Hackfall can be found on the south bank of the River Ure as it weaves its way from Masham southeast towards the city of Ripon. This stretch of woodland lies on the outskirts of the village of Grewelthorpe, bordering the rolling farmland which slopes off gradually to the north over Nutwith Common. The eastern edge of this farmland is the steep escarpment on which Hackfall is situated.
The composition of the escarpment is in several distinct layers. The glacial till of the farmland lies on top of a strong sandstone layer known as Lower Brimham Grit, which is visible in places along the edge.
Below this gritstone is a series of weaker rocks which have been weathered away over time to form a steep slope of shales, mudstones and sandstones. The topmost soft layer is the Ure Shell Bed, which is rich in marine fossils, and was described in the Proceedings of the Yorkshire Geological Society 1965 as "a grey siltstone composed of clastic quartz, flakes of muscovite, biotite and chlorite."
Under the Ure Shell Bed is the Cayton Gill Shell Bed, a loose agglomeration of mudstones which is several metres thick and also rich in fossils. The Cayton Gill Shell Bed was first recorded on geological maps at this very spot. The British Geological Survey describe this bed as "silty mudstone, calcareous and silicaceous, shelly with beds of siltstone and sandstone."
As the wet Yorkshire weather and the movement of the River Ure below have washed away this loose material, boulders from the upper gritstone layer have come down the slope and can be found at the base, around the area of the river bed. This part of the slope is composed of Libishaw Sandstone, a typically brown and fine-grained rock with a mottled appearance due to kaolinized feldspars.
One of the most striking geological features of Hackfall is the plentiful supply of Tufa, which has been extruded in a number of spots around Hackfall. How the Tufa came to be here is not clear, as there are no known bands of limestone within the shale beds here, however it may be indicative of as yet unknown thin limestone bands within the shale, or limestone debris in the glacial till at the top of the slope. You'll need to look further into how the Tufa was produced (see below).
The Tufa was used in Lime Kilns near the river and there was also a thin coal seam below the Ure Shell Bed, which was mined locally on a small scale.
As you can see, the geology of Hackfall is a reason to visit here and the steep slope appears in places to be entirely natural, but the thing that makes the woods unique is that they are not a wholly natural feature after all, but have rather been landscaped to enhance what nature had already provided...
It is a quiet and little known location today, however back in the eighteenth and nineteenth centuries Hackfall was considered one of the most beautiful places in Europe, attracting creative spirits to write, paint and extemporise within the carefully created gardens.
Originally planned as a man-made wilderness by John Aislabie, the genius behind the landscaping at Fountains Abbey and Studley Royal, Hackfall grew and developed in character thanks to John's son William who, as well as being MP for Ripon for 60 years, also arranged for the building of a number of follies and the enhancement of some natural features within Hackfall Wood.
The heyday of the woodland gardens was the nineteenth century. William Wordsworth mentioned Hackfall as a place to visit on the way to the Lake District through Yorkshire and J M W Turner is known to have visited the woods and painted them. Wealthy gentlemen on the European Tour would flock here to discover the carefully crafted grandeur of the woods and the riverside.
Unfortunately Hackfall then went through a period of decline and in the 1930s many of the mature trees were harvested. The follies began to crumble and the water features silted up and it seemed the wood would be lost forever. However the Woodland Trust and the Hackfall Trust stepped in, taking over the running of the woodland in the 1980s with a comprehensive programme of restoration. This culminated in a £1 million grant from the Heritage Lottery Fund in 2007. Not only have the natural features of the wood been restored, but also the follies and grottoes. These unusual heritage features are ideally situated to provide added interest at attractive locations in the woods, from the peaceful dampness of Kent's Seat at the Alum Spring to the mock-medieval grandeur of Mowbray Castle, peeping through the trees as you explore the wood. One of the success stories of the restoration is the hugely impressive fountain which shoots water 30ft into the air, thanks to a cunningly disguised header tank at the top of the gorge! This fountain last worked circa 1810 and was a feature of William Aislabie's original gardens.
Hackfall is unique, and has been named both a Grade I Listed Garden and a Site of Special Scientific Interest. This highlights the unusual nature of the woods - they are natural woods which were turned into a wilderness garden, only to be reclaimed by nature and then restored to their previous man-made glory. They are also an important habitat for wild flowers, birds, bats, moths and other insects. Even on the walk down the hill from the car park it is possible to encounter over a dozen types of wild flower before reaching the first gate!
Work is still ongoing at Hackfall, but it provides an interesting spot for a walk as well as a good place to study the geology, flora and fauna of a northern English semi-natural broadleaf woodland. With this in mind, anyone wishing to log this earthcache must contact me with the answers to the following Tufa-related questions:
1) How is Tufa formed?
2) Why is there Tufa in Hackfall Wood? (There are several competing theories, so please give your reasons why you think there is Tufa here!)
3) What semi-natural feature can best be viewed from the Grotto, a folly built entirely from Tufa?
I would also like you to post a photo of yourself and/OR your gps at any one of the follies, water features or ruins within the wood.
I hope you enjoy your visit to Hackfall Woods. You'll find a nice new car park with an information board at the coordinates for this cache, from which the woods are a short stroll downhill. You could alternatively enter the woods along the Ripon Rowel Trail or from Grewelthorpe village itself. Please take your litter home with you, keep your dogs under close control (there are fields of livestock near the car park) and leave nothing there but footprints!
More information can be found at the Hackfall Trust website and via the Woodland Trust website.
You will find maps and educational materials at www.woodlandtrust.org.uk/hackfalldownloads