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FIELD GUIDE South Dorset Ridgeway This guide and accompanying maps have been produced by Dorset based artist Amanda FIELD GUIDE Wallwork. Amanda describes South Dorset Ridgeway herself as “primarily a painter, my practice is concerned with archaeology, geology and a continuing enquiry into CONTENTS landscape.” Introduction Amanda was commissioned The South Dorset Ridgeway to undertake this work by the Deep Time South Dorset Ridgeway The rocks of the Ridgeway and the Landscape Partnership signs to look out for Scheme. This Scheme is led by the Dorset Area of Habitats Outstanding Natural Beauty How rocks determine the soil, plants (Dorset AONB) and is and wildlife supported by the Heritage Earthworks Lottery Fund. Arts Council The shaping of this landscape by England has supported the prehistoric peoples - barrows, stone engagement of artists in this circles, henges and hillforts project. The Old Ways The Dorset AONB is one of Lines in the landscape - roads, a family of protected tracks, pathways and boundaries landscapes in the UK, working to conserve and enhance the Names natural beauty of these How names tell a landscape story special landscapes. and glossary of meanings The South Dorset Ridgeway area is defined by a THE world-class ceremonial landscape bearing the marks of continuous human occupation through SOUTH DORSET 6,000 years to the present day. It holds an incomparable density of Bronze Age round RIDGEWAY barrows - the single most defining feature - but is also home to Neolithic henges, spectacular Iron Age hillforts, Roman villas and defence sites, Celtic field systems and Medieval villages. The varied and detailed geology of the South Dorset Ridgeway means there is a remarkable diversity of habitats in a relatively small area. Combine this with the geographical location; Dorset is at a juncture between the ranges of northern Arctic species and southern Mediterranean species creating a hotspot of wildlife richness that the South Dorset Ridgeway runs right through. It is a farmed landscape now; it has been a farmed landscape for 6,000 years. The agricultural landscape is characterised by open arable and grassland fields on the shallower slopes bordered by hedges or stone walls, ribbons of semi-natural grassland on the steeper slopes and pockets of woodland. The South Dorset Ridgeway provides an introduction to the best that the British countryside has to offer. This guide and accompanying maps aim to help you explore and better understand this fascinating landscape. further down you go. However, DEEP TIME earth movements have Rocks of the Ridgeway interfered with this logical Geology underpins everything about our sequence - lifting, tilting and landscape yet the rocks below our feet are exposing older rocks to the largely hidden, and the natural processes that surface, subjecting them to have shaped the land operate on timescales erosion and further deposition that we find difficult to imagine. It is these and altering the sequence in rocks that have determined the landscape we places. see today - they in turn formed from previous The result is a land surface of landscapes millions of years ago. many differing types of rock. Each with its own properties “Viewed in cuttings and old quarries, which dictate how it behaves as rocks are the physical manifestations a material and influencing the shape of the landforms and of ancient worlds - shallow seas, formation of the soil and the shelly beaches and sticky swamps, habitats it supports. green forests and quiet lagoons.” And so the cycle continues - the creatures, plants, processes, Sam Scriven landscapes of the past making The rocks are sedimentary, formed over a the rocks that in turn make the span of 125 million years, mostly when this soil to support plant and animal area was underwater - a series of shallow life. All, in time, becoming part seas, lagoons and swamps. Formed from of the next layer of deposition. particles of other rocks and of decaying life, Whilst much of the geology is gradually accumulating in layers and slowly unseen, the Ridgeway landscape compressed, each one encapsulates a record offers visual clues to what’s of the environment at the time of its beneath and presents plenty of deposition. opportunities to get up close This sequential layering of deposited material and look back into ‘deep time’ created strata in a vertical timeline with and see what this landscape is younger rocks at the top and older rocks the really made of. Limekilns Limekilns are associated with many of the pits and quarries. These were once used for burning limestone or chalk to produce lime for use as a soil improver Signs on the Surface or to make plaster, mortar The variety of different rock types with varying and concrete. Bishop’s texture, colour, hardness and porosity, can be seen Limekiln [MAP 2] has in the stone used for buildings and the walls of recently been restored. fields. Small quarries and pits were once common across this area, providing local building stone which has given villages their unique and distinctive character. This is very noticeable in Abbotsbury and Portesham, where the grey Purbeck Limestone of Portesham contrasts with the glowing rusty Sinkholes oranges of the Corallian stone used for most Look out for sinkholes, sometimes referred to as buildings in Abbotsbury only a mile away. swallow holes, shakeholes or dolines. These There is a gravel pit circular depressions in the ground are formed near the Hardy where acid gravels overlie the alkaline chalk. Water Monument at Black percolating through the gravel gradually dissolves the underlying chalk, creating a hollow into which Down [MAP 4] where the surface ground collapses [MAP 4]. tumbling golden nuggets cascade into a Springs hollow, surrounded by The many springs in the paths meandering area are an indication of through the heathers where permeable rocks and gorse. You can see above meet impervious clay here the peaty acid below. Rainwater, unable to soil that is formed in percolate any further, these areas and the escapes to the surface. plants it sustains. [MAP 1 + 2 + 3+4+5+6] Rocks of the Ridgeway Gravel The most recent layer of deposition are the gravels, laid down about 42 million years ago by rivers that flowed from the west across what was at the time the flat but eastward tilting Although glaciers didn’t extend this far south in surface of the chalk. the last ice age, the ground was subject to a Later as the land surface pattern of freeze and thaw which weathered these eroded the gravel was hard blocks of sarsen on the hilltops from where left as a topping on they gradually moved to the valleys below. higher ground. Amongst A spectacular example of a sarsen boulder train these gravels can be can be seen in the Valley of Stones [MAP 3]. found pebbles of quartz known to have come from Dartmoor. Sarsen Sarsen stones can also be seen at the roadside and In a few places, conditions resulted in some of built into the walls and buildings in the Portesham these sands and pebbles cementing together to area [MAP 2]. This readily available source of stone form a hard conglomerate rock known as sarsen. lying on the surface was taken advantage of by the Up close these rocks can look very similar to a builders of the stone circles and chambered tombs modern day concrete mix. of the area which are all sited nearby [MAP 2 + 3]. Chalk pit [MAP 4] Flint Found within the Chalk and lying profusely scattered across the land are nodules of flint. Pick up a piece and think of it as a sponge and imagine the landscape you are now walking as a seascape. These knobbly white lumps with their contrasting translucent, glassy inner core were formed by the crystalisation of silica from the skeletons of sea sponges and other microscopic organisms. They often formed around and within the burrows of crustaceans within the chalk sediment, leading to Chalk their distinctive nodular shape. The higher ground of the Ridgeway is Flint was a very important material prior to the predominately Chalk. This soft white stone formed discovery and use of metal. It is very hard and its 90 - 100 million years ago from the microscopic broken edge very sharp, and was used extensively skeletons of plankton and other tiny sea creatures for fashioning tools such as axes, knives and during a period when the sea level was much arrowheads. Examples of flint tools are on display higher and this area was a vast tropical sea. at Dorset County Museum. Purbeck and Portland Limestone Look further back in time at Rocket Quarry near Portesham [MAP 2] where the layers of Purbeck and Portland Limestone have been left exposed. Purbeck Limestone was formed 140 - 145 million years ago in an environment of successive fluctuating forests, swamps and lagoons, each depositing different layers of mud or shell, gradually Upper Greensand compacting to form a hard, pale grey limestone. At the lowest level of this quarry you can see The layer below the chalk is Upper Greensand - a Portland Limestone which formed 145 - 148 sandstone formed 100 - 113 million years ago million years ago in shallow warm sub-tropical seas when sea levels began to rise, flooding much of the close to land and contains fossils from trees and land. plants as well as sea creatures such as ammonites. Tilting of the rocks has exposed this layer in Dry stone walling, places. It can be seen as craggy outcrops on the rather than hedges, slopes above Abbotsbury and at Eggardon Hill is common in areas where it forms a narrow strip of level land or where the Purbeck ‘bench’ between steeper slopes above and below.

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