title: Geology of the northern Mamaku Plateau

authors: Morgan, Michael Denis

abstract: The geology of the northern Mamaku Plateau is dominated by the rhyolitic Mamaku and Waimakariri lgnimbrites, although exposures of the dacitic Waiteariki Ignimbrite are common in river gorges. 

The Mamaku lgnimbrite comprises 4 flow units (sheets 1 to 4). The base of sheet 2 (the bulk of the ignimbrite) is an uncompacted pyroclastic breccia to lapilli tuff grading into a moderate to strongly welded zone, often lenticulitic. The upper zone is incipiently welded, often light pinkish grey, with poor to moderate crystal contents. Fossil fumeroles are common in the upper middle of the flow, devitrification and vapour phase alteration is extensive. The upper zone of the Waimakariri Ignimbrite is usually light grey and incipiently welded. Towards the lower middle of the flow this grades down into a welded lenticulite, occasionally eutaxitic. The base is usually an incipiently welded pyroclastic breccia enriched in lithics. This ignimbrite has a poor to moderate crystal content, is composed of at least three flow units and often has an underlying Plinian airfall. Gas escape structures appear in distal outcrops.

The unwelded top of the Waiteariki Ignimbrite is often eroded. Usually only the middle of the flow, a densely welded lenticulitic with eutaxitic texture is present. The base of the flow is a moderately devitrified, incipiently welded, pyroclastic breccia to fine tuff. Evidence suggests the Waiteariki Ignimbrite comprises 2 cooling units both of which are crystal rich.

With increasing distance from source plagioclase crystal percentages, pumice size and pumice percentages decrease in the Mamaku Ignimbrite (sheet 2). For the Waimakariri Ignimbrite, there is a decrease in crystal lengths with distance from source (assumed to be the Taupo Volcanic Zone). There is an increase in crystal percentages from a medial to distal position, and a moderate increase in pumice percentages. This is explained by elutruation of vitric material from the Waimakariri as a co-ignimbrite air fall ash concentrating pumice and crystals.

No relationship exists between crystal length and vertical position in the Mamaku ignimbrite. Pumice percentages often increase towards the top of the flow, while pumice numbers increase towards the middle of the flow. Welding is at a minimum at the base, at a maximum in the lower middle of the outcrop, reducing towards the top of the flow. Phenocryst increase towards the base of sheet 2 is attributed to welding/compaction. No relation exists between crystal length and vertical position in the Waimakariri Ignimbrite; pumice percentages and size increase towards the base of the flow, while pumice numbers often increase towards the base and top of the flow. 

Horizontal sections over distances of 194 and 350 m for the Mamaku and Waimakariri Ignimbrites respectively, demonstrated that they are relatively homogeneous over short distances.

Both the Mamaku and Waimakariri Ignimbrites traveled as moderately fluidized laminar flows, but the surge deposits separating Mamaku flow units were turbulent as were parts of distal Waimakariri. The surges (probably foward jetting from the front of the flow) imply the Waimakariri flowed faster than the Mamaku Ignimbrite. A new flow unit is presented, perhaps more applicable to distal large ignimbrite eruptions, than the standard ignimbrite flow unit. Most field evidence indicated the Mamaku and Waimakariri Ignimbrites were emplaced en masse. The diversity of facies in both Mamaku and Waimakariri Ignimbrites implies a single large pyroclastic flow can operate under several flow regimes, dependent to some extent on local paleo-surface conditions.

text: Geology of the northern Mamaku Plateau The geology of the northern Mamaku Plateau is dominated by the rhyolitic Mamaku and Waimakariri lgnimbrites, although exposures of the dacitic Waiteariki Ignimbrite are common in river gorges. 

The Mamaku lgnimbrite comprises 4 flow units (sheets 1 to 4). The base of sheet 2 (the bulk of the ignimbrite) is an uncompacted pyroclastic breccia to lapilli tuff grading into a moderate to strongly welded zone, often lenticulitic. The upper zone is incipiently welded, often light pinkish grey, with poor to moderate crystal contents. Fossil fumeroles are common in the upper middle of the flow, devitrification and vapour phase alteration is extensive. The upper zone of the Waimakariri Ignimbrite is usually light grey and incipiently welded. Towards the lower middle of the flow this grades down into a welded lenticulite, occasionally eutaxitic. The base is usually an incipiently welded pyroclastic breccia enriched in lithics. This ignimbrite has a poor to moderate crystal content, is composed of at least three flow units and often has an underlying Plinian airfall. Gas escape structures appear in distal outcrops.

The unwelded top of the Waiteariki Ignimbrite is often eroded. Usually only the middle of the flow, a densely welded lenticulitic with eutaxitic texture is present. The base of the flow is a moderately devitrified, incipiently welded, pyroclastic breccia to fine tuff. Evidence suggests the Waiteariki Ignimbrite comprises 2 cooling units both of which are crystal rich.

With increasing distance from source plagioclase crystal percentages, pumice size and pumice percentages decrease in the Mamaku Ignimbrite (sheet 2). For the Waimakariri Ignimbrite, there is a decrease in crystal lengths with distance from source (assumed to be the Taupo Volcanic Zone). There is an increase in crystal percentages from a medial to distal position, and a moderate increase in pumice percentages. This is explained by elutruation of vitric material from the Waimakariri as a co-ignimbrite air fall ash concentrating pumice and crystals.

No relationship exists between crystal length and vertical position in the Mamaku ignimbrite. Pumice percentages often increase towards the top of the flow, while pumice numbers increase towards the middle of the flow. Welding is at a minimum at the base, at a maximum in the lower middle of the outcrop, reducing towards the top of the flow. Phenocryst increase towards the base of sheet 2 is attributed to welding/compaction. No relation exists between crystal length and vertical position in the Waimakariri Ignimbrite; pumice percentages and size increase towards the base of the flow, while pumice numbers often increase towards the base and top of the flow. 

Horizontal sections over distances of 194 and 350 m for the Mamaku and Waimakariri Ignimbrites respectively, demonstrated that they are relatively homogeneous over short distances.

Both the Mamaku and Waimakariri Ignimbrites traveled as moderately fluidized laminar flows, but the surge deposits separating Mamaku flow units were turbulent as were parts of distal Waimakariri. The surges (probably foward jetting from the front of the flow) imply the Waimakariri flowed faster than the Mamaku Ignimbrite. A new flow unit is presented, perhaps more applicable to distal large ignimbrite eruptions, than the standard ignimbrite flow unit. Most field evidence indicated the Mamaku and Waimakariri Ignimbrites were emplaced en masse. The diversity of facies in both Mamaku and Waimakariri Ignimbrites implies a single large pyroclastic flow can operate under several flow regimes, dependent to some extent on local paleo-surface conditions.

year: 1986

title: Dairy calves' preference for rearing substrate

authors: Worth, Gemma

subjects: Dairy calves

abstract: Rearing substrate is an important component of the pre-weaning environment of dairy calves. Traditional substrate types, such as sawdust, are becoming difficult and/or expensive for farmers to obtain in New Zealand. Therefore, there is a need to evaluate alternative rearing substrates for dairy calves that that are economically viable for farmers, readily available and provide an acceptable level of animal welfare. The preference of dairy calves for four different rearing substrates and the effects on behaviour and physiology were evaluated. At 1 wk of age, 24 calves were housed in groups of four, in pens which were evenly divided into four rearing substrates: sawdust, rubber, sand and stones. During the first 3 d calves were given free access to all four substrates. Calves were then restricted to each substrate type for 48 h. In order to rank preference, calves were subsequently exposed to two surfaces simultaneously for 48 h until calves experienced all six treatment combinations. Finally, calves were given free access to all four substrates simultaneously for 48 h. Lying behaviour and location in the pen was recorded for 24 h at the end of each experimental period using handycams and accelerometers. Preference was determined based on lying times on each substrate. The insulating properties of each substrate were assessed using iButtons®. 
During the initial free choice period, the proportion of time spent standing (p < .001) and lying (p < .001) was influenced by substrate. Calves spent a higher proportion of time on sawdust (88%) than all other substrates (rubber: 6%, sand: 4% and stones: 3%). 
When restricted to each substrate, calves spent more (p <.05) time running on sawdust, rubber and sand compared to calves on stones. There were no effects (p > .05) of rearing substrate on the frequency of jumps, buck/kicks, head to object and mount/frontal pushing. Calves spent more (p < .05) time lying on sawdust and rubber in comparison to sand and stones. There were no effects (p > .05) of rearing substrate on the number and duration of lying bouts. We detected no effect (p > .05) of rearing substrate on concentrations of cortisol, lactate, glucose, or white blood cell, neutrophil and lymphocyte count or the neutrophil:lymphocyte ratio. The insulating properties were greatest for sawdust and lowest for sand.
During the pairwise choice period, calves had a strong preference for one substrate over another, spending on average, 89% of their time on the preferred surface. Calves preference ranking was for sawdust, rubber, sand then stones as determined by the proportion of time spent on each surface. At the end of the study, when given free access to all rearing substrates again, calves spent a higher proportion of time on sawdust (85%) than all other substrates (rubber: 5%, sand: 7% and stones: 3%). 
In conclusion, dairy calves showed a clear preference for sawdust over rubber, sand and stones. This preference remained consistent over the course of the study. The calves’ preference for sawdust may be associated with the physical and thermal properties in comparison to the alternative substrates. However, factors such as cost to the farmer, availability and practicality of alternative substrates need to be considered along with animal preferences before any recommendations can be made.

text: Dairy calves' preference for rearing substrate Rearing substrate is an important component of the pre-weaning environment of dairy calves. Traditional substrate types, such as sawdust, are becoming difficult and/or expensive for farmers to obtain in New Zealand. Therefore, there is a need to evaluate alternative rearing substrates for dairy calves that that are economically viable for farmers, readily available and provide an acceptable level of animal welfare. The preference of dairy calves for four different rearing substrates and the effects on behaviour and physiology were evaluated. At 1 wk of age, 24 calves were housed in groups of four, in pens which were evenly divided into four rearing substrates: sawdust, rubber, sand and stones. During the first 3 d calves were given free access to all four substrates. Calves were then restricted to each substrate type for 48 h. In order to rank preference, calves were subsequently exposed to two surfaces simultaneously for 48 h until calves experienced all six treatment combinations. Finally, calves were given free access to all four substrates simultaneously for 48 h. Lying behaviour and location in the pen was recorded for 24 h at the end of each experimental period using handycams and accelerometers. Preference was determined based on lying times on each substrate. The insulating properties of each substrate were assessed using iButtons®. 
During the initial free choice period, the proportion of time spent standing (p < .001) and lying (p < .001) was influenced by substrate. Calves spent a higher proportion of time on sawdust (88%) than all other substrates (rubber: 6%, sand: 4% and stones: 3%). 
When restricted to each substrate, calves spent more (p <.05) time running on sawdust, rubber and sand compared to calves on stones. There were no effects (p > .05) of rearing substrate on the frequency of jumps, buck/kicks, head to object and mount/frontal pushing. Calves spent more (p < .05) time lying on sawdust and rubber in comparison to sand and stones. There were no effects (p > .05) of rearing substrate on the number and duration of lying bouts. We detected no effect (p > .05) of rearing substrate on concentrations of cortisol, lactate, glucose, or white blood cell, neutrophil and lymphocyte count or the neutrophil:lymphocyte ratio. The insulating properties were greatest for sawdust and lowest for sand.
During the pairwise choice period, calves had a strong preference for one substrate over another, spending on average, 89% of their time on the preferred surface. Calves preference ranking was for sawdust, rubber, sand then stones as determined by the proportion of time spent on each surface. At the end of the study, when given free access to all rearing substrates again, calves spent a higher proportion of time on sawdust (85%) than all other substrates (rubber: 5%, sand: 7% and stones: 3%). 
In conclusion, dairy calves showed a clear preference for sawdust over rubber, sand and stones. This preference remained consistent over the course of the study. The calves’ preference for sawdust may be associated with the physical and thermal properties in comparison to the alternative substrates. However, factors such as cost to the farmer, availability and practicality of alternative substrates need to be considered along with animal preferences before any recommendations can be made.

year: 2014

title: Māori language procreation on social media

authors: Keegan, Te Taka Adrian Gregory

abstract: The Māori language has taken seed and grown on social media. This presentation will examine this presence, exploring the forms it has taken and the influence it is having. It will look at Facebook groups devoted to the Māori language and the birth of the 'Māhuru Māori' (Māori September) movement. It will consider the increasing use of the Māori language on Twitter especially Tweets around a 'kaupapa' (shared purpose). It will also report some anecdotal evidence regarding the use of the Māori language on SnapChat, WhatsApp, and Messenger.

text: Māori language procreation on social media The Māori language has taken seed and grown on social media. This presentation will examine this presence, exploring the forms it has taken and the influence it is having. It will look at Facebook groups devoted to the Māori language and the birth of the 'Māhuru Māori' (Māori September) movement. It will consider the increasing use of the Māori language on Twitter especially Tweets around a 'kaupapa' (shared purpose). It will also report some anecdotal evidence regarding the use of the Māori language on SnapChat, WhatsApp, and Messenger.

year: 2019