title: An Integrated Stratigraphy of Tauranga Harbour

authors: MacPherson, David

subjects: Tauranga

abstract: Tauranga Basin is a Quaternary basin filled with successions of terrestrial and coastal sediments. The largest feature of Tauranga Basin is Tauranga Harbour, a 570km2 estuary. This is home to the Port of Tauranga, New Zealands largest export port. Studies conducted following an initial study by Davis and Healy (1993) have found complex distributions of the sediments within the dredged shipping channel. This research used 86 vibracores and limited seismic data to identify four main facies within the shallow subsurface of the dredged channel and establish their distribution.
Four facies were identified within the shallow subsurface: the Volcanic Sand facies, a silt to fine sand volcaniclastic succession; the Silt facies, a silt to very fine sand lacustrine deposit; the Coastal Sands facies, a medium to coarse coastal sand deposit; and the Pumiceous Sand Facies, a medium to coarse sand succession with abundant pumice.

Within the dredged shipping channel, the Volcanic Sands and Silt facies outcrop at the surface, and appear as ridges in the subsurface. Draped over these ridges is the Coastal Sands facies, which in some cores is overlain by Pumiceous Sands. The Volcanic Sands facies represents a succession of tephra deposits, with some reworking between depositional events. In the Maunganui Roads region of the harbour this is overlain by the lacustrine Silt facies, formed from the reworking of the Volcanic Sands. The region was then inundated by the Holocene marine transgression, leading to the deposition of the Coastal Sands facies, sourced from offshore. This Coastal Sands facies is then overlain in areas by Pumiceous Sands, small mobile sand waves that exist within the shipping channel. These are formed following the erosion of ignimbrite cliffs around the harbour, with some input from the outside the harbour. This represents a change in source for sedimentation in the harbour.

An updated model of the paleogeographic development of the harbour is presented, using data from this and other studies. This model shows the presence of a braided river flowing through Stella Passage, before the development of a lake and the subsequent Holocene marine transgression leading to the evolution of the sand spit and Matakana barrier island.

text: An Integrated Stratigraphy of Tauranga Harbour Tauranga Basin is a Quaternary basin filled with successions of terrestrial and coastal sediments. The largest feature of Tauranga Basin is Tauranga Harbour, a 570km2 estuary. This is home to the Port of Tauranga, New Zealands largest export port. Studies conducted following an initial study by Davis and Healy (1993) have found complex distributions of the sediments within the dredged shipping channel. This research used 86 vibracores and limited seismic data to identify four main facies within the shallow subsurface of the dredged channel and establish their distribution.
Four facies were identified within the shallow subsurface: the Volcanic Sand facies, a silt to fine sand volcaniclastic succession; the Silt facies, a silt to very fine sand lacustrine deposit; the Coastal Sands facies, a medium to coarse coastal sand deposit; and the Pumiceous Sand Facies, a medium to coarse sand succession with abundant pumice.

Within the dredged shipping channel, the Volcanic Sands and Silt facies outcrop at the surface, and appear as ridges in the subsurface. Draped over these ridges is the Coastal Sands facies, which in some cores is overlain by Pumiceous Sands. The Volcanic Sands facies represents a succession of tephra deposits, with some reworking between depositional events. In the Maunganui Roads region of the harbour this is overlain by the lacustrine Silt facies, formed from the reworking of the Volcanic Sands. The region was then inundated by the Holocene marine transgression, leading to the deposition of the Coastal Sands facies, sourced from offshore. This Coastal Sands facies is then overlain in areas by Pumiceous Sands, small mobile sand waves that exist within the shipping channel. These are formed following the erosion of ignimbrite cliffs around the harbour, with some input from the outside the harbour. This represents a change in source for sedimentation in the harbour.

An updated model of the paleogeographic development of the harbour is presented, using data from this and other studies. This model shows the presence of a braided river flowing through Stella Passage, before the development of a lake and the subsequent Holocene marine transgression leading to the evolution of the sand spit and Matakana barrier island.

year: 2016

title: Monoids with tests and the algebra of possibly non-halting programs

authors: Jackson, Marcel

subjects: Science & Technology

abstract: We study the algebraic theory of computable functions, which can be viewed as arising from possibly non-halting computer programs or algorithms, acting on some state space, equipped with operations of composition, if-then-else and while-do defined in terms of a Boolean algebra of conditions. It has previously been shown that there is no finite axiomatisation of algebras of partial functions under these operations alone, and this holds even if one restricts attention to transformations (representing halting programs) rather than partial functions, and omits while-do from the signature. In the halting case, there is a natural “fix”, which is to allow composition of halting programs with conditions, and then the resulting algebras admit a finite axiomatisation. In the current setting such compositions are not possible, but by extending the notion of if-then-else, we are able to give finite axiomatisations of the resulting algebras of (partial) functions, with while-do in the signature if the state space is assumed finite. The axiomatisations are extended to consider the partial predicate of equality. All algebras considered turn out to be enrichments of the notion of a (one-sided) restriction semigroup

text: Monoids with tests and the algebra of possibly non-halting programs We study the algebraic theory of computable functions, which can be viewed as arising from possibly non-halting computer programs or algorithms, acting on some state space, equipped with operations of composition, if-then-else and while-do defined in terms of a Boolean algebra of conditions. It has previously been shown that there is no finite axiomatisation of algebras of partial functions under these operations alone, and this holds even if one restricts attention to transformations (representing halting programs) rather than partial functions, and omits while-do from the signature. In the halting case, there is a natural “fix”, which is to allow composition of halting programs with conditions, and then the resulting algebras admit a finite axiomatisation. In the current setting such compositions are not possible, but by extending the notion of if-then-else, we are able to give finite axiomatisations of the resulting algebras of (partial) functions, with while-do in the signature if the state space is assumed finite. The axiomatisations are extended to consider the partial predicate of equality. All algebras considered turn out to be enrichments of the notion of a (one-sided) restriction semigroup

year: 2015-03

title: Iwi case study report- Tarawera river: Tuwharetoa ki Kawerau, Te Arawa and Ngati Awa

authors: Dodd, Materoa

subjects: Iwi land rights

abstract: There is a deep sense of injustice and creeping despair that the cultural life of the Tarawera River has been destroyed. Cultural lore has been reduced to a perspective of the dominant cultures’ rule of law. The plea for the cultural voice of the Tarawera River to be heard echoes throughout this research, yet the silence of the response is deafening. This research informs on the cultural story of the Tarawera River, it examines the ways in which the relationship between Te Arawa, Tūwharetoa Ki Kawerau and Ngāti Awa and the Tarawera River changed since the discharge of effluent from pulp and paper mills into the river began nearly half a century ago. The research reported on here involves action research approached and informed by Māori epistemologies and what has come to be known as ‘kaupapa Māori research’, an approach that privileges indigenous values, attitudes and practices.

text: Iwi case study report- Tarawera river: Tuwharetoa ki Kawerau, Te Arawa and Ngati Awa There is a deep sense of injustice and creeping despair that the cultural life of the Tarawera River has been destroyed. Cultural lore has been reduced to a perspective of the dominant cultures’ rule of law. The plea for the cultural voice of the Tarawera River to be heard echoes throughout this research, yet the silence of the response is deafening. This research informs on the cultural story of the Tarawera River, it examines the ways in which the relationship between Te Arawa, Tūwharetoa Ki Kawerau and Ngāti Awa and the Tarawera River changed since the discharge of effluent from pulp and paper mills into the river began nearly half a century ago. The research reported on here involves action research approached and informed by Māori epistemologies and what has come to be known as ‘kaupapa Māori research’, an approach that privileges indigenous values, attitudes and practices.

year: 2002-02