The Coastal Slope Deposits of the Northern Cotentin PeninsulaAuthor(s): Edward WatsonSource: Area, Vol. 1, No. 1 (1969), pp. 28-29Published by: The Royal Geographical Society (with the Institute of British Geographers)Stable URL: http://www.jstor.org/stable/20000312 .

Accessed: 17/06/2014 07:19

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

The Royal Geographical Society (with the Institute of British Geographers) is collaborating with JSTOR todigitize, preserve and extend access to Area.

http://www.jstor.org

This content downloaded from 62.122.76.45 on Tue, 17 Jun 2014 07:19:20 AMAll use subject to JSTOR Terms and Conditions

Annual Conference - Academic Sessions

than the present one: they meet the sea in Spencer Gulf in South Australia where Jessup (I968) has fitted them into a sequence of sea-level change. On the other side of the tropical high pressure belt in the R. Fitzroy estuary in West Kimberley, various observers have noted, as I did in I959, that the fixed longitudinal dunes appear to dive under estuarine deposits. Fairbridge (I964) has gone further and argued from inferred estuarine burial to Last Glacial age for these dunes and to Last Glacial aridity for Australia at large. In I967 I carried out field work there during the dry season, some laboratory results are also available, but more field and laboratory work is planned.

This paper is therefore interim in nature. The stratigraphic evidence confirms the superficial appearance of burial of relict

desert dunes by estuarine fill. So far dunes have only been traced down to M S L with the implication that sea level was at -55 m. or lower.

The coastal slope deposits of the northern Cotentin Peninsula Edward Watson, University College of Wales, Aberystwyth

These head deposits form a terrace sloping seaward, with a general correlation between the height of the cliffs cut into them and the height of the rock slope at the rear. The head cliff varies from 2 m. high, below a back slope of 10-13 m., south of Barfleur, to 30-40 m. below slopes I60-I70 m. high at Herquemoulin.

The deposits are generally interpreted as banked against an old cliff line and are frequently seen to rest on raised beach gravels at the junction of the head and the rock cliff. In the central parts of the bays the basal beds consist of grey silty and gravelly flows sometimes enclosing lenses of organic silt, the total being up to 2 m. thick.

These beds appear to rest on rock and have been found in hollows in the present shore platform south of Herquemoulin. Overlying them there may be a couple of metres of thin beds of silt, sand and gravel, some being open work, especially on granite, arkose and quartzites. They appear to be weakly developed on greywakes and shales. On top of these is a coarse angular head with a rough stratification which makes up the greater part of the exposures.

Fabric studies at i6 sites show that the preferred stone orientation is sub-parallel

to the hill slope at the rear of the site. The roundness index, a0o o, for mean lengths

between 40 and 6o mm. varies from 40 to io8. At I3 of the sites the mean round ness of curvature for the sharpest angle is less than 2 mm.

In the discussion which followed Colin Lewis (University College Dublin) asked whether Dr. Watson had: a) noted more than one beach; b) seen Levalloisian flints in the beach he described? Dr. Watson replied that he had neither seen more than one beach nor implements in the beach. Dr. Lewis doubted therefore if it were feasible to date the beach to the Last Interglacial; might it not be older, especially since the depth of head quoted (40 m.+) appeared to equate with the Main Head of Devon, Cornwall, Cork and Kerry? The Main Head is believed to be of Mousterian Age (Stephens I969). Dr. Watson replied that the depth of head was variable as it was in south-west Britain. Comparisons of thickness between the two areas were valid only in comparable topographic situations and on comparable lithologies. Elhai records

worked flints at several points in the Cotentin in the head. Some are Upper Leval loisian types which must belong to Riss-Wiirm or early Wurm.

A. Young (University of East Anglia) stated that studies of this type, which show

28

This content downloaded from 62.122.76.45 on Tue, 17 Jun 2014 07:19:20 AMAll use subject to JSTOR Terms and Conditions

Annual Conference - Symposia

that periglacial deposits are widespread in occurrence and of considerable thickness, have implications for the study of erosional topography. Such material must have come

from somewhere. Where exposed, as in the present instance, in a sea cliff the ob served amount of deposited material is a minimum estimate of its original quantity, since prior to modern cliffing the deposit extended farther seaward. Had any estimate of the total volume of this deposit been made? What proportions of it came from the 'pre-Head' cliff, that is, free face, and from the slope above this cliff? And, in par ticular, how is the volume of the deposit related to the area of slope from which it was derived -as an order-question, is it equivalent to the removal of a layer of thickness IO cm., I m., Io m., or more? If the latter, then the implication is that present slope form is largely the product of periglacial weathering and denudation, little related to present-day processes. Dr. Watson replied that he had not attempted to calculate the total volume of head deposited because of difficulties in estimating its original extent

and form. The proportion from the old cliff was, however, relatively small.

Relict Landscapes

The Agrarian Landscape Research Group met at the Annual Conference on i January

to discuss the study of relict landscapes. Hugh Prince (University College London) opened the discussion with a paper on

Relict features: the past in the present, distinguishing two approaches to the study of relict features: using the present as a key to understanding the past, and the past as a

key to understanding the present. Field observations raise and may resolve questions upon wbich documents are

silent. The extent of early modifications to the land surface may be gauged from

changes that have occurred in recent times, or may be tested experimentally. The

Kon Tiki expedition has proved the feasibility of crossing the Pacific on a balsa raft

and the efficacy of flint axes for clearing woodland has been demonstrated by felling live trees with replicas of neolithic implements.

The reconstruction of the past from the present, by what Maitland called 'the retrogressive method', proceeds from the better known to the less well known. It follows the trail backwards, one careful step at a time, from the visible real world to the obscurity of the Dark Ages.

All features in the present landscape are relict features, survivals from some past

period. Constant reference to past events is necessary to understand how they came

to occupy their present positions, but not all past events are equally important. The depth to which the past is fathomed depends on the level of causation being sought.

Wreford Watson treated relict features not only in the present scene but as objects produced by continuing processes of change, considering them 'indicators of the ever moving frontiers of the past which make up the ecology of the present'.

29

This content downloaded from 62.122.76.45 on Tue, 17 Jun 2014 07:19:20 AMAll use subject to JSTOR Terms and Conditions