I am excited to be reconnecting with my Japanese ‘roots’ by being part of this upcoming symposium thinking about the place of urban streams in Japanese cities, environment and culture.
First published on http://www.catherineknight.nz
Last weekend, we entered a time machine, which took us back in time about 18,000 years to a much colder version of the Manawatu – the last glaciation period. And we did this by walking just metres from our house. We were fortunate to have as our time-machine guide Professor of fluvial geomorphology Ian Fuller.
This bit of time travel solved a number of mysteries that had drawn on my curiosity for some time.
As I have described in previous posts, to access our gully stream, we walk down a spur from our paddocks (on a river terrace), with sheer drops on either side. The top of the spur is made up of a loose mix of soil and stones, the sort of material you would expect to see on a river flood plain. But the spur is 20 metres higher than the current streambed – could the stream at one time been a surging torrent so voluminous it had scattered river gravel across the spur?
With an expert at our disposal (not literally obviously – we are nice to our guests!), we discovered the more likely explanation. Our river terrace, now tens of metres above the Pohangina River, was once the flood plain of a braided river, bringing huge quantities of greywacke rock down from the ranges in its wandering currents. This braided river flowed during the glacial maximum – 18,000 to 20,000 years ago, when glaciers was last at their maximum extent, and otherwise known as the last glaciation. Aotearoa New Zealand was quite a bit bigger then, and joined up as one island (see this map) – which would have been handy if there had been any people around to enjoy the convenience!
As well as being a lot colder, the landscape was quite different then – instead of the dense forest that greeted our island’s first settlers 700 or so years ago, the landscape was a mosaic of grassland and shrubby plants, with patches of beech and a few scattered conifers. See vegetation map from Newnham, Wilmhurst and McGlone (2013).
The second mystery that this bit of time travel solved was how a relatively small stream that can go dry in the summer months could have carved out such a cavernous gully of 20 metres depth. Well the answer, in very simple terms is this. As our islands started to warm after this last ‘cold snap’, the Pohangina River, which our stream is a tributary to, started to cut down into the soft mudstone land. As it did so, the stream also needed to cut down to keep up (or more accurately, down) with the river, probably through the gradual shifting of a waterfall into the river upstream, or, in fluvial geomorphologist language: ‘the mechanism was probably the headward retreat of a waterfall, initiated by incision of the main river’. … What I said.
The exciting thing is, we still have that waterfall, though it now comes out of a concrete culvert rather than a natural channel. It is likely that it cut back to this place, an area of particularly hard and stable rock, and because of its relative stability, engineers chose this place to build the road over the stream a century or so ago, piping it through a culvert. Thus, the waterfall has been ‘frozen’ in time, unable to cut back any more.
It is a daunting to have your work reviewed by someone as well respected in the field of environmental history as Graeme Wynn, Professor Emeritus in Geography, University of British Columbia. A relief to find it is a positive review, and an very nice indeed to read his assessment that “Catherine Knight is set fair to take her place among the country’s leading environmental historians”. Continue reading
Looking forward to this event this Thursday November 1, as part of Local History Week 2018.
I will be taking the audience on a journey of discovery of the Manawatu’s past through the photographs of C.E. Wildbore and others. The event also marks the launch of Totara Press’s beautiful new (French-flapped) edition of Ravaged Beauty: An environmental history.
Wildbore: A photographic legacy will also be for sale at the event.
See event details here
Forget about what Pixie thinks, Beyond Manapouri: 50 years of environmental politics in New Zealand has been short-listed for the New Zealand Heritage Book Awards, alongside some prestigious authors such as Dame Ann Salmond.
A paper exploring how the perception of rivers has changed over time has just been published in a special issue of the international journal River Research Applications, entitled The meaning of rivers in Aotearoa New Zealand – Past and present”.
This paper examines how attitudes towards rivers in Aotearoa New Zealand have
evolved since the country’s settlement by Europeans, two centuries ago. For most
of our postcolonial history, rivers have been viewed as something to be controlled
and managed—even “improved.” But today, rivers are increasingly being recognized
as embodying a broad range of values from the ecological to the spiritual—not simply
as a “channel of water” that can be exploited for human ends. Although much of this
evolving understanding stems from the advance in scientific knowledge, much too has
its roots in our collective past.
The paper can be viewed here: River Research Applications
Yes, the rumours are true! The sparkly new edition of “Ravaged Beauty: An environmental history of the Manawatu”, published by Totara Press, is now available! And it looks stunning. The French flaps are back by popular demand, the photographs are almost jumping off the page they look so good, and we have made a few design enhancements to make your reading experience all the more enjoyable.
But best of all? The price remains exactly the same, at $49.99.
The launch of “Wildbore: A photographic legacy” on Wednesday night was an amazing success, with over 80 people attending, including around 20 people from the wonderful Wildbore clan. Thank you all for coming along and making it such a successful and enjoyable event. Here are some photo highlights.
I was recently alerted to this interesting graph showing the various drivers in landscape transformation in Aotearoa New Zealand over the past two centuries. The graph appears in Eric Pawson’s chapter ‘Sustainability and management of the environment’ in The physical environment: A New Zealand perspective, edited by A. Sturman and R. Spronken-Smith (Oxford University Press, 2001). It would be an intriguing to see how the graph looks beyond 2000.