In January and February of 2010, beach deposits at Redcar – in an area roughly extending between the Information Center and Park Hotel – were stripped away by tidal scour revealing some infrequently exposed beds beneath the usual sand and pebbles.

At the base of the steps opposite the Information Center, and extending seaward for over 100 metres, were exposed black peat beds, springy underfoot, packed with wood fragments and even tree trunks, some in growth position. This is the Redcar Submerged Forest (aka. Peat & Forest Beds). Other minor examples survive within the Lower Tees Valley, both underlying parts of Middlesbrough and also beneath beach deposits between Seaton Carew and Hartlepool. Here the beds are known as the Hartlepool Submerged Forest.

The peat and tree trunks date from a time shortly after the last great ice-sheets (glaciers) to occupy this part of N.W. Europe retreated northward as the climate warmed c.13,000 years before present (BP). When immense ice-sheets form, like those which occupied N. Britain during the last Ice-Age, prodigious amounts of water are sequestered as ice, a process which draws down global sea-level. When the climate recovers, the ice-sheets melt and sea-level gradually rises again.

By c.10,000 years BP, ice which once occupied Northern England had retreated, and the newly exposed post-glacial landscape was recolonised by vegetation. Sea-level was still some 150 metres, or so, lower than today and the place where Redcar now stands was part of a forested upland similar in altitude to nearby Upleatham Hill!

Continued wastage of the ice-sheets farther north gradually raised sea-level until between 8,000 and 6,000 years BP, it attained its modern position in the process overwhelming the ancient forest and producing the Peat and Forest Beds. The deposit was formerly much more extensive though most of the remains have been removed by modern erosion.

These are important deposits which can tell us a great deal about the changes in global temperature, sea-level fluctuation, and vegetative cover that have occurred in the Tees Valley over that last 8,000 years or so. As such they should not be disturbed – please visit them (when exposed) but leave them for the enjoyment and edification of others.

Since this article was written construction of a new sea-wall at Redcar has commenced. These important deposits have been given NO protection and will be partially lost when works are complete.

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1. Introduction
2. Devensian
3. Holocene

Introduction

Sub-divisions in the Quaternary of the British Isles.

The Quaternary Period is the shortest division of time in the geological column covering only the last 2.6 million years or so of Earth’s history. The period is characterised by extraordinary changes in global climate producing several major phases of ice-sheet advance, (glacial), and retreat (interglacial) across lower latitudes than permanent ice cover is restricted to today. Many minor cycles of advance and retreat are superimposed upon each major phase making deposits of this age difficult to interpret and correlate between different areas.
 
Furthermore, each re-advance more-or-less erases the evidence of any preceding glacial activity exacerbating the problems facing Quaternary geologists. Because of this analysis of pollen grains (palynology) and oxygen isotopes provide some of the best clues to the different environments under which deposits of this age accumulated.
 
The Quaternary can be sub-divided into two series, the Pleistocene – which covers all deposits between 2.6 million years and around 20,000 years ago (locally), and the Holocene – encompassing deposits from around 20,000 years ago to the present day.
 
Solid rocks of the Tees Valley district below c.300m are covered by till, sand and gravel laid down by wastage of the local ice-sheet at the close of the most recent glacial episode. The youngest deposits in the district are the Flandrian sand dunes and estuarine silts, sands and clays currently being deposited around the the mouth of the River Tees.

Devensian

The most recent ice-sheet to occupy the Tees Valley did so during the Devensian Stage of the Pleistocene, between around 120,000 and 20,000 years before present, when ice advanced on the area from seats in the Lake District to the west, and Scotland to the north. Pressure, applied by Scandinavian ice from the North Sea Basin, affected the advance locally by forcing the Scottish ice stream inland at suitable low points in the landscape.

View of Freeborough Hill looking south east from Stanghow Ridge.

Some landforms, such as Freeborough Hill, were sculpted as the ice-sheet carved up the original landscape during advance. Others, such as Cat Nab at Saltburn, resulted as the ice melted and the material which had been acquired en-route was unceremoniously dumped. Immense amounts of melt water, unable to escape in any other direction, flowed along the ice margins forming temporary lakes where conditions allowed. Longer-lived water bodies tended to fill until they eventually overflowed, the escaping streams often cut distinctive channels which were abandoned as flow rates diminished. Water also travelled through, beneath and upon the ice-sheet where conditions allowed.

The most extensive evidence of former occupation by ice-sheets is a thick deposit of boulder clay (or till) which cloaks the landscape, softening its contours to heights of between 250 and 300 metres above sea level. This material has also in-filled some of the pre-Devensian features producing buried valleys, most notably at Upgang and Saltwick Bay, near Whitby.

Boulder clay is a mixture of clay-, silt- and sand-sized particles (dubbed rock flour) within which grit, pebbles and boulders are embedded. It forms as an ice-sheet advances and tears up the bedrock over which it passes. Large boulders enhance ice’s abrasive ability and are gradually pulverised by movement of the ice to form rock flour. When ice-sheets eventually melt the boulder clay left behind contains fragments of rock acquired en-route which are non-native to the district in which the clay ends up being deposited. These erratics provide important clues to the source and route taken by the originating ice.

Holocene

Since the retreat of the Devensian ice-sheets, around 20,000 years ago in the Tees Valley and Cleveland, many changes have occurred to the landscape. On both sides of the River Tees, at Seaton Carew and Redcar, are ancient peat deposits buried beneath the sands on the beaches. These date from around 8,000 years ago.

As water becomes locked up in the form of ice, so sea levels fall. Even though ice had left the area by 8,000 years ago, sea levels were still much lower than they are today. Up to 150m lower. Forest extended far seaward from Teesside at this time, it was later occupied by early human resettlers. Finds at Seaton Carew include signs of flint-working, a skull, wattle-work and much more, and the Peat & Forest Beds have been designated a SSSI. No such work has been undertaken at Redcar despite the ongoing sea-defence work and these valuable deposits are likely to be lost.

Tree-trunk in the Redcar Peat & Forest Beds.

Eventually, c.6,000 years ago, sea levels rose to (roughly) their present levels and the former forest was overwhelmed. The only clues to its former existence these two patches of peat on either side of the River Tees estuary. As these deposits contain evidence of past sea-level change, they are a valuable resource for the study of future sea-level rise.

« Tertiary

©2011 Tees Valley RIGS Group.