Boulder Bank
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The Boulder Bank is a very unusual naturally formed land form in Nelson, New Zealand. It is a 13 kilometer long stretch of rocky substrate which begins at the Mackay Bluff and ends at the Cut of the Nelson Harbour. Haulashore Island was once apart of the Boulder Bank, but after the Cut being made is an island, and no longer connected to the Boulder Bank. The Boulder Bank separates Tasman Bay and the Nelson Haven.
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[edit] Geology & Geography
The Boulder Bank is composed of granodiorite [1]. The source of this rock is Mackay Bluff. It is still debated what process or processes have resulted in this odd structure. Longshore drift however is the most accepted hypothesis for creation. The main objection for longshore drift is that Tasman Bay does not receive enough wave action to move the large boulders in a south west direction. Studies have been conducted since 1892 to determine speed of boulder movement. Rates of the top course gravel movement have been estimated at 7.5 meters a year [1].
[edit] The Cut
The Cut was made to enable the Nelson port to allow the increasing demands of sea transport for the Tasman area. Construction started in 1903 and in 1905 a 61 meter wide entrance was operational [2]. Today the Cut is 150 meters wide and dredged every six months to maintain a depth of 10 meters [2].
[edit] Lighthouse
There is a small light house which was erected in 1862 [3]. It is located near the port end of the Boulder Bank.
[edit] External links
[edit] References
- ^ a b M.R. Johnson (2001). "Nelson Boulder Bank". New Zealand Journal of Geology and Geophysics 44: 79–88.
- ^ a b Cawthron Institute (1976). History & Natural History of the Boulder Bank. Nelson Haven. Nelson, New Zealand: Cawthron Institute.
- ^ Mark Phillips (2005). [www.newzealandlighthouses.com/nelson_boulder_bank.htm New Zealand Lighthouses]. Retrieved on 2007-12-01.
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