Quaternary studies in Corsica (France)

QUATERNARY

RESEARCH

9, 41-53 (1978)

Quaternary

E.N.S. Fonrenay Laboratoire

Studies

in Corsica

(France)

de Gkologie du Quaternaire, Centre National de la Recherche ScientiJque, 92190 Meudon, France Received December 23, 1976

Fluvial, glacial, and colluvial deposits in Corsica have been studied in terms of their C~_ distribution, soils, sedimentology (arrangement, shape analysis, size analysis, petrography, and lathering of pebbles; size distribution, shape analysis, and mineralogy of matrix), andrelationships to marine sediments. A relative chronology is based on the topographic and stratigraphic relationships between the sediments, and to a large extent on their degree of weathering. The intensity and the type of pebble weathering suggest a possible correlation of the older alluvial units with the Alpine Quatemary succession. Quatemary paleoclimates in Corsica alternated between glacial and interglacial. During glacial stages, when glaciers developed in the high mountains and formed tongues in the valleys, periglacial climates characterized the low altitude zone. Tectonic movements occurred in Corsica during the Quatemary, probably until the Middle W&m.

clay (26-40% of the particles are <2 pm), and contain very weathered pebbles, those of ophiolites and schists being completely rotted. Alluvium Nr is exposed along the old course of the Bravona River (Fig. 2), in the basin of the Vecchio River, and in the area of Casinca (Fig. 5). Alluvium N,. Paleosols at surface are reddish-orange, as much as 12 m thick, and contain 24-48% clay. The pebbles are very weathered, but not all are rotted. Those of ophiolite have weathering rinds 3-4 cm thick. Along the Go10 River, rhyolite pebbles are often grussified, and most granite pebbles crumble easily. Remnants of alluvium N, are more abundant than those of alluvium N,, although both have been dissected. Deposits of alluvium Nz are found at Pianiccia in the Bravona area, along the old course of the Bravona River to the southeast (Figs. 2 and 5), on the right bank of the Tavignano River in the Aleria plain (Fig. 5), on the left bank of the Corsigliese River, in the Vecchio valley, in the Go10 valley, and on the Piedmont of schistes lust&. Alluvium N,. Paleosols at surface are reddish-orange and as much as 20 m thick. On

INTRODUCTION

This study summarizes the results of several kinds of regional geologic research on Corsica (Fig. 1) (Conchon, 1975). Physiographic and stratigraphic study of &vial and glacial deposits in Eastern Carsestablished the succession of formations. An attempt is made to relate this sequence with those of the Mediterranean and Alpine regions. A detailed analysis of exposures leads to the recognition of tectonkm-ovements, which are consistent with the general evolution of the Tyrrhenian Sea. FLUVIAL DEPOSITS

The succession of fluvial deposits of Corsica is generally in the form of six terraces, each distinguishable by its degree of weathering. Segments of two alluvial sheets older than those found by previous studies (Ottman, 1958; Grelou-Orsini, 1966) were discovered on the eastern Piedmont area (Fig. 2). of the “schistes lust&” This alluvial succession, from the oldest to the most recent deposits, is as follows: Alluvium NI. Paleosols at surface are reddish-orange, about 20 m thick, rich in 41

0033-5894/78%091-0041$02.W/O Copyright AU rights

8 15’78 by the University of Wasbinglon. of reproduction in my form reserved.

P

+

PROVENCAL

(BALEARIC

AlGERO-

BASIN)

BASIN

FIG.

I. Western Mediterranean

+

SEA

Sea showing the location of Corsica

1YRRHENlAN

+

QUATERNARY

m,,+ I

Yioc*m

.:::::.., mIy5 OUI’Sckistes

DN,

&gN3 lurtrbs”

OF CORSICA

@gN2 =N,

Iquidistancr

Ias cwrbw

: IOn.

FIG. 2. Geologic map of Quaternary deposits in the Pianiccia region (Bravona River).

44

ODETTE

the average, they contain slightly less clay (16-42% clay) than the older paleosols. Ophiolite pebbles have a weathered rind 1 cm thick, some schist pebbles are rotted, a few rhyolitic pebbles are powdery, and none of the granites are unweathered. Alluvium N3 is preserved in discontinuous remnants along the valleys. Alluvium Nq. Paleosols at surface are reddish-yellow, 5-20 m thick, and contain 14-37% clay. Some granite pebbles are grussified, but pebbles of rhyolite and schist are not powdery; some ophiolites have a thin weathered rind (l-2 mm). Alluvium N, is the youngest alluvium with reddish soils; it is more extensively preserved than older alluvial units. Alluvium N,. Brown soil (sol brun) at surface is 3-7 m thick, silty, and contains 15-33% clay. Some pebbles of granite and gabbro are powdery; other types of pebbles are hardly weathered. Alluvium N, forms the next-to-lowest terrace along rivers and is nearly continuously preserved. Alluvium N,. Soils are poorly developed are the pebbles are unweathered. The matrix is a coarse, well-sorted gray sand (more than 90% of particles are 50-1600 pm). Alluvium N, forms the lowest terrace in the valleys. Alluvium N,. Gray, well-sorted sand (more than 90% of particles are 50-1600 pm) in the beds of the main rivers. On the coastal plains, it is composed of gray, fine silt that covers alluvium Ng. All of these alluvial units contain many pebbles and cobbles and some boulders (40, 60, 100 cm long); they also contain lenses of sand, but the pebbles are rarely stratified. The sedimentology (roundness ratio and inclination of pebbles in vertical sections) of these formations (including alluvium N, which is disposed in inversion of relief) indicates that the rivers were characterized by a continuous and channelized flow and an irregular discharge. The character of the weathering of the matrix and pebbles has served as a criteria

CONCHON

for mapping and correlation of all the Quaternary deposits of the Golo and Tavignano valleys with the N, to N6--7 regional sequence first established in the Bravona valley (Conchon, 1972). The Piedmont in the area of Marana and Casinca, south of Bastia (Fig. 5), is constructed of the alluvial cones of numerous mountain streams that spread out toward the east. The scarps separating the different alluvial deposits are often gently sloping, but in places are absent. However, stratigraphic distinctions became apparent by comparing the characteristics of alluvial deposits on the Piedmont to those in the Bravona area. The red soils developed in part during the period of nondeposition following each period of deposition, as shown by the reddening in cores taken from the eastern plain, where the alluvia with thick red paleosols are superposed. On the fluvial terraces, the weathering of old alluvium continued during subsequent time; the older the terrace, the stronger the weathering. Corsica is one of the regions where pebbles with weathering rinds are found. An analysis of the weathering of pebbles with rinds (diabase pebbles especially) in alluvia N1, Nz, and N, permits us, by comparing the nonweathered heart of the pebble to the weathered rind (Bieda et al., in press), to characterize the weathering as being of the type “iron-monosiallitisation” as defined by Pedro (1968). Iron oxides result from the hydrolysis of iron-magnesium minerals, and kaolinite is formed when albite is weathered. The type of weathering is the same in alluvia N1, Nz, and N3, but the intensity of these phenomena decreases. In alluvium N1, the majority of the pebbles is completely decomposed; in alluvium Nz, a large number of the pebbles have weathering rinds; in alluvium Ns, only a few pebbles have weathering rinds, and they are thinner than in alluvium N,. Pedological weathering decreases from the older to the younger deposits, and

QUATERNARY

progresses through a continuous evolution of the fersiallitic type for alluvia N1, N,, NS, and N,. The clay minerals in the matrix do not indicate the intensity of the weathering process as well as those of the pebbles. The deep parts of the alluvial units do not constitute the parent material for the soils, because they contain weathered pebbles and minerals resulting from weathering processes; however, the core of pebbles having rinds is the parent material for these rinds. GLACIAL AND GLACIOFLUVIAL DEPOSITS

In the central mountainous region of Corsica, glacial and glaciofluvial deposits have been recognized. Although separated by erosion, three types of sediments are observed successively downstream: glacial deposits, followed by glaciofluvial, then alluvial sediments. The study of these deposits and their weathering enables reconstruction of the depositional succession and establishment of correlations with the alluvial sequence at lower altitudes. In this way, two glacial deposits have been identified and related, respectively, to alluvium N, and alluvium N6. No glacial deposits that can be related positively to alluvium N, or older alluvial units are known, but accumulations of boulders, shoulders on the valley sides, and mammilated rock surfaces downvalley from the N, moraines may represent traces of at least one older glacial stage (Fig. 3). Alluvial deposits, containing randomly scattered coarse pebbles, were deposited principally during glacial maxima and during recessional stages. Finely stratified glaciofluvial sediments, having beds without pebbles or with only small pebbles, were deposited during progressive stages. Near the coastline, in the area surrounding Urbino Pond (Fig. 5), fluvial sediments, correlated with alluvium N5, conformably overlie interstadial marine-lagoonal alIuvium, which indicates that fluvial deposi-

OF CORSICA

45

tion began during the marine regressive period. A difference in the age of deposits within an alluvium along the rivers is indicated by the fact that fluvial aggradation takes place first in the lower reaches of a valley and subsequently in the higher parts during the passing of each glacial period. The deposits of any particular glaciation, therefore, would not be exactly synchronous for the entire length of the river, but relatively older in the downstream area than in the upstream area. SCREES ASSOCIATED WITH GLACIAL AND FLUVIAL SEDIMENTS

The alluvial deposits of Corsica are often overlain by scree or talus which also mantles the valley sides. At middle and low altitudes, one can distinguish scree with red soil and scree with brown soil. A scree stratigraphy can be worked out by studying the superposition of brown scree on red scree (these relations are locally observed in sections along the Go10 River) or on brown alluvium, and the superposition of red scree on red alluvium. The weathering intensity of lithic elements in the screes can also be compared with the weathering of pebbles in the alluvia. The brown screes were formed at the end of alluvial stage N, and were weathered at the same time as N, alluvial deposits. Most of the red screes came to their present location at the end of alluvial stage N4, but they often originate from old weathered products reddened during the same times in which the old fluvial sediments were reddened. In some cases, screes were formed at the beginning of alluvial stage N,, before the deposition of alluvium NS, which overlies these screes without gullying and without an intervening soil. In the mountains, no screes with red paleosols are known. Screes with brown soils sometimes overlie glacial or glaciofluvial deposits of alluvial stage N5, and gray scree covers the sediments of the

46

ODETTE

CONCHON

m GOLO

2600

BASIN

znr 3 .^

N7

? 000

‘:, 1.60

‘...

‘_ : . .. . . . ..

,:’

N3

5H Ii 00

3#0

2H

104

70 0

IO

40

30

n

WURM

RISS Estimated

T 10 yi

time

m

RESTONICA

2500

2500

2400

2000

1500

1500

lb00

1000

% 2.<

:

: .. ;,

:,.: N4

5@0 444

204 RlSS

100

i : : :

10 60 50

R-W Estimated

40

WURM

30

n

500 h x 1000 lO,l n.!!

time

FIG. 3. Schematic representation of glacial limits distinguished in Corsica since the N, glaciation (Riss?) in the upper basin of the Go10 River, and in the valley of the Restonica River (see Fig. 4 for location). Solid lines, based on firm data; dotted lines, inferred.

QUATERNARY

N, alluvial stage in some places. These young screes were not found at low altitudes.

ing alluvial sequence from N4 to N, is available. The only glacial stage which has left unmistakable moraines in Corsica is the Wiirm. Older glaciations of uncertain age are recognized by the shape of valley sides, contrary to the opinion of Rondeau (1961), who postulated only Wiirmian glacial episodes. Three stages of the Wtirm have been distinguished. Red soils of the “ferretto” type were formed during the interglacials prior to the Riss- W&-m period. The later red soils formed during the Lower Wtirm-Middle W&m interstadial show less intensive weathering than the red ferretto soils. In the proposed correlation, there is no record of the earliest Quaternary. Deposits of the Gtinz period (alluvium N,) are not widely preserved, for they were extensively

CORRELATIONS

Chronological correlations between the Quaternary deposits in Corsica and the glacial deposits of the Alps and the F’yrenees are based on degree of weatherings, which provides the only available evidence, because of the lack of fossils of stratigraphic significance and the absence of prehistoric artifacts older than the Mesolithic period. The correlations proposed in Table 1 are based on careful consideration of weathering criteria and on radioisotope chronology when available. The correlation presented here may be revised when more convincing and more decisive information concernTABLE PROMSED

CORRELATION

OF THE

GLACIAL

STAGES

1

QUATERNARY AND

47

OF CORSICA

SUBSTAGES

DEFQSITS IN THE

IN CORSICA

WITH

ALPS

Corsica

Alps

Alluvium N,

Fluvial deposits with poorly developed soil” Cirque glacial deposits

Holocene Late Glacial

Alluvium N,

Gray scree (in mountains only) Fluvial deposits with poorly developed soil Glacial deposits with brown cryptopodzolic soil

Upper Wiirm

Alluvium N,

Brown scree Fhrvial deposits Glacial deposits

Middle Wiirm

Alluvium N,

with brown soil t

Red scree Fluvial deposits with red-yellow Traces of glacial erosion

Lower Wiirm soil

Alluvium N,

Fluvial deposits with red-orange soil Glaciofluvial deposits indicated by the shape of pebbles in the fluvial sediments Scree

Riss

Alluvium N,

Fluvial deposits with red-orange Glacial landscape?

soil

Mindel

Alluvium N,

Fluvial deposits with red-orange Glacial landscape?

soil

Giinz

c(The base of the N, alluvium has been dated in the mountains as approximately deposits; Reille (19731.

10,000 yr BP [r*C in peat

48

ODETTE

destroyed by later erosion. Donau alluvium has likely been entirely carried away by erosion, but this alluvium could perhaps be found by new borings in the area of Marana (Fig. 5). QUATERNARY

PALEOCLIMATES

During the Quaternary period, Corsican climates oscillated markedly from the present climate. The presence of glaciers during the deposition of alluvium N, and alluvium N, is evidence of cold climates in the mountains (Fig. 4). During deposition of alluvium N, (Middle Wtirm?), glaciers formed tongues about 7 km long which extended downvalley to altitudes between 900 and 1000 m. Glacier tongues formed during deposition of alluvium N, (Upper Wiirm?) were 3.5 to 5 km long and terminated at altitudes between 1100 and 1200 m. Toward the end of deposition of alluvium N,, glaciers retreated; ice remained in the cirques near 1750 to 2100 m in altitude during deposition of part of alluvium N, (Late Glacial) before melting completely. During the last Quaternary glaciation, the permanent snowline was at about 1700 to 1800 m in altitude in Corsica; it was at nearly the same altitude in the Southern Alps (Julian, 1966, 1969) and in the Abruzzes Mountains (Demangeot, 1965). This was a lower altitude than that in the Eastern Pyrenees, where precipitation is low (Taillefer, 1969). The Corsican glaciers were also longer than those in the mountains of Morocco (Beaudet, 1969). Palynological interpretation of peat formed in the high mountains after the Late Glacial retreat has enabled Reille (1975) to reconstruct the alterations of warming (Allerod and Atlantic) and cooling (Younger Dryas and Subatlantic) which have marked the Late Wiirm and Holocene in Corsica, as elsewhere in Western Europe. At middle and low altitudes, frost action has affected the rocks along valley sides, and the frost products have been transported by

CONCHON

rain wash and solifluction to the bottom of slopes or onto the fluvial terraces where, at times, they were subject to cryoturbation. Frost action experiments* made on schists taken near screes have confirmed the role of frost in breaking of the rocks. The experiments have shown that frost at -5°C was sufficient to produce many fragments from the schists, often after a relatively small number of freeze-thaw alternations, in each of which complete freezing and complete thawing took place. Frost action does not, however, produce the abundant fine particles present in the natural scree matrix. Weathering of the sediments after deposition seems to be responsible for the sihclay component of the screes. The periglacial area extended down to the present coastline during the glacial maximum correlated with alluvium N, (Middle W&m?). During cold periods, corresponding to marine regressions, the emerged shores were locally subject to deflation and dunes were formed, chiefly on the western coast. The observed periglacial effects are lower in Corsica than in Northern Africa. Their lower limit is 400 m in Eastern Tunisia and is higher than 1000 m in Morocco (Raynal, 1973). However, in Southern France (C.N.A.B.R.L., 1967), they are as low as in Corsica. During periods of interglacial warming, the vegetation must have revived in the formerly periglacial and glacial areas, thus protecting the valley sides from mechanical erosion. In their upper courses, the rivers received fewer frost fragments, had reduced loads, and eroded their banks or former alluvial fills. Downstream, they redeposited some of this eroded material. The climatic conditions and vegetation favored soil development, which resulted in mechanical reduction of particles and chemical weathering of pebbles and minerals in the matrix, and development of clay minerals. ’ We express our thanks to J. P. Lautridou and the Centre de GComorphologie, C.N.R.S., Caen, France.

QUATERNARY

OF CORSICA

::. ,., 1. 1. .:.: kL. .:..“. ‘O SK4 :.: I... -F,.: &f/l ‘.

Vizmmna

ly

FIG. 4. Map of probable extent of permanent snow and glaciers during NB time (Upper Wiirm?). The known positions ofthe N, glacial limits (Middle W&m?) in the drainage of the Asco, Golo, Tavignano, and Vecchio Rivers are also shown.

50

ODETTE

Comprehensive sedimentological analyses of the deposits and their alterations indicate an alternation of glacial and interglacial periods during the Pleistocene, rather than an alternation of pluvial and arid periods as in Africa. If the proposed chronology is correct, it should be possible to observe a difference between the intensity of the weathering of pebbles in Corsica and in the Northwestern Pyrenean Piedmont where such phenomena have been well studied (Icole, 1973). The alluvial deposits ascribed to the Mindel, both in Corsica and in the Pyrenees, have in common a large proportion of pebbles with weathering rinds. Pebbles in alluvium of Riss age in the Pyrenees have no rinds but weathering rinds on ophiolites appear in alluvium attributed to the Riss in Corsica. Perhaps this is evidence of a climatic difference between the two regions during the Riss- Wiirm interglacial. During the Quaternary, Corsica experienced an alternation of periods of strong morphodynamic activity and periods of morphodynamic stability similar to those pointed out by Rohdenburg and Sabelberg (1973) in the Balearic Islands and Morocco. In Corsica, almost nothing is known about the vegetation before the Late glacial. Therefore, it is not known whether these periods were warmer than at present. The study of weathering does not offer an answer, because there is no evidence to prove whether the length of time for weathering was sufficient or not to explain the red paleosols of the early and middle Quaternary. In the plain south of Bastia, however, there is superposition of alluvial units, each of which has a red paleosol; the deepest paleosol was developed between the deposition of alluvium N, and N2 (GiinzMindel?), the second between N, and N, (Mindel-Riss?), and the third between N, and N, (Riss-W&m?). These paleosols are very thick, and the fact that they are overlain by younger alluvial units suggests, in general, the time taken for them to form.

CONCHON

Detailed studies of these buried paleosols would be valuable for improving our knowledge of the effects of Quaternary interglacial climates. QUATERNARY

TECTONICS

This reconstruction of the Quaternary in Corsica would be incomplete without some description of neotectonic movements on the island (Fig. 5). Some small faults cross the marinelagoonal beds of Urbino (Ottmann, 1958; Pilot, 1973). Elsewhere, movements are believed to have caused warping rather than fractures; at least, warping is inferred, for faults are unusual in the loose sediments. Uplift of the eastern zone of “schistes lustres,” along an approximately N-S axis, is evidenced by the upwarping of fluvial terraces of the Go10 and Tavignano Rivers and by the presence of gorges along all the rivers which cross this area (Fig. 5). The uplift of the eastern zone of schistes lustres may have some relation to movement of a “continental flexure” which caused sinking of the old alluvium of the Marana plain relative to the schist zone. Such alluvial units are found 60 m below sea level and may extend to depths of 100 to 150 m below sea level. In the eastern plain, an uplift with an approximately E-W axis has produced a change from south to north in the courses of the Bravona, Golo, and Bevinco Rivers. South of the uplift axis, the course of the Fium Orbo River has moved from north to south during the Quaternary. All the deformations are younger than alluvium N, (Middle W&m?). The deformations are not perceptible in the very recent alluvium Ng, because its depth below sea level, as determined by borings in the eastern plain, is the same as that in other Mediterranean countries, and appears to be related to eustatic changes in sea level. The plain south of Bastia (Marana) and the Aleria plain are different in their tectonic behavior, which influences deposi-

QUATERNARY

51

OF CORSICA

kt+ GOlO t++ ++ -i’+ .

G. 5. Schematic

map of Quaternary

tectonic

phenomena

in Eastern

Corsica.

52

ODETTE

tional and erosional phenomena. The plain south of Bastia has sunk with respect to the schistes lustres and served as a basin in which the Pleistocene alluvia accumulated. The alluvial units which are terraced along the Go10 River are superposed on the plain, according to the scheme of “criss-crossing” presented by Ottmann (1958). But the picture of the Aleria plain is different: This plain, though downwarped in relation to the schistes lust&, is uplifted in relation to continental shelf; therefore, the Quaternary sediments on the Aleria plain are terraced, the oldest being found in high places near the present shoreline. The movement, in particular the upwarping along the different axes that seem to be connected with faults or flexures, cannot be attributed to hydroisostatic adjustment alone. They are also due to tectonic deformation related to the evolution of the Tyrrhenian Sea, where sea-floor spreading may have extended to the Corsica Channel (= Tuscany Trough). MAN IN CORSICA DURING THE QUATERNARY ERA

The earliest traces of human activity in Corsica are apparently Mesolithic [about 8500 years BP, according to de Lanfranchi and Weiss (1973)]. The Neolithic is well represented by ceramics, lithic artifacts, megahths, and human remains. The probability of finding traces of a Paleolithic human settlement on the island is slight. The only shallow place that could serve as a crossing between the mainland and the island is the Corsica channel (between Corsica and Tuscany archipelago). But, at present, it is too deep (-430 m) to have been emerged during the glacioeustatic regressions (Conchon, 1976). Evidently, at some stage in the late Quatemary, man learned how to navigate and crossed from the mainland to Corsica. Grosjean (1971) has presented an expressive picture of the recent evolution of this early man, his life, his rites, and the conflicts between

CONCHON

the “Megalithiques” peoples.

and

“Torreens”

ACKNOWLEDGMENTS This work was performed under the auspices of the Laboratoire de G6ologie du Quatemaire and was supported by the Centre National de la Recherche Scientifique (France). The author is indebted to Drs. H. Alimen and H. Faure for their useful discussions, and wishes to express her thanks to B. Negley, Dr. D. J. Easterbrook, and Dr. G. M. Richmond for the translation of the French text.

REFERENCES Beaudet, G. (1969). “Le Plateau Central Marocain et ses Bordures. Etude G6omorphologique.” Impr. FranGaises et marocaines, Rabat. Bieda, S., Conchon, O., and Icole, M. (in press). Attempted correlation of Quatemary deposits in two regions, Corsica and the Pyrenees, using pebble weathering. IGCP “Quaternary glaciations in the Northern Hemisphere,” Rep. 4. Compagnie Nationale d’Amenagement du Bas-RhoneLanguedoc (1%7). Chronologie des paleosols du Bas-Languedoc. Excursion pedologique. Service Etude des Sols, Nimes. Conchon, 0. (1972). Caractbres g6neraux et chronologie relative des alluvions fluviatiles rub6fites de quelques valltes de Gorse orientale. Bulletin de I Association Francaise pour I’Etude du Quaternaire, 3, 171-184. Conchon, 0. (1975). “Les Formations Quatemaires de Type Continental en Corse Orientale.” These University of Paris. Conchon, 0. (1976). The human settlement of Corsica: Palaeogeographic and tetonic considerations. Journal of Human Evolution 5, 241-248. Demangeot, J. (1%5). “Geomorphologie des Abruzzes Adriatiques.” C.N.R.S., France. Grelou-Orsini, C. (1966). Problbmes de chronologie du Quatemaire continental en Corse. Congres Prehistoire France, Ajaccio, pp. 90-94. Grosjean, R. (1971). La prehistoire. La protohistoire. In “Histoire de la Corse,” privat ed., pp. 12-33, 35-65. Coil. Univers de la France, Toulouse. Icole, M. (1973). “Geochimie des Alterations dans les Nappes d’Alluvions du Pitmont Occidental NordPyrenBen. Essai de PaMop6dologie Quatemaire.” These. Paris. Julian, M. (1966). Les montagnes du Haut-Var. Esquisse morphologique. Mgditerranie 7, 186-209. Julian, M. (1969). Le glaciaire quatemaire des AlpesMaritimes (versant fran~ais). Rev. M6direrranCe Suppl. I, 49-53. Lanfranchi, F. de, and Weiss, M. C. (1973). La stpulture pr6ndolithique de la couche XVIII de

QUATERNARY l’abri d’Araguina-Sennola (Bonifacio, Corse). Bulletin de la Sock%! des Sciences Historiques et Natwelles de Corse 606, 7-17. Ottmann, F. (1958). “Les Formations Pliocbnes et Quatemaires sur le Littoral corse.” Mtm. Sot. Geol. France, No. 84. Pedro, G. (1968). Distribution des principaux types d’alteration chimique a la surface du globe. Presentation dune esquisse geographique. Revue de GCographie Physique et Gkologie Dynamique X(2), 457-470. Pilot, M. D. (1973). La tectonique recente dans la region d’urbino-Vadina (Corse orientale). Comptes Rendus de la Societe G6ologique de France, 4, 121-123. Raynal, R. (1973). Quelques vues d’ensemble B propos

OF CORSICA

53

du p&iglaciaire pltistocene des regions rivet-antes de la MCditerranCe occidentale. Biuletyn Perygl, Lodz, 22, 249-2.56. Reille, M. (1975). “Contribution Pollenanalytique a I’Histoire Tardiglaciaire et Holocene de la Vegttation de la Montagne Gorse.” These. University of Marseille. Rohdenburg, H., and Sabelberg, U. (1973). Quart&e Klimazyklen im Westlichen Mediterrangebiet und ihre auswirkungen auf die Relief-und Bodenentwichlung. Catena 1, 71-180. Rondeau, A. (l%l). “Recherches Geomorphologiques en Gorse.” Armand Cohn, Paris. Taillefer, F. (1%9). Les glaciations des Pyrenees. In “Etudes Francaises sur le Quatemaire.” VIII Congress INQUA, pp. 19-32.