Week
6 Workshop
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Week
6 Workshop
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Humans
as Agents of Landscape Change:
This web page considers further the impact of humans within the landscape. This 'workshop' illustrates the impact of humans within the urban environment and reflects upon urban geomorphology.
Urban Geomorphology -some thoughts.
Why is this lecture part of the course? The course is entitled landscape development, and urban landscapes are the most rapidly evolving landscapes that we encounter. You will not find books that specifically deal with the subject. You will find books that are relevant: Geomorphology in Environmental Planning (Hooke,1988); Geomorphology in Environmental Management (Cooke and Doornkamp, 1990, 2nd. edn), Human Impact on the Natural environment (Goudie, 1990, 3rd edn); The Human Impact Reader (Goudie, 1997) and The Earth Transformed (Goudie and Viles, 1997) to name but a few; but these books and other articles or book chapters all illustrate the problem identified by Slaymaker and Spencer (1999), which I outlined at the beginning of my section of the course.
The problem is that the focus of urban geomorphological study is upon processes which are artificially divorced from each other by the nature of the academic discipline. Thus human impacts upon fluvial systems are considered in isolation from other impacts, yet there is often overlap with other areas, such weathering or erosion. Sometimes the divorce is spatial: Urban Geomorphology in Drylands (Cooke et. al. 1983) exemplifies an example of a limited spatial scope. A physical geography of urban environments is distinctly lacking in the literature. This web page therefore contributes a start to the task of filling the gap. In the nature of these things all that I can do is highlight some issues as exemplified by Stoke-on-Trent, but as the issues will illustrate, there is a role for urban geomorphologists.
What is the urban landscape?
I do not wish to get into debates concerning definitions of 'rural' and 'urban'. For the purposes of this lecture the urban environment is equated with landscapes where non-agricultural industrial activity takes place, and where two or more dwellings where people live occur. OK, it's not brilliant, but can you strictly define the urban and rural?
Take
my house for example. Where does the rural end and the urban begin? So far as
I am concerned it is at the fence that the boundary is found. In terms of urban
geomorphology the case for urbanisation beginning at the fence can be strongly
made. (More later). On this side of the fence the farmland constitutes the rural
landscape: it is affected by human activity, but in rather different ways to
the urban environment beyond the fence. Beyond the fence different kinds of
economic uses of the land have very different consequences within the landscape
as compared to agricultural activity (in all of its forms).
In order to illustrate a number of issues in urban geomorphology I will adopt two strategies. Firstly I will use examples from the Biddulph Valley in North Staffordshire to illustrate some rather obvious matters, and then I will consider Stoke-on-Trent.
Using Biddulph as an example is justified on two counts; firstly it does provide an interesting and manageable case study, secondly I live there and know a bit more about Biddulph than elsewhere. So there. When considering issues in Stoke I will look at a number of issues: the fluvial environment, constructive landforms and issues and excavated landforms and issues. These are broad themes, but the linkages between them are obvious - for example excavation in one place undoubtedly leads to accumulation in another. The spatial and temporal impacts of the human activity that leads to excavation or construction may vary markedly. As we shall see...
Biddulph Valley.
The issues in the Biddulph Valley are not unique, but provide a manageable starting point. You should all be familiar with the area, as none of you skived off the field course around North Staffs at the beginning of the first year, did you? Good. But just in case the clickable image below will act as a reminder.
As you pan from left to right in the movie the dominant feature is the hill on the far side of the valley. This is Biddulph Moor and Lask Edge. At the far left (northern) extremity is a hill called The Cloud. The darker colour of the vegetation reflects typical moorland vegetation of Ling (called Heather in Scotland, Calluna vulgaris) and Bracken. This area of Biddulph Moor was certainly occupied during the Bronze Age, and may well be a relict element of Mesolithic activity.
As you pan right the largely agricultural landscape is replaced by the town of Biddulph on the valley floor. The town owes its current existence to its industrial heritage: a heritage at least 1000 years old. Farming of itself has always been marginal in this area of the Pennines, and so local inhabitants have always supplemented their income from agriculture by mining for coal and iron, both of which outcrop close to the surface in Biddulph; and by smelting iron and manufacturing pottery (bands of marls also outcrop locally). As can be imagined, the combination of resources enabled the activities to complement each other. Thus Biddulph has always been an industrial valley capable of supporting a large population. The 1791 census revealed that 2000 people lived in the parish of Biddulph - compare that with only 200 living in Tunstall at the time.
It
was only in the 19th century that new industries such as textiles moved into
the valley to exploit the abundant local labour supply, as well the energy of
the streams in this area of high relief and abundant water. (Believe me, it
is very damp in Biddulph). This was part of the process of specialisation and
concentration of capital which is what the 'Industrial Revolution' was really
about. The industrial revolution is exemplified as you pan south (right) of
the town. The collection of larger, rather ugly and obviously industrial buildings
are all that remains of what was once Knypersley Victoria colliery. To the extreme
right you can see the preserved buildings of the much larger Chatterley Whitfield
colliery, and its associated spoil tip (tip bank).
Above:the
dark vegetated mound in the middle of
the
picture is the tailings of a small 17th century mineworking
The presence of large collieries in the valley eventually led to an expansion of the urban environment - as is often the case with industry. By 1931 there were 6,000 people in Biddulph. The major growth in the urbanised area of Biddulph has, however, been since the war, mostly since 1960. There are now some 22,000 people living in Biddulph. The expansion of dwellings has been the major geomorphological change within the landscape, but industry has had an impact too. Let us now consider these impacts.
The site of the former Victoria colliery is now completely transformed. After closure in 1984 the site of the colliery was worked as an opencast operation up until the mid 1990s. The colliery was formerly known as the Biddulph Valley Coal and Ironworks, and during the opencasting operation the blast furnaces of the bar iron works came to light. When the ironworks was operational (early 1920s) it was the largest producer of bar iron in the world. Unfortunately nobody wanted bar iron - steel was much more useful. I only mention this to give you some idea of the sheer size of the opencast operation - the blast furnace foundations were only uncovered during the last 6 months of opencast working. The geography division has aerial photos of the site in 1993 - dig out a stereo pair and look - the hole in the ground was enormous. Look at it now:
After extraction came reclamation. The image above shows a small area of the infilled workings. The top-soil provides a meagre sustenance for poor quality vegetation. The land has been returned to agricultural use, (a few mangey sheep that will eat anything) but there may be problems ahead. Made ground such as this is very susceptible, as we shall see. Unused colliery waste was used to infill the land, and may be considered preferable to the other options available. The other options are mentioned below.
The photo above was taken from the edge of a small opencast operation that ceased working last year (1999) and was only begun in 1997 (I think). Image below, left:
This
small enterprise in Brindley Ford, near Biddulph, has left a very different
morphological legacy. The hole you see is not visible from any road, house or
viewpoint and thus there may be no need to re-create a new environment. It could
not be infilled as there is insufficient overburden to replace all of the removed
coal. The water body may appear to offer potential to wildlife, but this is
not likely. There is evidence of slumping and sedimentary infill, and spoil
tips such as these, due to deep penetration by water and mobilised regolith,
give rise to much higher concentrations of heavy metals within water bodies
than would otherwise be the case.
An alternative to scars in the landscape is to infill with them with refuse - an enormous by-product of urban living. Just across the road from the Brindley Ford workings, (in the opposite direction to the view in the photo, note Chatterley Whitfield in the background) is an older opencast working. Known as Bemersley tip, the site is now completely infilled with domestic waste, and does not make a good photo.
There
is a legacy here, too. The refuse is now decaying, and returning methane to
the atmosphere. Methane is a potentially dangerous, explosive gas, and emission
needs to be controlled. It is also an important greenhouse gas. The solution
to the problem posed by gas emission at Bemersley, as at many waste sites, is
to burn it. This converts methane into nice safe carbon dioxide, water vapour
and heat. So that's the environment looked after, then.
The three simple examples shown here illustrate some of the geomorphic impacts of certain kinds of industry. In fact their impacts are greater. I will have to wait until we have another good storm to illustrate their impacts upon water flow, for the roads around all three landfill (or not) areas are very prone to flooding, especially at Brindley Ford. The deeply disturbed and uncompacted fills promote rapid throughflow that regularly overwhelms local sewerage systems. Disturbingly deep floods can occur on the roads out of southern Biddulph at any time of the year, and so far the attempts to remediate flooding around the area have proven laughable. The presence of numerous 'dry' valleys (a Pleistocene legacy) would indicate that tinkering with surface drainage will not provide the answer, but who is going to listen to a geomorphologist, eh?
Industrial
impacts upon the landscape are not just in terms of new morphological features,
water flows and environmental chemistry. Visual impacts also cause concern.
The observant amongst you may have noticed a large pink scar on the side of
Biddulph moor as you panned south from The Cloud toward the north of Biddulph
in the VR movie. To save you going back, the image right shows it again. The
quarry extracts the extremely silica pure Westphalian sandstone that is found
in Biddulph. Sandstone from this quarry is used in quality glassware. The quarry
is also a terrible eyesore.
This brings me on to a point I wish to re-iterate from my first lecture. Slaymaker and Spencer (1999) have produced a new model in their paradigm for physical geography that argues that the concept of time and landscape change needs to be re-introduced to physical geography; but within a social, political and economic framework. The examples shown above, of economic and industrial exploitation of the landscape demonstrate how and why physical geography can and must re-engage with society.
Physical geographers have a lot to offer in terms of investigating and understanding the consequences of human alteration of landscapes. In Biddulph and other areas of the Staffordshire Moorlands there is intense pressure to exploit a wealth of mineral resources. This pressure is, in part, a consequence of the proximity of the area to the Peak District National Park; whose borders are a mere five miles distant over the moor. The resources of the national park are 'untouchable', therefore the resources of the immediately adjacent areas carry a premium. It is not just coal, holes and sandstone that attracts attention - there are gas reserves in the valley beyond Lask Edge, and water is an important resource too. Geomorphology must play its part in ensuring that activity appropriate to the long term development of the environment is undertaken. As physical geographers we are uniquely placed to consider the development of the environment - understanding landscape development is a fundamental component of our endeavour.
The built environment has a profound impact upon the landscape. The major impact is the sterilisation and desiccation of the land surface. Once built upon, land will not be restored to alternative use for many generations. In Biddulph there has been considerable pressure for land to be taken out of agriculture and turned over to the urban environment, and since 1950 a great deal of land has been transformed in this way. Most of the urban area you saw in the panorama can be divided into two housing estates; the miners' estate, a post-war coal-board built housing estate, and a younger, private development. I have just bought my second new house in Biddulph - and thus I find myself directly contributing toward landscape development in Biddulph. What impacts have I had?
For
one, take a look at the image, right. The hedge has been removed to create space
for my fence, (boooo!) It will be replaced,
honest! and you will observe a line of grey material within the
muddy area. This is a gravel drain, put in at my insistence. As the house was
being built an alarmingly large pond built up against an earth embankment where
my fence is, and eventually built up sufficient pressure to burst through the
bank and threaten to erode the concrete base of my house. This disturbed me.
The small valley leading to the fence appears dry, but interference with the natural drainage of the field recreated conditions for overland flow. The field is now drained through a culvert under my front garden. I should have known - the ground is very boggy- but it was too late by the time I twigged what was happening. In fact this field is one of the many sources of the River Mersey. (Which is ironic, for as a postgrad in Liverpool I lived by the banks of the Mersey, and now I live on the Mersey.... I don't think Scousers should be told).
The above was written in April 2000. In recent months (it now being Dec 2000) the problems created by new housing has featured prominently in the national media. It has also featured prominently in my front garden during the autumn. The culvert that was put in is too small, and cannot cope with the flow of water off the field. The foundations for my garage and house do not help - in times of heavy rain little springs suddenly emerge along the wall of my garage, and the manhole becomes completely overwhelmed (photos to arrive when they have been developed).
The deputy prime minister has declared that there will be a moratorium on new housing developments in vulnerable river floodplains. But as my little example clearly demonstrates, it is not just in the floodplains that there is a problem, proximity to the water table is also a problem. In this upper part of the Biddulph Brook catchment, a very large proportion of the upper catchment is urbanised, and natural drainage (and more importantly storage) is impeded by building.
The
interference with drainage is one of the major consequences of urbanisation.
The image left shows the potential. The new housing development sits upon a
network of 'dry' valleys. (One of them is a valley which crosses the Trent-Mersey
watershed, it's a former sub-glacial meltwater channel. Interesting, huh? It
gets me excited anyway). If you walk along the valleys, they don't seem so dry.
They are an important part of the upper drainage network of Biddulph Brook.
So what? says you. So this. Construction of a large amount of impermeable surface leads to increasingly rapid run-off within what is already a rather 'flashy' catchment. The small misfit stream of Biddulph Brook can come under considerable pressure during times of heavy rainfall, and becomes very prone to flooding. Biddulph Brook flows downstream of my house for about a mile, and is surrounded by urban landscapes. The only drainage route for water is via Biddulph Brook, and all that nice muddy, boggy, and sponge-like land has gone. The topography is relatively steep, too.
Bearing all this in mind, your next task is to choose a site for the location of a new leisure centre for the town.
In
1996 a new leisure centre was built in Biddulph, expanding the site where the
swimming baths were located. (It is pictured,
right). It was built slap-bang over Biddulph Brook, which is culverted
underneath the main Sports Hall and Squash courts. The culvert is more than
sufficient to cope with normal drainage, and even bankful drainage. We know,
'cos those clever engineers with their super-duper flow models say so. The problem
is, Biddulph Brook has an alarming tendency to burst its banks. Consequently,
the floor of the Leisure centre has now been entirely replaced, twice, since
it was built. If only they had talked to a geographer... To date, nobody in
the planning or engineering departments of Staffordshire Moorlands District
Council has been shot. No-one knows why.
Nothing in the foregoing is especially unique to Biddulph, many problems and features illustrated can be found in any urban environment, but on different scales. There is one unique site of landscape change in Biddulph, and it can be can be found at Biddulph Grange - it is worth a visit. The landscape change was effected by James Bateman, one time owner of Biddulph Coal and Ironworks. His gardens at Biddulph were created to reflect the whole world. There are different sections within the garden - a Chinese garden, an Italianate garden, an Egyptian garden and a Scottish glen, to name but a few. A large area of northern Biddulph is also a product of his imagination - a recreated 'natural' Staffordshire landscape.
But enough of Biddulph.
Urban geomorphology in Stoke-on-Trent.
I will now consider specific aspects of the urban landscape of Stoke. I will look at constructed, excavated and fluvial elements of the landscape, and some of their linkages. For a start, the overall picture. Below is a 360-degrees panorama:-
The movie is not brilliant, but some of the major features are evident. The image was taken from the site of the former Park Hall Quarry. This country park shows another potential means of reclaiming land, as a recreational leisure site for walking or golf. (Mark Twain suggested that golf was just a means of spoiling a good walk...). Obvious features within the panorama are the Trent valley (the low bit), the tall buildings, especially around Hanley (the high bit) and the tip banks (the blurry tall bumpy bits). The human impact upon the landscape is evident at a variety of scales.
Extraction and its impacts.
Stoke
has been dug over, under
and sideways for generations. The most important resources have been coal
and clay. Clay (marl) pits were once a profound feature of the environment of
Stoke-on-Trent. Many have now been reclaimed and landscaped, a few have been
infilled. One of the last remaining unlandscaped pits is Fenton Manor, left.
A great deal of remedial work needs to be undertaken to bring this land back
into human use. The possibilities are not great, but it may be possible, say,
to build student halls of residence on the site, for example. (You think I'm
joking...)
Areas
such as this in the urban landscape can yield surprises: who'd have thought
bulrushes would find a haven here...(right)
.
Beyond the visual impact, the effects of excavations such as this may seem trivial, but they can have consequences beyond the immediate, in terms of both time and space.
The
excavation (right) is an activeeconomic
concern. Etruria marl is excavated for use in cement making (in Buxton) and
in local earthenware production. The site may not be pretty, but its location
near Longport can hardly be considered detrimental, given the aesthetics of
the rest of the environment. The machinery you see in the photograph is not
being used to extract the clay, but to enable access to the clay. The excavators
are dealing with a legacy of former extraction.
In the woodlands above the quarry are tailings from older extractive industry. Water flow through these spoil tips is accelerated. Not only is water flow enhanced, but sediment is more mobile. Prior to renewed extraction of clay, it was known that water flow was a problem, and a drainage ditch was emplaced on the hillside.
Unfortunately
the ditch is now infilled, and thus water flow over, and into the clay beds
is enhanced. The combination of increased pore water pressure and undercutting
of the quarry face has lead to considerable slope instability. As a consequence,
the quarry operators are engaged in a battle, annually after every winter, to
remove slumped and failed talus from the foot of the quarry face in order that
the source of their economic likelihood can be accessed. The evidence of slump
and flow is obvious in the photograph. Ironically, the upper yellow marl is
used by the waterboard to waterproof canals!
| I wish to express gratitude to Kimberley and Sons for their kind permission to access and photograph the site, and their informative discussion concerning their work. |
The
other major extractive industry in Stoke was, of course, coal. Chatterley-Whitfield
colliery is preserved as a reminder of this once fundamental industry within
the local economy (right and left). Coal
mining has now ceased altogether within the area, but the legacy remains.
A major visible legacy of extraction is that of subsidence. The removal of thousands of tons of coal from the subsurface causes the settlement of land. The consequence of subsidence in rural areas is marginal, but in the urban environment it is enormous. Modern building techniques can accommodate subsidence (supposedly), but older buildings are particularly prone.
The
example of Cobridge church and vicarage illustrate the point well. The church
is suffering due to a combination of poor construction and settlement caused
by coal extraction from Hanley Deep, Sneyd and Wolstanton collieries. The most
serious impact is depicted left. There is considerable evidence of repointing
and re-roofing yet still the wall of this annexe is falling away from the main
body of the church, and now needs support from a timber frame. How long or effective
this support will be is open to debate... (update 2001 - extensive repairs have
now been undertaken at the church).
The vicarage has similarly suffered over the years. There are many clues as to the effects of subsidence upon the vicarage. How many can you spot? See the image below.
The problem of subsidence due to mining is not unique to Burslem, Stoke or even the UK. The problem is widespread expensive and sometimes life threatening. New brickwork, different tiles, repointed roof and a wobbly roofline in the picture indicate a continuing problem.
Some consequences, however,are most unpredictable. Take Westport Lake, for example:
This
pleasant area of Burslem formed as a consequence of subsidence at the beginning
of this century. It is now an urban park, and haven for local wildlife. It was
rather impoverished until reclamation of the site from the waste of surrounding
industry, but it is not bad as an amenity. God bless the coal board!
Humans
create all sorts of landforms. These constructional landforms are themselves
an integral part of our evolving landscape, they lead to the development of
new landforms and become subject to the processes of natural decay over time.
The landforms are just less able to resist, that's all. Just look at the photo
of Cobridge vicarage wall, left. The cement is nothing like as resistant as
the matrix of your average clastic sedimentary Palaeozoic rock, and the clasts
(bricks) are becoming severely weathered by frost action. It is not just physical
weathering that gets to work on your masonry. Chemical weathering is advanced
too.
This
church in Tunstall (left) shows the effects
of chemical weathering of sandstone, as does Burslem town hall (right).
But less resistant lithologies are even more prone to chemical attack (below).
I do not know a great deal about the subject of building stone decay, but Janet
does. You can learn a lot more in her 'applied weathering' course at level 3.
What I do know is that modern increases in sulphur levels, particularly caused
by cars, does not help.
Shops, Burslem. 
 |
The most striking constructional landforms that dominate the Stoke skyline are the tip banks. These huge mounds of material consist of more debris than that deposited by the last glaciers in the area, apparently, (Derbyshire, 1995). The tip banks are the most obvious by-product of coal-mining, and the most difficult to landscape. By-and-large they have been left as they were. They are moderately landscaped and incorporated into reclaimed areas of leisure within the city. Attempts to totally rehabilitate these tips are hindered on two counts. |
|
Above: tip bank, Sneyd. |
Firstly,
as mentioned earlier, spoil tips are likely to have higher concentrations of
mobile and toxic heavy metals. Whilst there is some evidence of colonisation
of the tip banks by trees and other flora, the colonisers are specialists. The
tip banks are covered by thin soils, and the colonisers are those whose roots
are not deep. The thinness of the soils is one factor, but those plants that
have deep, penetrating root networks would soon come into contact with high
concentrations of toxic heavy metals, and cannot survive.
Secondly,
as deep soils will not develop, the sediments of the tip banks are very erodible.
What we as humans are unwilling to do, nature is beginning to do anyway. The
evidence of rilling and gullying on the steep sides of the tip banks of Central
Forest Park and Sneyd hill, for example, suggest that they will one day be reduced
to insignificant mounds in the landscape of Stoke-on-Trent.
A different constructional landform is the landfill site. We have seen examples in Biddulph, but there are many examples in Stoke. Many sites have been reclaimed for development, some are still to be completely infilled, whilst others are left as green spaces within the city.
The Greenway project can be viewed as another type of reclamational landform - it alters former constructed routeways to increase the amount of green-space, and non-motorised traffic transport links, within the urban environment.
I
have already illustrated certain impacts on fluvial systems that are consequent
upon the construction of urban environments. Not much more needs to be said.
Rivers are naughty, unpredictable swines that need to be strictly governed;
if not they will misbehave. Take the river Trent (right).
It flows gently through Stoke, but its regime is controlled. The banks of the
river need to be managed, and the young river is not allowed to have any botanical
friends to stay. If plants do colonise the bed, flow patterns will alter and
it will begin to migrate around obstacles. The halls of residence in the picture
might then become threatened.
It
is not just the channel that needs management, the flow of the river needs regulating.
The source of the Trent is on Biddulph Moor, (oh, these clever continuities),
and just below the Moor at Knypersley, the Head of the Trent has been controlled
since the Tudor period (and was even mentioned by Shakespeare). Since the last
century Knypersley pool has helped control the flow of water in the upper Trent,
(right) although its main purpose is to
store water for the Cauldon canal. (Below)
By controlling the natural river, humans have to become engaged in the maintenance of the river system, since many of the natural means of adapted to continuing environmental change are no longer available to the river.
The
problem of waterway management is even greater in artificial waterways (canals).
I think canals are great, but they are difficult to maintain. Since they do
not rely upon their own catchments for water supply, but borrow from natural
catchments, canals actually increase the premium of that most basic of commodities
we take for granted: water. The volume of water within canals must be maintained
at a constant level if they are to function. Therefore canals need to be watertight
(thankfully Stoke has naturally occurring waterproofing materials, see above).
Canals must also not flow - this reduces the demand for water. Typical discharge
at any point on a canal is zero, except at rare points in time through lock
gates.
Therefore water is lost from canals, and needs to be replenished from natural fluvial systems. In times of drought canals cannot be run down - this exposes the banks to sub-aerial weathering and erosion, which would be disastrous. Consequently already deprived natural waterways have their flows even further reduced in order to maintain artificial waterways, and landscape desiccation is enhanced. In the summer of 1995 Knypersley pool was virtually drained in order to maintain Cauldon Canal. Thus modern urban living, in a variety of ways, dries out the environment. The management of waterways since the eighteenth century has had enormous impact upon the the natural water cycle in Britain - water meadows have all but disappeared. And, of course, canals can never be allowed to flood. The river systems that canals depend upon must of necessity be managed in order that canals function. Hence the curious juxtaposition below:
Above: The diversion of
the river Trent
beneath Stoke canal (No neeeed!).
Below:Stoke
Canal. Luvverley
.
The geomorphology of urban environments is complex and rapidly evolving. Processes initiated by human intervention in the environment are not isolated, but inter-linked with other processes and the wider environment. The linkages between different processes is not widely discussed in the literature, and in social, political and economic contexts, problems that are perceived to arise as a consequence of singular events or circumstance are dealt with in a rather haphazard manner.
The application of geomorphological study to the urban environment is often viewed as a particular dimension of geography encompassed by the term 'applied geography'. Geographers tend to study certain process related phenomena in isolation with regard to the urban environment, without regard to wider spatial and temporal linkages. There is room for an urban geography that adopts a more holistic, non-applied (commercial) approach that will better enable a more complete understanding of new, rapidly changing environments.
Consider once more the environment of Stoke (image below), and you may be able to think of potential third year projects, should your current musings amount to naught. Sorry, too florid. It is 2.00a.m. and cognitive and intellectual processes go hay-wire about now.
Finally, ask yourselves the following questions (you could even write an essay for the hell of it):
1. What potential role has geomorphology to play with regard to the future development of human environments?
2. Would you like to be employed as a consultant geomorphologist?
That's all folks.