Beach cusp morphology on sand and mixed sand and gravel beaches, South Island, New Zealand

1999 ◽  
Vol 157 (3-4) ◽  
pp. 185-198 ◽  
Author(s):  
T.J. Nolan ◽  
R.M. Kirk ◽  
J. Shulmeister
Keyword(s):  
New Zealand ◽  
Gravel Beaches ◽  
Sand And Gravel ◽  
Beach Cusp

Motukoreaite, a new hydrated carbonate, sulphate, and hydroxide of Mg and Al from Auckland, New Zealand

1977 ◽  
Vol 41 (319) ◽  
pp. 389-390
Author(s):  
K. A. Rodgers ◽  
J. E. Chisholm ◽  
R. J. Davis ◽  
C. S. Nelson
Keyword(s):  
New Zealand ◽  
Olivine Basalt ◽  
Unit Cell ◽  
Rock Fragments ◽  
Alkali Olivine Basalt ◽  
Beach Rock ◽  
Wet Chemical ◽  
O 19 ◽  
Olivine Sand ◽  
Sand And Gravel

Motukoreaite occurs as relatively abundant, white, clay-like cement in both beach-rock and basaltic volcanic tuffs on the flanks of a small, extinct, late Pleistocene, basaltic cone at Brown's Island (Motukorea), within Waitemata Harbour, Auckland, New Zealand (36° 50′ S., 174° 35′ E.). The occurrence was originally recorded by Bartrum (1941) as ‘beach limestone’ found at two places of the island's shore. The beach-rock consists of a grain-supported fabric of poorly sorted, well-rounded, alkali-olivine basalt pebbles and granules, subangular to sub-rounded fresh olivine sand and abraded sand- and gravel-sized bioclasts in a colourless to pale yellow-green aphanocrystalline matrix of motukoreaite. Additional detritals include quartz, feldspar, and sedimentary rock fragments. Stereoscan examination of the surface of pieces of the cement prised from the beach-rock showed a box-work of plate-like crystals with a hexagonal form in which individuals measured about 3×3×0·02 microns (fig. 1).Wet-chemical analysis of a separate of the cement containing some 5 % quartz and traces of calcite and goethite gives SiO2 5·55, Al2O3 17·87, Fe2O3 0·73, CaO 0·92, MgO 22·98, MnO 0·70, ZnO 0·56, Na2O 0·71, K2O 0·10, CO2 9·32, SO3 10·00, H2O+ 19·62, H2O- 10·35, sum 99·41 %. The unit-cell formula using obtained unit-cell constants and measured specific gravity 1·43) is (Na0·73K0·07)∑0·80(Mg18·13Mn0·32Zn0·21)∑18·66Al11·15(CO3)6·22(SO4)3·97 (OH)51·1927·20H2O. Of several idealized formulae that may be proposed NaMg19Al12(CO3)6.5 (SO4)4(OH)54·28H2O is preferred.

In-situ Observations of Infragravity Response during Extreme Storms on Sand and Gravel Beaches

2020 ◽  
Vol 95 (sp1) ◽  
pp. 382
Author(s):  
Oliver Billson ◽  
Paul Russell ◽  
Mark Davidson ◽  
Tim Poate ◽  
Laurent Amoudry ◽  
...  
Keyword(s):  
In Situ Observations ◽  
Gravel Beaches ◽  
Sand And Gravel

Mixed sand and gravel beaches

2020 ◽  
pp. 317-341
Author(s):  
Alejandro López-Ruiz ◽  
Miguel Ortega-Sánchez ◽  
Miguel Á. Losada
Keyword(s):  
Gravel Beaches ◽  
Sand And Gravel
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