The Boulder Bank ( Māori: ''Te Taero a Keropa'' or ''Te Tāhuna o Tama-i-ea'') is a very unusual naturally formed landform in

Nelson Nelson may refer to: Arts and entertainment * ''Nelson'' (1918 film), a historical film directed by Maurice Elvey * ''Nelson'' (1926 film), a historical film directed by Walter Summers * ''Nelson'' (opera), an opera by Lennox Berkeley to a lib ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It is a long stretch of

rocky ''Rocky'' is a 1976 American independent film, independent sports drama film directed by John G. Avildsen and written by and starring Sylvester Stallone. It is the first installment in the Rocky (film series), ''Rocky'' franchise and also star ...

substrate which begins at the Mackay Bluff and ends at the Cut of the Nelson

Harbour A harbor (American English), or harbour (Commonwealth English; see American and British English spelling differences#-our, -or, spelling differences), is a sheltered body of water where ships, boats, and barges can be Mooring, moored. The t ...

. Haulashore Island was once a part of the Boulder Bank, but the Cut made it an island, and it is no longer connected to the Boulder Bank. The Boulder Bank separates Tasman Bay and the Nelson Haven and is managed as a scenic reserve by the Department of Conservation. Land access is gained along Boulder Bank Drive, signposted at the northern end of Nelson Haven on .

Geology and geography

The Boulder Bank is composed of

granodiorite Granodiorite ( ) is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gra ...

. The source of this rock is Mackay Bluff. It is still debated what process or processes have resulted in this odd structure.

Longshore drift Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle, shells) along a coast parallel to the shoreline, which is dependent on the angle of incoming w ...

, however, is the most accepted hypothesis for creation. The main objection to longshore drift as the explanation is that Tasman Bay does not receive enough wave action to move the large boulders in a south-westerly direction. Studies have been conducted since 1892 to determine speed of boulder movement. Rates of the top course

gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

movement have been estimated at a year.

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 wide entrance was operational. Today the Cut is wide and dredged every six months to maintain a depth of .

Lighthouse

The Boulder Bank Lighthouse was erected in 1862. It is located near the port end of the Boulder Bank and was New Zealand's second permanent lighthouse. It is registered with the Historic Places Trust as a category I structure with registration number 41.

Notes

References

* Hartstein, ND and Warren Dickinson, W (2005
Wave energy and clast transport in eastern Tasman Bay, New Zealand
'' Earth Surface Processes and Landforms'', 31:6 (703–714). * Warren, Karen. ''Rolling Stones: Nelson's Boulder Bank, Its Place in Our History and Hearts'', 320 pp, 2009, Nikau Press, Nelson, New Zealand.

External links

The story of the Boulder Bank

The Nelson Boulder Bank
{{coord, -41.2344, 173.2964, format=dms, region:NZ_type:landmark_dim:5000, display=title Spits of New Zealand Geography of Nelson, New Zealand Barrier islands Landforms of the Nelson Region Rock formations of New Zealand