Impaginato Amato Robustelli


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1 Dip. to di Scienze della Terra, Università degli Studi di Napoli “FEDERICO II”; amatoa@unina.it

2 Dip. to di Scienze della Terra, Università degli Studi della Calabria; robustelli@unical.it 

ABSTRACT
A 130m thick sedimentary alluvial to slope deposits (Nocella Formation) rests on a concave up spur suspended between 660m and
800m on the southern coastal slope of the Sorrento Peninsula have been analized. Stratified slope waste deposits (Nocella breccias)
unconformably and abruptly rest on Nocella alluvial deposits (Nocella Conglomerates). Facies analysis of the Nocella Conglomerates
indicate a high-energy, gravel bed braided environment. In particular two facies association have been distinguished. The first one is
representative of in-channel deposition and both vertical accretion and lateral and downstream migration of gravel bars. The second
one reflect vertical accretion and downstream migration of low-relief gravel bars and extensive, locally in-channel, deposition by high-
energy flood flows respectively. Paleocurrent data indicate a WNW-sloping paleoslope away from a, nowadays, lacking highland.
Techniques of lateral profile analysis and hierarchical ordering of bounding surfaces has also been applied to the Nocella
Conglomerates, and allows two different river model to be outlined. 
Slope deposits also taper upslope coating a triangular facet belonging to the first fault scarp generation which occurred after the forma-
tion of the I order palaeosurface sailed by Nocella Conglomerates; they are cut by the second fault scarp generation together with relics
of the II order palaeosurface such as the Agerola karst basin and the S.Maria del Castello erosional surface. We correlate the Nocella
alluvial deposits with the S. Maria del Castello relic of II order palaeosurface and thus we propose a reconstruction of a part of the
Sorrento Peninsula Early Pleistocene landscape. The source area of the Nocella Conglomerates should be a mountainous area located
east-southeastward of Nocella site and should be the same as, on the opposite side, fed the clastic infilling of the Agerola karstic basin. 

RIASSUNTO
Sul versante meridionale della Penisola Sorrentina, in corrispondenza di uno sperone sospeso tra 660m e 800m s.l.m., affiora una suc-
cessione sedimentaria spessa circa 130 m costituita da depositi alluvionali su cui poggiano depositi di versante. I depositi di versante
(Brecce di Nocella) giacciono in discordanza sui depositi alluvionali (Conglomerati di Nocella). L’analisi di facies sulla porzione alluvio-
nale della successione è indicativa di un ambiente fluviale ad alta energia di tipo braided. In particolare sono state distinte due associa-
zioni di facies la cui differenza principale risiede nella maggiore o minore presenza di unità canalizzate, oltre alle loro geometrie, e nei
caratteri geometrici delle forme migranti (barre). La direzione misurata delle paleocorrenti, che è WNW, evidenzia un chiara discordan-
za oroidrografica, in quanto l’attuale paesaggio manca completamente dei rilievi alimentatori. Nell’ambito delle porzione alluvionale
della successione affiorante sono state applicate tecniche di analisi laterale dei depositi e di ordine gerarchico delle superfici che limita-
no i principali elementi architettonici individuati al fine di caratterizzare la tipologia di modello fluviale. 
I depositi di versante mantellano versanti a faccette triangolari derivanti dal modellamento della scarpata di faglia di prima generazione
che ha smembrato e dislocato il I ordine di paleosuperfici ed è stata fossilizzata dai Conglomerati di Nocella. Essi sono dislocati da una
ulteriore fase tettonica insieme ai relitti del II ordine di paleosuperfici, correlabili con quelli che bordano la conca carsica di Agerola e
con la paleosuperficie di Santa Maria del Castello. Considerazioni di carattere morfostratigrafico ci hanno consentito di correlare  i
Conglomerati di Nocella con il relitto di II ordine di peleosuperfici di Santa Maria del Castello, e pertanto proponiamo una ricostruzione
del paleopaesaggio che caratterizzava questo settore della Penisola Sorrentina durante il Pleistocene inferiore. Tale paleopaesaggio,
che prevede la presenza di una area montuosa sorgente dei Conglomerati di Nocella a ESE della successione analizzata, probabil-
mente fungeva da area sorgente anche per i depositi che costituiscono il riempimento clastico della conca di Agerola. 

Keywords: palaeosurfaces, fluvial deposits, facies analysis, Sorrento Peninsula, Early Pleistocene.

Parole chiave: paleosuperfici, depositi fluviali, analisi di facies, Penisola Sorrentina, Pleistocene inferiore.

Il Quaternario
Italian Journal of Quaternary Sciences
1155(1), 2002, 83-96

11..  IINNTTRROODDUUCCTTIIOONN

The Sorrento Peninsula is an ENE-WSW trending
morphostructural high interposed between the
perytyrrhenian depressions (grabens) of the Gulf of
Naples-Campana Plain to the North, and the Gulf of
Salerno-Sele Plain to the South (Fig.1). It consists
mainly of a Mesozoic carbonate units (the Picentini
Mts.-Mt. Taburno tectonic unit; Bonardi et al., 1988) and
of a Miocene terrigenous synorogenic units. Due to its
position (it is one of the westernmost outcropping part of
the Southern Apennines Chain) together with the con-
servativity of its lithologic units, the Sorrento Peninsula
represents important evidence of the early phases of

post orogenic morphostructural evolution of the
Southern Apennine Chain (Cinque et al., 1993).

As regards the structural setting of the Sorrento
peninsula, it represents a NW dipping monocline which
is dislocated into minor blocks by two systems of high
angle fault trending NW-SE and NE-SW. In particular
the anti-apenninic system is responsible for formation of
the grabens of Napoli and Salerno (Bartole et al., 1984;
Sacchi et al., 1994); an E-trending system fault has con-
tributed to the development of the first one too. Previous
Authors distinguished up to five block-faulting phases
during Plio-Pleistocene time on the basis of structural
data (Torrente et al., 1999). By a morphostructural point
of view, there are three main deformation phases



84 A. Amato - G. Robustelli

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(Caiazzo et al., 2000), which  occurred during the Early
Pliocene-late Middle Pleistocene time interval, in
response to the eastward migration of the Thyrrenian
extensive domain (Sartori, 1989, 1990). The presence
of raised marine terraces indicates the uplift of the
Sorrento peninsula from the Lower Pleistocene to the
Middle Pleistocene, during which the width of the penin-
sula was progressively reduced by block faulting that
affected the southern flank enlarging the contiguous
Gulf of Salerno (Cinque, 1986). The emerged marine
terraces along the southern slope of the Sorrento penin-
sula allow Cinque & Romano (1990) to infer that the
latest phases of block faulting occurred during the late
Middle Pleistocene and that Sorrento peninsula stopped
rising no later than the last interglacial. On the contrary,
the nearby Campana-Plain graben has continued to
subside during the Upper Pleistocene to present time
(Milia, 1996). 

Since no absolute chronological constraints have
ever been reported, the different stages in which the
morphostructural evolution of the Sorrento Peninsula
have been divided are only relatively dated. The begin-
ning of the geomorphologic history of the Sorrento
Peninsula is as old as the formation of the I order
palaeosurface, suspended up to 1300 m a.s.l. on the top
of Mt. Faito (Fig. 2), which has been ascribed to a pro-
bably Early – Middle Pliocene time (Caiazzo et al.,
2000). The oldest geomorphological elements are few
hanging relics remnants of mature erosion landscape (I
order palaeosurface). After a phase of block faulting that
disrupted and uplifted the I order palaeosurface, a new
base-level established some hundreds of meters below.
In this paper we attempt to reconstruct the landscape of
this geomorphological stage, now broken and suspen-
ded up to 850 m a.s.l., by considering different types of
evidences preserved in the studied area and by analy-
sing the stratigraphic and sedimentological characteri-
stics of the here informally named Nocella formation.

22..  GGEEOOMMOORRPPHHOOLLOOGGYY

The Sorrento Peninsula is characterised by a clear
structurally controlled landscape, as it is dominated by
the occurrence of fault scarps and structural cliffs and
valleys (Figg. 1, 2). Moreover, due to the vicinity of the
sea, the area experienced a great number of eustatic
controlled fluvial dissectional cycles, which actively con-
tributed to reduce or even cancel the erosional
landforms modelled during the pauses of the tectonic
activity. Nonetheless, clear traces of  ancient erosional
cycles occur and we attempt to interpret them in terms
of palaeoenvironment and relative age.  

In the geomorphological map of Fig. 2, the main
structural, erosional, and depositional landforms of the
Eastern Sorrento Peninsula are reported, and the relati-
ve inferred ages are also proposed (see section 4 for
discussion). Two sectors have been distinguished: the
eastern one, which is dominated by the high homoclinal
calcareous block of Mt. Faito, and the western one,
which is sensibly lower. The two sectors are separated
by the fault scarp of Mt. Faito which transversally cros-
ses the Peninsula.

On  both the sectors we recognise relics of
palaeosurfaces testifying the occurrence of past phases

85The Nocella Conglomerates ...

of relief smoothing under the control of both local and
general baselevels of erosion. Most of the relics cut
across dipping strata, but in some cases they rest on
almost horizontal strata. In few cases (e.g., Faito,
Agerola) they are associated to outcrops of undated
continental conglomerate. More frequently, these surfa-
ces lack any type of deposits, so that their chronology is
uncertain. 

The only ancient (Early Pleistocene?) clastic depo-
sits are the Nocella alluvial deposits (see section 3)
suspended between  700 and 775 m a.s.l., on a policy-
clic slope. More precisely, these deposits are cut by the
free face of a coastal fault scarp whose slope is about
35%. Above this free face the slope changes in about
25% and appears concave up to the summit where the
top surface of Mt. Faito occurs. This change in slope
gradient is due to a different lenght of the erosional pro-
cesses which caused the decline and the slope replace-
ment of the relative fault scarp planes.

The more ancient erosional cycle is well represen-
ted by the highest  relics of palaeosurface occurring on
the eastern uplifted block, indicated on the map of Fig. 2
as the I order palaeosurface. 

The relics of the I order palaeosurface are almost
reduced to flat watershed, but locally (see the top of
ridge that limits the Agerola plain to the East) they inclu-
de also wind gaps clearly unlinked to the modern valley
network. As mentioned before, on the top of Mt. Faito
these surfaces are associated with the outcrop of seve-
rely eroded clastic deposits, interpreted as slope and
fan breccias, produced when the base level was very
near to those of the I order palaosurface landscape. The
Mt Faito palaeosurface could be Upper Pliocene in age,
since it is younger than the Miocene N-verging thrust-
sand older of the phase of normal block –faulting (pro-
bably Late Pliocene – Early Pleistocene (Aucelli et al.,
1996). 

The slope fault scarp of the Sorrento Peninsula
can be divided in two main groups: a first characterized
by concave up profiles with mean gradients of about 25
– 30 % , standing on the highest portions of reliefs,
locally just behind the relics of the I order palaeosurface;
the other ones is represented by the lower tracts of slo-
pes, characterized  by higher gradients (in the order of
40 % and more), convex profiles frequently disrupted by
parallel fault planes.

These two different types of slope profile are local-
ly separated by relics of the II order palaeosurface, that
occur on both the eastern and the western sector. It is
probable that part of the II order relics, as well as some
lower erosional terraces must be interpreted as down-
faulted portions of the I order palaeosurface that were
simply remoulded during the pause of the tectonic acti-
vity that allow the II order palaosurface to be formed.
Different examples of this type are widespread on the
western downfaulted sector of the study area. We will
describe two cases: the surface of the Agerola karst
basin, and the S.Maria del Castello surface. 

The Agerola graben was formed by the tectonic
phase that disrupted the I order palaeosurface by the
normal activity of the N-S trending faults on which the
western slope of the Sproviere  - Murillo ridge and the
eastern slope of Mt. Tre Calli ridge are sculptured. The
top surface of the graben can be considered a II order
surface, it is a policyclic surface suspended at about



86 A. Amato - G. Robustelli

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87The Nocella Conglomerates ...

650 m a.s.l.  The graben infilling outcrop of few tens of
meters in river incision and consists of a polygenic
angular conglomerate composed of carbonatic and
subordinate terrigenous clasts, the latter derived from a
Miocene terrigenous unit outcropping during Early
Pleistocene time and then tectonically drowned under
the sea of the Salerno Gulf. Due to the bad exposition, a
more precise facies interpretation and source direction
are not available for these deposits, except for those
outcropping along the rim of the graben, which are at
the top of the clastic infilling body and can be interpreted
as slope breccias deposits. We don’t have enough ele-
ments to establish if the endoreic conditions date back
to the birth of the graben or if they developed after, but
surely they had a long duration as demonstrated by
signs of remarkable karstic planation along the borders
of the basin, suspended at about 630 and 570 m a.s.l..
The epikarstic activity was interrupted by the tectonic
phase that downfaulted the southern rim of the Agerola
intramontane endoreic basin and promoted its capture
by the retrogressive deepening of the Schiato stream
gorge.

The S. Maria del Castello surface is located on the
western sector, it is an erosional landsurface suspended
upon Positano town at about 650 m a.s.l. with the shape
of a low gradient wide valley tract NW dipping. It is  trun-
cated by a fault scarp NE-SW oriented and  dipping to
the North, whose characteristics are those typical of the
second, more recent type of slopes.

Toward the NE the S. Maria del Castello II order
surface confine with the base of the Punta Medico
slope, which is one of the triangular relics of the first
type fault scarps formed by slope replacement and then

deeply dissected.
Near S. Maria del Castello, entrenched within the

II order palaeosurface are other terraced alluvial fan
conglomerates, suspended between 500 and 550 m
a.s.l. (Moiano conglomerates). Similar deposits occur
near Pimonte, on the northeastern side of Mt. Faito.
Both Moiano and Pimonte conglomerates are suspen-
ded and hence older than the other dissected alluvial
fan occurring at lower elevations and located in the
lower tracts of the valleys. These younger alluvial fans
are Middle and Late Pleistocene in age. Similarly, the
traces of marine terraces suspended between 6-8 m
and 50 m a.s.l. on the southern coast are Late
Pleistocene to Middle Pleistocene in age (Cinque &
Romano, 1990). On the basis of the existing knowledge,
the Moiano and Pimonte conglomerates can be referred
to a generic Middle Pleistocene.

33..  NNOOCCEELLLLAA  FFOORRMMAATTIIOONN

The Nocella Formation. lies with pronounced
angular unconformity upon Jurassic dolomitic limesto-
nes, which constitute the bulk of the relief. The best
exposed stratigraphic section , about 130m thick, out-
crops on a hanging, concave up spur ranging between
660m and 800m in elevation (Fig. 3). Here stratified
slope waste deposits (Nocella breccias) rest unconfor-
mably on Nocella alluvial deposits (Nocella
Conglomerates) proofing that their deposition occurred
soon after the alluvial one. Slope deposits tend to taper
upslope coating a triangular facet which is one of the
triangular relics of the Scrajo-Vettica fault scarp on

Fig. 3 - Overview photograph of the studied section. The location of the logs are marked and numbered. The Nocella formation, resting
uncomformably above Jurassic limestones, consists of alluvial deposits (Nocella Conglomerates) overlaid by slope breccias (Nocella
breccias). The northern segment of the Scrajo-Vettica fault is also marked.

Panoramica dell’area studiata. S1 ed S2 indicano le sezioni esaminate. La formazione di Nocella, discordante sui calcari giurassici, è
costituita da una porzione inferiore alluvionale (Conglomerati di Nocella) passanti verso l’alto a brecce di versante (Brecce di Nocella).
In figura è inoltre segnalata la traccia del segmento settentrionale della faglia Scrajo-Vettica. 



88 A. Amato - G. Robustelli

which the south-eastern slope of the Mt. Tre Calli ridge
are sculptured by slope replacement processes coupled
with consequent river dissection. The basal angular
unconformity represent an asymmetric paleovalley into
which Nocella Conglomerates were deposited and, in
particular, sail the north-eastern segment of the Scrajo-
Vettica fault zone. 

Steep and high scarp perimeters the spur at issue
which reflects the re-activation of the the Scrajo –
Vettica fault zone and its dissection by consequent inci-
sions characterised by steep flanked V-shaped valleys
having high longitudinal gradients. Their longitudinal
cross-profile is characterized by upper reach steeper
than the slope they dissect.

The Nocella Conglomerates, about 90m thick, has
been chosen as a type section for detailed description of
the sedimentary facies. As the vertical cliff which confi-
nes the spur does not allow a complete sedimentary log
to be given, only the middle and the upper portion of the
Nocella Conglomerates  have been analysed in detail
(Fig. 3); they outcrop on the north-western and south-
eastern part of the spur respectively. Minor exposures of
clastic deposits belonging to the same morphoevolutive
stage occur close to hanging, concave-up footslope of
the Scrajo-Vettica Fault zone. 

The Nocella type section consists of a crudely CU
sequence characterized by the dominance of conglome-
rate lithofacies (>95%) with very subordinate sandstone
lithofacies. Fine grained lithofacies were not observed.
Conglomerate lithofacies are clast supported, poorly to
moderately sorted, and contain angular to subrounded
clasts. Clast size is generally in the pebble to cobble
range although boulders up to 30 cm occur in the top-
most part of the sequence. The lithology does not vary
over the study area; dominant clasts include white to
greyish dolomitic limestone mainly of Jurassic age
(coming from the Jurassic part of the local Mesozoic
succession). Rare clasts of Miocene flysch deposits also
occur, suggesting that Miocene terrigenous deposits
outcropped in the source area of Nocella
Conglomerates. 

33..11  LLiitthhooffaacciieess  ddeessccrriippttiioonn
The Nocella Conglomerates is characterized by

six sedimentary facies distinguished on the basis of
sedimentary structures and bed geometry. Paleocurrent
data indicate WNW-ward paleoflows close parallel to the
Scrajo-Vettica fault zone. Two sedimentary logs are
given in Fig. 4; they are representative of the middle and
the upper part of the Nocella Conglomerates and are
located respectively along the NW and SE side of the
spur (Figg. 3 and 4). Table 1 summarizes the lithofacies
codes used in describing Nocella Conglomerates, based
on the fluvial lithofacies code modified from Miall (1996).

LLiitthhooffaacciieess  GGccmm  ––  SSttrruuccttuurreelleessss,,  ccllaasstt--ssuuppppoorrtteedd  ccoonn--
gglloommeerraattee

This facies consists of pebble to cobble-size clasts
subangular in shape; they are moderately to poorly sor-
ted and display a clast-supported texture (Fig. 5). Matrix
content is generally less than 20% and consists of coar-
se sand and granules. Conglomerate fabric is disorgani-
zed, although it appears locally to be a preferred clast
orientation. The longest a-axes of some elongate clasts
are parallel to paleoflow directions; locally a(p)a(i) fabric

Fig. 4 - Logs of the Nocella Conglomerates along the north-
western (S1 in Fig. 2) and south-eastern (S2 in Fig. 2) side of
the Nocella spur (Fig. 2). Letters refer to lithofacies and arrows
indicate paleocurrent. The paleocurrent rose refers to the total
number of measurements. 
Sezioni stratigrafico-sedimentologiche dei Conglomerati di
Nocella sul lato nord-occidentale (S1 in Fig. 2) e sud-orientale
(S2 in Fig. 2) dello sperone visibile in Fig. 2. Le sigle si riferi-
scono alle litofacies mentre le frecce indicano la direzione delle
paleocorrenti. Il diagramma si riferisce al totale delle misure
effettuate.

mode occur. Grading is absent or basal inverse grading
and crudely normal grading locally occur. The conglo-
merates consist of lenticular or laterally apparently conti-
nuous, non erosive-based units whose thickness range
between 10 to 45cm. This lithofacies occurs mostly in
the upper part of Nocella Conglomerates and is inter-
bedded with Gci and Gh lithofacies 

LLiitthhooffaacciieess  GGccii  ––  IInnvveerrsseellyy  ggrraaddeedd,,  ccllaasstt--ssuuppppoorrtteedd  ccoonn--
gglloommeerraattee

This facies consists of pebble-size clast, although
cobbles up to 20 cm locally occur. The clasts are angu-
lar to subrounded; they are moderately sorted and cha-
racterised by a clast-supported texture, with a coarse
sand matrix locally absent. Inverse grading is well deve-
loped and a(t)b(i) fabric mode is locally present. Beds of
this facies have sharp non erosional lower contacts and
occur in lenticular units that are up to 30 cm thick and
up to 8m wide; locally such lenticular beds show a con-
vex-top boundary. As for Gcm facies, this lithofacies has
been well recognized in the upper part of Nocella
Conglomerates.

LLiitthhooffaacciieess  GGhh  ––  HHoorriizzoonnttaallllyy  ssttrraattiiffiieedd  ccllaasstt--ssuuppppoorrtteedd
ccoonngglloommeerraattee

Pebble to fine cobble-size clasts in this facies are
subangular to subrounded; they are  moderately to well
sorted with a clast-supported texture (Fig. 5). Well deve-
loped bedding and horizontal stratification is ubiquitous;



89The Nocella Conglomerates ...

pebble-size clasts show
a local well developed
a(t)b(i) fabric mode.
Imbrication and cluster
bedforms indicate paleo-
flow directions toward
WNW. Conglomerate
beds are usually normal
graded (Fig. 5); medium
to coarse sand matrix is
usually present but open
framework conglomerate
beds also occur (Fig. 5).
Local beds exhibit bimo-
dality both (Fig. 5) in the
lower and in the upper
band of each bed - tex-
tural inversion of Nemec
& Steel (1984) and Steel
& Thompson (1983).
These conglomerates
occur in laterally conti-
nuous beds that can be
traced for at least 20m;
basal contacts are
usually sharp and pla-
nar, but local scour sur-
faces may be observed.

These sheet-like units, tipically few dm thick (up to
40cm), set up multistory units up to about 4m thick. This
lithofacies is interbedded with Gcm and Gci lithofacies,
but is well developed also in the middle part of the
Nocella Conglomerates.

LLiitthhooffaacciieess  GGpp  ––  PPllaannaarr  ccrroossss--bbeeddddeedd  ccllaasstt--ssuuppppoorrtteedd
ccoonngglloommeerraattee

This facies consists of subangular to subrounded
pebbles. The clasts are moderately to well sorted and
characterised by a clast-supported texture. Well develo-
ped planar cross-stratification occurs; the foreset beds,
up to 15cm thick, consist of alternating fine and coarse
pebbles without any signs of rhythmic organization. Dip
azimuth of the foreset beds is toward SSE; dip angle
range from few degrees up to 13°. Foreset beds appear
to be ungraded. Sandy matrix is scarce but usually pre-
sent; some local foreset beds have an open framework.
These conglomerates occur in laterally continuous tabu-
lar units, ranging from 50 to 110cm in thickness, with
internal scour surfaces. Basal contacts are sharp and
non erosive; top contact shows a local convex-up boun-
dary (Fig.6). This lithofacies occurs in the middle part of
the Nocelle Conglomerates and grade laterally into Gh
lithofacies.

LLiitthhooffaacciieess  GGtt  aanndd  GGtt11  ––  TTrroouugghh  ccrroossss--ssttrraattiiffiieedd  ccoonngglloo--
mmeerraattee

Trough cross-stratified conglomerate occur as sin-
gle sets ranging from 0.6m to 1,5m deep and from 1,2m
to 7.4m in width. Basal scours affect both the conglome-
rate  facies and sandy ones; channel margins are gen-
tler in slope with increasing channel width The bigger
ones occur in the middle part of the Nocella
Conglomerates (Fig. 7A). This facies is developed in
pebble size clasts, subangular to subrounded; they are
moderately to well sorted with a clast-supported texture.

Fig. 5 - Set of clast-supported conglomerates with disorganized
fabric (Gcm facies) overlay normal graded, horizontally strati-
fied conglomerates (Facies Gh). Note also the poor degree of
rounding of the clasts. Paleoflow is obliquely into the face and
to the left.

Strati di conglomerati massivi, clasto-sostenuti (facies Gcm)
ricoprono conglomerati stratificati organizzati in unità normal-
mente gradate (facies Gh). Si può notare lo scarso grado di
arrotondamento dei clasti. I paleoflussi sono obliqui e diretti
verso sinistra.

Facies Facies Sedimentary Intepretation
code structures

Gcm Massive, clast None or weak Pseudoplastic cohesionless
supported gravel grading debris flow or high sediment-

concentration flood flows

Gci Clast-supported Inverse grading, Clast-rich debris flow or
gravel locally imbrication hyperconcentrated flood-flows;

filling of broad, sheet-like channels

Gh Clast-supported, Horizontal bedding, Accreditionary units longitudinal
well bedded gravel imbrication bars

Gt Gravel, stratified Trough cross-beds Minor channel fills

Gt1 gravel, stratified Low-angle and/or Rapid scour fills by high-
horizontal bedding concentration flood-flows

Gp Gravel, stratified Planar cross-beds Transverse accretion units of bars

Sh Coarse sand, many Crude horizontal Deposition from heavily
be pebbly lamination, locally sediment-laden flows during

massive waning floods above bars

Table 1 - Description and interpretation of sedimentary facies adapted from Bridge (1993) and Miall (1996)



Trough fill consists of non rhythmic alternating fining
upward and ungraded low angle sets (Gt lithofacies
Fig.7A); their thickness is up to 15cm and they dip of
about 10°. 

Locally lag deposits of coarser grain size (up to
fine boulders) grading upward into Gci lithofacies occur
above a bowl-shaped, erosional bases of trough sets
(Gt1 lithofacies; Fig. 7B). Through fill consists also of
stacked sets of Gh lithofacies. Just once (Fig. 7C) well
developed foreset beds dipping north-westward was
observed overlying Gt1 lithofacies; these beds may be
considered as Gp lithofacies and grade upward into Gh
lithofacies. 

LLiitthhooffaacciieess  SShh  ––  HHoorriizzoonnttaallllyy  ssttrraattiiffiieedd  ssaannddssttoonnee
This lithofacies consists of sand to granule size

clasts, with a local occurrence of isolated out-sized cla-
sts (a-axes>5cm). It is organized in lenses and/or
wedge-shaped units locally up to 15cm thick and over
7m extended. Locally they show crude horizontal stratifi-
cation. Massive texture was also observed. Sandy
facies usually rest on Gh lithofacies.

33..22  FFaacciieess  aassssoocciiaattiioonnss  iinntteerrpprreettaattiioonn  
Lateral and vertical facies associations, paleocur-

rent and coarse-grained texture suggest that the Nocella
Conglomerates was deposited in a high velocity stream.

On the basis of comparisons with the degree of roun-
ding shown by other Pleistocene alluvial units of the

90 A. Amato - G. Robustelli

Fig. 6 - Middle part of the Nocella Conglomerates: one large-
scale sets of planar cross-stratified conglomerates (Gp facies)
overlain and underlain by horizontally stratified conglomerates
(Gh facies).

Porzione intermedia dei Conglomerati di Nocella: si nota un
intervallo a stratificazione incrociata-planare (facies Gp) inter-
calato in conglomerati a stratificazione orizzontale (facies Gh).

Fig. 7 - Trough cross-stratified conglomerates: A – Example of
large-scale Gt facies cut into Gh ones near the middle of the
Nocella Conglomerates. B – Oblique view of trough cross-stra-
tified conglomerates (Gt1 facies), underlying horizontally strati-
fied conglomerates (Gh facies). C – Oblique view of trough
cross-stratified conglomerates (Gt1 facies), showing coarse lag
above scour surface; trough fill consists of alternating fine and
coarse pebble foresets (Gp facies) characterized by a decrea-
se of dip angle with a gradual transition into Gh facies.

.Conglomerati organizzati in unità canalizzate: A – Esempio di
unità canalizzata (facies Gt) che incide conglomerati a stratifi-
cazione orizzontale (facies Gh) nella porzione intermedia dei
Conglomerati di Nocella. B – Vista obliqua di conglomerati
organizzati in unità canalizzate (facies Gt1), cui seguono in suc-
cessione conglomerati a stratificazione orizzontale (facies Gh).
C – Vista oblique di conglomerati organizzati in unità canalizza-
te (facies Gt1), in cui si osservano i depositi residuali basali
poggianti sulla superficie di erosione; il riempimento è costituito
da un’alternanza di ghiaie fini e grossolane a stratificazione
incrociata-planare (facies Gp) e di cui gli strati sono caratteriz-
zati da una riduzione della pendenza e da un graduale passag-
gio alla facies Gh.



area, we can estimate that the river reach upstream  of
Nocella outcrop, i.e. the feeding stream, was at least a
2-3 kilometres long.

Two facies associations have been distinguished,
and their depositional systems have been reconstructed
accordingly as follows: 

FFaacciieess  aassssoocciiaattiioonn  11 is restricted to the middle
portion of the Nocella Conglomerates. Horizontally stra-
tified conglomerates (Gh lithofacies) is the most com-
mon facies typically forming sheet-like units.
Subordinate lithofacies are represented by planar cross-
stratified conglomerates (Gp lithofacies). Minor lithofa-
cies consist of trough cross-stratified conglomerates (Gt
lithofacies) and horizontally stratified sandstones (Sh
lithofacies). 

Contacts between Gh and Gp lithofacies are
usually sharp and flat, but locally they are slightly scou-
red. These conglomeratic lithofacies occur in laterally
continuous tabular beds that can be traced for several
meters.

The dominance of horizon-
tally stratified conglomerates
with local internal scour indica-
tes that high-energy tractional
processes were involved, as the
coarse-grained texture and the
absence of fines also suggest.
In particular, the dominance of
tabular conglomerate sheets
indicates that deposition was
laterally extensive; although the
occurrence of broad and shallow
channels is shown by  internal
erosive surfaces. As a whole
this facies is interpreted as
being formed by deposition and
migration of bars in a high-
energy gravel-bed river (Miall,
1977; Rust, 1978; Collinson,
1986; Miall,1996). Evidence for
stream flow processes includes
also clast-supported framework,
a(t)b(i) fabric mode and lenticu-
lar trough cross-stratified con-
glomerates, the latter occur as
minor lithofacies. The channel-
like bedforms consist of few
local scours over 1m deep and
5m wide. The cross-cut relation-
ship with Gh lithofacies suggest
that trough-cross stratified con-
glomerates may be representati-
ve of channels cutting across
bars top and/or front during fal-
ling water, followed by gradual
infilling of the scours. 

The southern tip of the
western measured section
represent the one and only
place at which the continuity of
exposure allows us to attempt a
hierarchical classification of the
depositional units and bounding
surfaces. However, even there
the impossibility to look frontally

at the whole exposure prevents us from getting reliable
results. Nevertheless, it is noteworthy that horizontally
stratified conglomerate grade laterally into gently incli-
ned Gp lithofacies (Fig. 8; Tab. 2), which can be inter-
preted as lateral accretion of gravel sheets on inclined
surfaces, indicating a margin of a macroform (Tab.2;
element LA sensu Miall, 1985; 1988). The overlying and
underlying horizontally stratified conglomerate have
been interpreted as indicative of element GB of Miall
(1985, 1988). Therefore the presence of element GB
(Tab.2) and the occurrence of locally interbedded ele-
ment LA (Tab.2) may be interpreted, according to Miall
(1996), as representative of a shallow to relatively deep,
gravel-bed braided river. An architectural model of this
type of river may be considered the model 3 of Miall
(1985)

FFaacciieess  aassssoocciiaattiioonn  22 is restricted to the upper por-
tion of the Nocella Conglomerates. The most common
facies is the horizontally stratified conglomerates (Gh),
typically forming sheet-like units. Subordinate lithofacies

91The Nocella Conglomerates ...

Fig. 8 – Oblique view (A) and interpretation of the photograph (B). For element and facies
codes see tables 1 and 2. Circled numbers refer to the order of bounding surface. Circled let-
ters are architectural elements. For element and facies codes see Tables 1 and 2. 

Vista obliqua (A) ed interpretazione (B) di una porzione della sezione S1. Per le sigle delle
facies e degli elementi architettonici vedi le tabelle 1 e 2. I numeri si riferiscono all’ordine gerar-
chico delle superfici che limitano gli elementi architettonici (lettere cerchiate). Le sigle delle
facies e degli elementi architettonici sono indicate rispettivamente in Tabella 1 and 2. 



are represented by massive conglomerates (Gcm litho-
facies) and inversely graded conglomerates (Gci lithoca-
cies). Minor lithofacies consist of trough cross-stratified
conglomerates (Gt and Gt1 lithofacies) and horizzontally
stratified sandstones (Sh lithofacies). Gp lithofacies was
not observed.

This association is characterized by stacked-
sheets of graded and massive clast-supported conglo-
merates. The sheet-like beds range from few centime-
ters up to 50 cm in thickness and can be traced over a
distance of several meters (see Fig. 3, upper part of
Nocella Conglomerates). The bases of the conglomera-
te sheet.-like bedforms are sharp and flat, but scour sur-
faces occur so lenticular units may be recognized. As
for the facies association 1, the dominance of horizon-
tally stratified conglomerates suggests that high-energy
traction-current processes were the main depositional
processes. Therefore this facies is interpreted as being
formed by migration of shallow and broad braided chan-
nels with abundant low-relief bars in high-energy gravel-
bed river. The lack of evidence of planar cross-beds (Gp
lithofacies), whose origin requires deep-water channel
(Bluck, 1979; Steel & Thompson, 1983; Kraus, 1984),
provides evidence of the shallow depth of the paleo-
channels. Clast-supported framework, a(t)b(i) fabric
mode and cluster bedforms are further evidences for
stream flow processes. 

The massive (Gcm) and inversely graded (Gci)
lithofacies suggest that depositional events were occa-
sionally of very high energy; in particular, according to
Shultz (1984) Gcm and Gci lithofacies can be conside-
red as depositional evidences of pseudoplastic debris
flow and clast-rich debris flow respectively; as also sug-
gested by Lowe (1982), Gloppen & Steel (1981) and
Nemec & Steel (1984), or representative of very high

sediment-concentration  dispersions (dilution of debris
flows) such as hyperconcentrated flood-flows (Pierson,
1980; Pierson  & Scott, 1985; Ridgway & DeCelles,
1993; Scott, 1988; Smith, 1986; Smith & Lowe, 1991;
Waresback & Turbeville, 1990). Todd (1989) suggests a
stream driven origin (high-density gravelly traction car-
pets) for the Gcm and Gci lithofacies; in particular Gci
lithofacies is representative of granular flows in which
during motion a dispersive pressure dominates (Lowe,
1982; Sohn et al., 1999; Todd, 1989). The massive,
structureless conglomerates represent the deposits of
cohesionless debris-flow (Smith & Lowe, 1991; Sohn et
al., 1999) dominated by frictional grain interactions in
which clast collision is hampered resulting in the lack of
inverse grading and clast imbrication.

The lenticular trough cross-stratified conglomera-
tes  consist of few local bowl-like channels less than 1m
deep and 5m wide. The local infillings consists of in-
channel deposition by high-magnitude flood-flows (Gt1
lithofacies, Figg.7B and 7C; Hein & Walker, 1977; Miall,
1977; Nemec & Postma, 1993; Jo & Chough, 2001); in
particular Gp lithofacies (Fig. 7C) may be interpreted as
cross-bedded conglomerates developing where chan-
nels debouche into pools (Ramos & Sopena, 1983).

As a whole we may interpret the laterally extensive
conglomerate sheets as elements GB (sensu Miall,
1985; 1988; Tab. 2) in which high energy flood-flow
deposits (Gcm and Gci lithofacies) are subordinate and
representative of broad, low-relief channel fill. Element
GB consists of three types of gravel tractions-current
deposits; Gh lithofacies predominates, whereas tha Gt
and Gt1 ones are very subordinate. The interbedded
lenses of horizontally stratified sandstones (Sh lithofa-
cies) may represent remnants of element SB due to
rapid deposition from heavily sediment-laden flows

92 A. Amato - G. Robustelli

Element and
Symbol

Horizontally
stratified sets
(GB)

L a r g e - s c a l e ,
planar cross-
stratified set
(LA)

Channel (CH)

S m a l l - s c a l e
scour fill (CH1)

Principal facies
assemblage

Gh, Gcm and
Gci interbedded

Gp, Gh

Any conbination

Gt, Gt1, Gp and
Gh

Bounding 
surfaces

Bound by erosi-
vely and accre-
tionary fourth-or-
der surfaces, pla-
nar to convex-up

Bound by fourth-
order surfaces
and internal third
-order surfaces
between accre-
tion elements

Bound with con-
cave-up, fifth-
order surfaces

Provide palaeo-
current of down-
stream accretion
directions. Asso-
ciated with con-
cave-up, fourth-
order surfaces

Description

Stacked sets of horizontally
stratified conglomerates; indi-
vidual sets, decimeters thick
and meters (up to 20 m) in
lateral extent, parallel strata.

Solitary set of planar cross-
stratified conglomerates dip-
ping about perpendicular to
paleocurrent direction; deci-
meters thick and meters in
lateral extent.

Lenticular unit with concave-
up, erosional base; up to 5m
thick and tens of meters wide.

Lenticular unit with concave-
up, erosional base; solitary
unit, decimeters to 1,2m thick
and meters wide.

Interpretation

Vertical aggradation and down-
stream migration of broad, low-
relief bars. Filling of broad,
sheet-like channels by deposition
from highly concentrated flows

Lateral accretion of bars with
internal re-activation surfaces

Filling of major channels

Filling of minor channels and
scours on bars

Table 2 - Description and interpretation of architectural elements adapted from Miall (1985, 1988, 1996) and Bridge (1993)



93The Nocella Conglomerates ...

during waning flood (Todd, 1989; Maizels, 1993; Jo &
Chough, 2001).

This kind of facies architecture, according to Miall
(1996), is consistent with a shallow, gravel-bed braided
river interpretation. The architectural model of this type
of river could be the model 2 of Miall (1985).

44..  DDIISSCCUUSSSSIIOONN

The sedimentologic and geomorphologic data
reported above allows us to propose a new and more
complete interpretation of the highly hanging clastic
deposits outcropping near to Nocella village, previously
interpreted as slope replacement breccia by Brancaccio
et al. (1979) and Cinque (1986). The detailed facies
analyses of the Nocella Conglomerates have documen-
ted an high-energy, gravel-bed fluvial setting with a
WNW-sloping paleoslope, the latter suggested by paleo-
current data. 

Facies association 1, although characterized by a
dominance of horizontally stratified conglomerates (Gh
lithofacies), consists also of laterally extended sets of
planar cross-stratified conglomerates (Gp lithofacies)
that grade laterally into the Gh one (lateral accretion of
gravel bars on inclined surfaces; element LA sensu
Miall, 1985; 1988). 

Facies association 2 is characterized by Gh litho-
facies with subordinate Gcm and Gci ones, and a lack of
planar cross-stratified conglomerates. The dominance of
laterally extensive gravelly sheets coupled with the
absence of Gp lithofacies suggests that flow depths
were more shallow than ones suggested by facies asso-
ciation 1.  

On the basis of comparisons with the sedimentolo-
gical features offered by the Pleistocene alluvial fan
deposits of the Pimonte area (Aucelli et al., 1996), a
confined alluvial fan interpretation may be proposed as
the Nocella Conglomerates consists mainly of stacked-
sheets of graded and massive clast-supported conglo-
merate, which can be traced over a distance of several
meters; in fact the gathered data are indicative of depo-
sition and migration of low-relief longitudinal bars in
shallow, high-velocity gravel-bed stream. But the lack of
other outcrops beside that of Nocella does not enable
us to definitely confirm this hypothesis as an abrupt
basinward facies transition may not be observed.
Although a vertical change from more distal to proximal
fluvial settings is suggested by both the disappearing of
macroforms interpreted as laterally accretion of gravel-
bars and the upward abrupt increase of high energy flow
deposits (Gcm and Gci lithofacies). 

In order to interpret the vertical change of the
facies associations within the Nocella succession, diffe-
rent factors can be considered. First of all the angular to
subrounded shape of the Nocella Conglomerates clasts
prove that slope deposits produced by Paipo fault scarp
retreat are poorly reworked by fluvial processes as the
absence of slope deposits interfingering with fluvial ones
suggest. A climatic factor could also be considered to
unravel the varying vertical facies association of the
Nocella Conglomerates: the river models deduced by
analysing the facies architecture may witness a decrea-
se of water discharge and/or an increase of sediment
supply. The abrupt transition from fluvial deposits to

slope ones should be due to Early – Middle Pleistocene
re-activation  of the southern segment of the Scrajo-
Vettica fault zone which could have beheaded the upper
reach of the catchment. Conversely, the same abrupt
transition could also be due either to a sudden lateral
(south-westward) shifting of the watercourse or to the
advancing of the debris slope after a phase of downcut-
ting.

Moving north-westward suspended at about 600 –
650 m a.s.l. stand the S. Maria del Castello II order relic
(Figg. 2 and 3) and a small erosional hanging terrace
both sealing the Scrajo – Vettica fault. Also the Paipo
breccias, located south-eastward of Nocella site, seal
the older segment of the Scraio-Vettica fault zone.
These erosional and depositional landforms have been
interpreted to belong to the same geomorphological
stage, apart from the uppermost slope deposits which
could also be more recent, in the case of a preceeding
phase of downcutting or tectonic behading of the upper
catchement.  

As a whole it was concluded that the paleo-
morphology of the study area, at the time of the Nocella
Conglomerates deposition, was quite different from the
modern one. The source area of the Nocella
Conglomerates has to be related to a small river catch-
ment nested into a nowadays lost  morphostructural
high located east-southeastward of the study area (Fig.
2). This topographic high had to include also the moun-
tainous area that fed the clastic infilling of the Agerola
karstic basin, whose western deposits show a clear dip
towards northeast (Brancaccio et al., 1976; Cinque,
1986). Moreover, the gentle landscape of S. Maria del
Castello site settled at the footslope of the Scraio-
Vettica Maggiore fault scarp, represents the WNW part
of a low relief landscape, that we interpret as part of the
WNW-sloping paleoslope of the river basin in which the
Nocella Conglomerates were deposited. 

In order to better clarify the chronological frame of
the II order palaeosurface and its correlative deposits of
Nocella Formation we summarize the whole geo-
morphological evolution of the Sorrento peninsula. 

The oldest geomorphological stage is recorded by
the formation of the I order palaeosurface (Fig.9-I)
There follows a  phase of block-faulting driven by NE-
SW direction of extension led to the fragmentation of
this landscape, well documented by the structural analy-
sis carried out on the Scraio Vettica fault (Fig. 9-II;
Caiazzo et al., 2000). After the Early Pleistocene acti-
vity, the II order palaeosurface developed with a
base–level ranging between  600 – 750 m a.s.l.(Fig. 9-
III). As reported by Caiazzo et al., 2000 part of the
Scraio Vettica fault zone was reactivated during Early
Pleistocene – Middle Pleistocene p.p. and driven by
NW-SE direction of extension; the only southern seg-
ment coinciding with the present structural sea-cliff
between Positano and Vettica towns moved during this
more recent phase. After the Early Pleistocene – Middle
Pleistocene p.p. tectonic phase, the relics of the II order
landscape were suspended, the Nocella fm. and the
Paipo breccias were truncated,  and, seemingly, whole
portions of the II order landscape (southern portions of
the area) which had to represent the source area of
these clastic units, were definitively drowned (Fig. 9-IV).
As a consequence, the age of  the II order palaeland-
scape should be Early Pleistocene. 



55..  CCOONNCCLLUUSSIIOONN  

We have reconstructed the Early Pleistocene
palaeolandscape of a portion of the eastern Sorrento
Peninsula by detailed geomorphologic survey and sedi-
mentological analysis of the Nocella Formation.

On the basis of our data this hanging succession,
previously interpreted as entirely composed of slope
breccias, consists of a basal portion (about 90m thick) of
alluvial deposits (Nocella Conglomerates), overlain by
stratified slope deposits (Nocella breccias). The Nocella
Conglomerates can be referred to the geomorphologic
stage immediately successive to the tectonic fragmenta-
tion of the I order palaeosurface (Pliocene - Early
Pleistocene in age), which is the oldest geomorphologic
element of this region (Fig. 9). At that time the block-
faulting caused the deepening and widening of the Gulf
of Salerno and allowed the Sorrento peninsula to be
further uplifted; in the meanwhile the width of the penin-
sula itself was progressively reduced and the Agerola
tectonic depression was created. During this period the
peninsula was towards the South still wider and lower in
elevation than today. Subsequently a period of relative
tectonic stability occurred and a new generation of low
relief landscape (II Order Palaeosurface) was formed.
Uplifted remnants of the II Order palaeosurface occur in
several places at elevations from 500 m to 800 m (Fig.
2). In fact the Agerola graben, whose southern rim at
present is open towards the South, by that time was

entirely closed and received clastic imputs also from the
southern reliefs. These ones had to include also the
mountainous area into which a small river catchment
had to be nested and fed the clastic infilling of Nocella
palaeovalley; the sedimentologic analysis of the Nocella
Conglomerates also suggests a source area which
extended for some Km to the South-East. The palaeo-
valley had to be flanked by Mt. Tre Calli to the North-
East and some other reliefs of similar height (higher
than about 800m in any case) to the South-West. These
reliefs were part of  morphostructural high which close
towards the South and fed the alluvial clastic infilling of
the Agerola depression. Furthermore, the S. Maria del
Castello II order surface has been interpreted as the
basinward portion of the low gradient paleoslope on
which the Nocella river was flowing. Other small han-
ging concave up footslopes (erosional landforms beside
Moiano, Ticciano and Massaquano settlements), have
been interpreted as erosional and depositional
landforms connecting the Scrajo-Vettica fault scarp to
the Nocella river valley.

After the development of the the II Order
Palaeosurfaces, the study area was affected by a tecto-
nic phase driven by a NW-trending direction of exten-
sion which allow NE- trending fault scarps to be formed
(Caiazzo et al., 2000). According to the Authors this tec-
tonic event may be ascribed to the beginning of the
middle Pleistocene. Furthermore, the southern segment
of the Scrajo-Vettica fault zone was reactivated as tran-

94 A. Amato - G. Robustelli

Fig. 9 - Main stages of the morphotectonic and the drainage evolution of the study area. C marks S.Maria al Castello; NN marks Nocella
site; FF marks Mt. Faito; TTPP marks S. Angelo a tre Pizzi; TTCC marks Mt. Tre Calli; A marks Agerola; I, II, III; IV modified from Caiazzo et
al. (2000); • • : beheaded valley; � �: relic valley;             �: river capture.
Principali tappe dell’evoluzione morfotettonica e del reticolo idrografico. Le lettere CC, NN, FF, TTPP, TTCC, AA, indicano rispettivamente le loca-
lità di S.Maria al Castello, il sito studiato di Nocella, M. Faito, M. S. Angelo a tre Pizzi, M. Tre Calli ed Agerola. I, II, III e IV modificate da
Caiazzo et al. (2000); • •: valli tronche;� �: valli relitte; �; catture fluviali.



95

sfer fault. The peninsula was progressively reduced by
block faulting that affected its southern flank which
enlarged the contiguous Gulf of Salerno and drawing
the present-day coastal profile.

AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS

The authors wish to thank Prof. A. Cinque for the
helpful field discussions and the useful comments on
early draft of the manuscript. This article benefited from
helpful review and suggestions by L. Brancaccio and M.
Sagri. 

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96 A. Amato - G. Robustelli

Ms. ricevuto il 26 marzo 2002
Testo definitivo ricevuto il 28 maggio 2002

Ms. received: March 26, 2002
Final text received: June 28, 2002