid can also affect beach stabilization.[1] A headland bay beach can be classified as being in three different states of sedimentation. Static equilibrium refers to a beach that is stable and does not experience littoral drift or sediment deposition or erosion.[2] Waves generally diffract around the headland(s) and near the beach when the beach is in a state of static equilibrium. Dynamic equilibrium occurs when the beach sediments are deposited and eroded at approximately equal rates.[2] Beagkjhfiuches that have dynamic equilibrium are usually near a river that supplies sediment and would otherwise erode away without the river supply. Unstable beaches are usually off the ocean have have little land extending into it.
References
- ^ Schwartz, M. (2005). "Encyclopedia of Coastal Science" . Springer. ISBN 13 978-1-4020-1903-6 p399
- ^ a b Benedet, L., Klein, A., and Hsu, J. (2004). "Practical Insights and Applications of Empirical Bay Shape Equations". ICCE.
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