NW Highlands - Deep Time

In a human lifetime the North Atlantic will have widened by about 2 metres, the ongoing collision of the Indian plate with the the Eurasian plate will have increased the height of Nanga Parbat by 60 - 80 cm and a similar rise in land surface will occur near Hudson Bay, as the Earth's crust is still rebounding from the melting of the North American Ice Sheet. With a few interesting exceptions, geological processes in terms of human perception are generally slow paced affairs and a fundamental concept in geology is geological time or Deep Time. The first scientific attempts at dating the earth, involved cooling rates, seawater salinity and sedimentation rates, that resulted in calculated ages ranging from 24 to 400 million years. Whereas there is some familiarity with figures of millions and billions expressed in monetary and financial terms, many people can picture a 100 pounds/euros/dollars be it coinage or notes, few people will ever become centenarians and experience 100 years of time. To most people a million years is not an intuitive length of time. Even when reduced to seconds, a million seconds equates to just under 12 days. The Earth's age as quoted in textbooks towards the end of the 19th C was 100 million years, which seems a great length of time, but some geologists and naturalists thought it too short.

View of the Billion year old Torridonian / Lewisian nonconformity on the NE spur of A' Mhaighdean

In 1891 the discovery in the NW Highlands of Olenellus fossils in the Fucoid beds of the Saltera Grits formation, finally determined their position in the stratigraphic column as lower Cambrian in age. The fossil discovery again changed the geological history of the rocks in the NW Highlands, as the underlying Torridonian sedimentary rocks were relegated from their presumed Cambrian age and down into the Precambrian. The angular unconformity between the newly assigned Cambrian rocks with the underlying Torridonian, showed compelling evidence that the Torridonian were some way down into the Precambrian too. The Cambrian sedimentary rocks were deposited on a planation surface that had eroded away the Torridonian rock and also an unknown thickness of the underlying rocks of the Lewisian complex. Which implies there had been a long period of erosion and before that a long period of time to deposit the thick pile of Torridonian sediments. The Torridonian sediments are deposited on rocks of the Lewisian Complex and on a palaeo land surface with over 600m of relief between hill summits, valleys, cliffs and a surface covered with weathering debris. This presented another long period of time. Then there were the rocks of the Lewisian Complex, whose very nature implied a long and rich geological history.

The Torridonian inselberg Suilven rising above the Lewisian.

Amongst the many achievements of the Geological Surveys work in the North West Highlands in the closing decades of the 19th C, a notable one was the elucidation that the rocks outcropping in the NW Highlands were a window into the depths of Deep Time and a point emphasised on more than one occasion in the Geology Memoir 'The Geological Structure of the North West Highlands of Scotland" published 1907.

Coincidentally in 1907 the chemist Bertram Boltwood in a pioneering example of geophysics used the then estimate of the radioactive decay rate of uranium into lead, to measure the ratio of lead and uranium from some rocks and determined ages of 400 million - 2,200 million years. It is reasonable to suggest the ages were the subject of some controversy with some prominent geologists and Boltwood's interest in geological dating then waned. The challenge of dating rocks through radioactive decay was taken up by Arthur Holmes, it is difficult to challenge the hard science of physics and the geological community then set about ordering the rocks into the timeline of Earth's history. Dating of rocks has become ever more sophisticated and innovative, currently the Torridonian rocks have been dated to between 1.2 and 0.95 billion years old. It is worth stating that a billion seconds equates to a few months short of 32 years, a billion years is a vast stretch of time.

The Lewisian complex comprises rocks with an age spread from 1.6 to 3.0 Billion years, confirming their place in the depths of Deep Time.

Picturesque vs photogenic views - Lower Wye Valley, Autumn 2015

In the 18th C the Wye Tour was a popular tourist attraction, essentially a boat trip downriver with stopping off points on the journey, to stretch the legs and take in the views. The picturesque status of the Lower Wye Valley scenery was sealed with the publication in 1782 of William Gilpin's "Observations on the River Wye, and Several Parts of South Wales, Relative Chiefly to Picturesque Beauty; Made in the Summer of the Year 1770". In more recent times the Lower Wye Valley has been designated an Area of Outstanding Natural Beauty and much of the native woodland designated a Special Area of Conservation. So, in theory, the Lower Wye valley should present no shortage of photography opportunities. In practice the Lower Wye Valley presents some challenges in photographing the scenery. The challenges to photography manifest themselves in the absence of the Lower Wye Valley as a destination on the landscape photography workshop circuit and neither do many landscape photographers portfolios or galleries feature images of the Lower Wye Valley. If they do, they tend to be from one of the signposted viewpoints that are regularly cleared of trees and foliage to provide unobstructed views.

Picturesque the Lower Wye Valley is without doubt, however its photogenic qualities are compromised by the very same trees and foliage that add so much to the scenery and sadly obstruct many views. Then there are; access restrictions; intensively cultivated fields; power lines; topography and conservation activities. Whilst the clear felling and restoration of planted ancient woodland sites (PAWS) and the return of coppicing, are positive conservation activities, their initial visual impact is not the best. It really does pay to scout the location shortly before photographing it, as it is surprising how quickly modern forestry operations are executed, the only time of stability is in the bird nesting season when cessation of forestry activities occurs.

From my own perspective, the novelty of making derivative images from the viewpoints soon wore off and venturing away from the viewpoints has been a long learning curve and more than once I've questioned if there's an inverse relationship between picturesque and photogenic scenery.

A primary aesthetic of the views overlooking the Wye valley is the perspective on the woodland. Ancient semi natural woodland with a diverse canopy and patchwork of colour. The colours are there in spring, but shades of green are no match for autumn, where the trees express their individuality through a colour palette that varies from vermilion, amber, russet and yellows.

Two dawn trips and one was rewarded with a magenta sky over a mist filled valley, long neglected hedegrows provided a lead in, to be honest I was hoping for a lot less mist in the valley and a different view.

The weather then deteriorated with days of fog and then the jet stream notable by its absence, returned with a vengeance, streaming low pressure systems over the UK for days on end, effectively ending autumnal interest until next year, when the challenge can again be resumed.

On average a hectare of woodland produces 5 tonnes of organic debris per annum.

I asked myself the simple question - What is the weight of leaf litter produced by deciduous woodland? An almost unhealthy amount of google searches later and I am still none the wiser, there is no simple answer it seems.

Coarse woody debris

In the course of my search I did come across numbers for the organic debris generated by broadleaf woodland. Again there's no specific number, it depends on the nature of the woodland, the age of trees and a multitude of other factors. Organic debris encompasses the shedding of overtopped branches, leaf fall, seed casings, wind thrown branches, fallen trees, snags etc. There are figures published for the organic debris produced annually for a hectare of woodland ranging from a high of 25 t/yr down to a low of 2 t/yr, several sources settle on a hectare of broadleaved woodland producing 5 t/yr as a reasonable average figure for the organic debris produced.

Black bulgar (bulgaria inquinans)

I also discovered the ecological importance of organic debris in providing a habitat for a surprisingly large number of invertebrates, bryophytes and fungi, in short the biodiversity of a wood is proportional to the quantity of organic debris, age of the wood and trees within it. Veteran trees with their associated deadwood play host to a number of rare species,

The Shaden Tuft oak

Within the Churchill Inclosure in the Forest of Dean, there stands a large pollarded oak, it has been named the Shaden Tuft oak and unusually for a woodland tree, has been assigned a fairly precise planting date of 1599 and has been used as an example for dating of veteran and ancient trees in a Forestry Commission report. In an historical context, at the time of the oaks planting, Queen Elizabeth I was the reigning monarch and William Shakespeare was putting quill to ink and writing some of the finest works in the English language. The tree has also withstood some remarkable weather - great storms, droughts and the cold of the 'little ice age'.

Shaden Tuft oak

If the pollarding of the Shaden Tuft oak wasn't the result of storm breakage, then it hints at the possible woodland management regime at the time and the pollarding has probably ensured its continued presence, overlooked by Royal Navy shipwrights and then successive generations of timber merchants. Whilst not being particularly notable for its age - it is entering the oak equivalence of middle age - and all being well, should witness the events of the 26th C unfold.

I have wandered past this tree, I guess on average a couple of times a year for well over a decade and its presence gives continuity to the woodland and a tangible link to the past. There's something about old trees that provides a wood with a certain je ne sais quoi and I am no doubt that the woodland would be a poorer place in the absence of the older trees.

A different view of the woods

This year has been a vintage year for bracken growth in the Forest of Dean, in some parts the bracken stands well over head height, so without a step ladder and access to a 10' high tripod, the height of the bracken has proved compositionally challenging. It is also a mast year for acorns from some oaks and the resident wild boar population have 'ploughed' the woodland floor foraging for acorns, posing another compositional problem.

Taking a pragmatic approach, it seems sensible to eliminate the woodland floor entirely and use the topography to concentrate on perspectives of the woodland canopy.  It is reasonable to suggest that a woodland canopy is a visually complex environment, the architecture of the tree crowns, leaf densities and colours are the elements to draw inspiration from.

The tree crowns reveals the intense competition for access to sunlight and ultimately survival of the tree. The contrast between pure oak stands and mixed oak/beech trees, illustrates why planting beech with oak is desirable for premium grade timber. The time honoured approach of planting beech and oak in the ratio of 2:1 by the Deans foresters, was ignored by the early 19th C foresters who replanted the Dean, who employed a new approach for raising an oak forest covering ~11,000 acres and millions of trees. It was one of the more significant mistakes made in that exercise.