e Almopia Speleopark is located in the inner-mountain
Almopia basin, in Northern Greece (Macedonia), 120
km northwest of essaloniki and 2 km from the Kato
Loutraki village, on the slopes of the Voras Mt. (2524 m
high), one of the highest mountains of Greece. A number
of caves, opened by the downcutting of the ermopota-
mos River, are situated in the V-shaped Nicolaou valley
of the Speleopark (g. 1).
Speleological research in the Loutra Arideas area
started in 1990, when the late speleologist K. Ataktidis
reported nding of cave bear bones, that where dug up
illegally by treasure hunters in Bear Cave. Due to the
great paleontological interest the rst excavation cycle
was launched in 1992 by the Geology School of Aristotle
University, essaloniki (AUTH) (E. Tsoukala), under
the supervision of the Ephorate of Speleology and Pa-
leoanthropology (ESP) of the Ministry of Culture, and
in cooperation with archaeologist Prof. G. Chourmouzi-
adis, and of the late Prof. Eitan Tchernov (University of
Jerusalem). e excavations continued in 1993-1994 in
cooperation with ESP (Dr. E. Kambouroglou). In 1996
and since 1999 the excavations have been carried out by
the AUTH, the ESP, and in co-operation with the Vi-
enna University (Profs G. Rabeder, S. Verginis and their
team). e palaeontological specimens from Bear Cave
recovered in these excavations can be attributed to Ursus
ingressus RABEDER, HOFREITER, NAGEL & WITHALM,
2004 and to the associated fauna including spotted cave
hyena, lion, leopard, wolf, fox, badger, mustelids, artio-
dactyles and micromammals, of Late Pleistocene age
(T, 1994; T et al., 1998; T et
al., 2001; T R, 2005; C,
2001; C et al., 2001; P et al., 2005).
ere are also caves in both sides of the valley with ar-
cheological remains, mainly with Neolithic and Byzan-
In 1990, the late K. Ataktidis also made the rst docu-
mentation of the caves and organized the rst explora-
tion of the Speleopark. During this expedition prelimi-
nary geological (Dr. Tsamandouridis, unpublished data)
and paleontological (Tsoukala, unpublished data) results
were reported. e late speleologist J. Ioannou, member
of the rst exploration, noted that the Loutra Arideas
area is of high scientic and speleological interest; there-
fore he suggested that it could be the rst speleological
park (“Speleopark”) in Greece. e next researchers sup-
ported his idea and it is well accepted now. In 2005, the
speleological research continued. New discoveries and
photographic documentation, surveys and observations
enlarged the scientic knowledge of the area (L-
, 2005). Today the speleological research is progress-
ing well with the aim of completing the previous work as
much as possible and to contribute to the palaeontologi-
cal research in the area.
Scientic Annals, School of Geology
Aristotle University of essaloniki (AUTH) Special volume 98 33-40 essaloniki, 2006
ALMOPIA SPELEOPARK PELLA, MACEDONIA, GREECE:
MORPHOLOGY-SPELEOGENESIS OF THE CAVES
Abstract: In the present study the morphology of Almopia Speleopark caves is described in order to discuss
preliminarily their speleogenesis in relation to the hydrogeological zones. At least two phreatic phases seem
to exist with respect to the observed speleogens. e presence of solution ceilings, cupolas, ridges, pendants,
abruptly ending passages and the horizontal morphology of the caves suggest that speleogenesis was due
to slowly convecting water bodies. As an exception, some caves contain scallops or other phreatic features
that developed by forced ow along a pressure head. e former pattern of speleogenesis was related to the
presence of thermal ascending water in the area, while the latter is related to the downcutting of the er-
Key words: Almopia Speleopark, Aridea, Macedonia, Greece, speleogenesis, cave morphology.
School of Geology, Aristotle University, 54 124 essaloniki, firstname.lastname@example.org
e general area is situated near the geological boundary
between the Almopia Zone to the east and Pelagonian
Zone to the west (M, 1968; M, 1976).
It consists of Mesozoic metamorphic and sedimentary
rocks, and more precisely the Nicolaou valley consists of
Maastrichtian limestones of the Almopia zone. A NW-SE
striking, ore-bearing fault zone and the ENE-WSW strik-
ing Loutraki Fault dominate the general area tectonically.
e latter has a length of more than 10 km bounding the
Aridea basin against the Voras Mt. (2524 m) (M-
, 1976; E, 1977; C,
In the general area of the Almopia Speleopark on the
Pelagonian massif, three uplied denudation surfaces
and one or two piedmont surfaces have been identied
by P K (1989). e former three sur-
faces were established in periods of a warm and humid
climate prior or during the Neogene. e latter surfaces
were formed in periods of warm and semiarid climate
during the Villafranchian - Villanyian, or in glacial/inter-
glacial climates during the Pleistocene. e entire north-
ern part of the Pelagonian massif (Macedonia) has been
uplied at higher rates than its southern section. Above
the caves there is a notable erosional surface, approxi-
mately at 700 m a.s.l. where the old Ano Loutraki village
is located. According to the description by P
K (1989) of the erosional surfaces of the Pelago-
nian massif, this surface is probably an Early Pleistocene
Neotectonic activity of the Loutraki fault uplied
the Voras Mt. and the area of the Speleopark. As a re-
sult intense down-cutting of the ermopotamos River
occurred that formed the V-shaped Nikolaou valley and
lied the caves from the phreatic to the vadose zone suc-
Furthermore, a group of thermal springs exists due
to the neotectonic activity and to the volcanism in the
broader region (M, 1976; V,
2002; P, 1990). M (1976) states that
the origin of the travertine in the Loutra area, as well
as at other localities nearby, is also due to these thermal
34 Sci. Annals, Geol. School, AUTH, special vol., 2006
Figure 1. Le: Map of Greece with the Almopia Speleopark (LAC: Loutra Arideas Caves) and a view of the Nicolaou valley with the
list of the caves on both sides. Right: geological sketch-map of Almopia (based on M, 1968).
LAZARIDIS, G. 35
springs either being active today or in the past. P
(1990) calculated that the water rises from a depth of 600
m and its temperature at this depth ranges from 150 to
180°C. Today springs are located from 360 to 390 m of al-
titude. eir temperature varies between 30 and 37.5°C.
e same researcher states also that the Na+, K+ and SO4
concentrations decreased in correlation with a lowering
of the spring water temperature, because possibly of their
precipitation during their mixing with cooler water.
MORPHOLOGY AND SPELEOGENS
OF THE CAVES
e Almopia Speleopark consists of six caves and four
rock-shelters of similar morphology, the altitudes of
which ranges between 460 m to 560 m a.s.l. (pl. 1). Addi-
tionally some small “isolated” chambers and many karst
conduits occur as well. Presently they are “dry caves” in
the vadose zone.
e caves described here as rock-shelters (pl. 2.1) are
remnants of karst caves intersected by surface erosion.
For this reason they developed as small chambers with
many small conduits. Usually they contain a lot of break-
e larger caves have a maze-like pattern, structur-
ally guided by joints. Maze caves can develop only if the
growth rate is similar along many alternate ow paths.
e maze pattern in general presents a variety of types.
Six dierent types of linestone caves are dierentiated:
two branching types (curvilinear, rectilinear) and four
maze types (anastomotic, network, spongework, rami-
form) (P, 2000; 2005). e plan morphology of the
Almopia Speleopark caves reminds of ramiform mazes.
is kind of plan pattern is due to local boosts in the wa-
ter aggressiveness. Generally angular connections domi-
nate where joints and faults are the principal structural
guides of the conduits in contrast to curvilinear connec-
tions that dominate where the conduits develop primarily
along bedding planes (F, 2000). e Almopia Spele-
opark caves present angular connections that indicate
the signicance of fracture control. However, they also
show a ramiform pattern that illustrates the importance
of the bedding partings in contrast to network types that
show fracture control. e former refers mainly to the
major passages of the caves. e latter is noticed in some
large halls, in some small passages and in places where
boneyard morphology (pl. 2.10) is observed. Generally
the caves that developed on the northern slope represent
large halls, except for the linear passages along joints, in
contrast to the caves of the southern slope where large
halls are absent. Large halls, connected by small ‘‘win-
dows’’ are predominant in Bear Cave, Antarton Cave,
Gremos Cave and Varathron Cave.
e predominant strike of the cave passages is NW-
SE and NE-SW. e majority of the caves have more than
one entrance developed by intersections of passages by
Cave genesis in general can occur either below the
ground water table (i.e. in the phreatic zone) or in the
unsaturated zone above the water table (i.e. in the va-
dose, where cavities are mostly lled with air). Both
zones leave characteristic micro- and mesoscale mor-
phological elements known as speleogens, that can be
used to reconstruct the speleogenetic history of a cave
or a cave area. In the case of the Almopia Speleopark,
morphological indicators suggest that the bulk of the
cavities developed under phreatic conditions and that
vadose processes later altered the initial morphology.
e phreatic origin of the caves (Kempe, pers. com.)
is indicated by the following morphological elements
(according to K, 1970; K et al., 1975; B,
1978; W D, 1989; L L,
2000; W W, 2000; L, 2005; K
et al., 2006):
1. Solution ceilings (Laugdecken) either at or concave
formed by slowly convecting water bodies (pl. 2.2).
2. Walls sculptured by cupolas that grade downward
into sloping side walls (facets) (pl. 2.2).
3. Bedrock ridges that separate the halls or interrupt the
passages (pl. 2.3).
4. e presence of elliptical (lenticular) and symmetrical
cave passages (in cross sections) that are controlled
by high angle joints or by the intersection between
two planes respectively (pl. 2.4; 2.7 and 2.9).
5. Many solution pockets that are present at the roof of
some caves of the Speleopark; these are created by
mixing corrosion along joints where water emerges
into a passage lled with water of a dierent chemis-
try (pl. 2.5 and 2.6).
6. e presence of ceiling half-tubes, i.e. a channel in the
ceiling of descending elliptical passages with a semi-
7. Scallops on ceilings and walls that develop by solution
in a turbulent ow of groundwater lling the passage
(pl. 2.11). ey are absent in Bear Cave, Antarton
Cave and Gremos Cave, while there is one passage
with scallops in Varathron Cave. On the other hand,
the caves of the southern slope contain abundant
scallops that indicate a S-N ow direction from the
caves outward to the river. On the contrary the scal-
lops of Varathon Cave and Pyromachikon Cave show
the same ow direction but from the river inward to
8. Pendants that are remnants from removal of interven-
ing rock through eddy dissolution (pl. 2.8 and 2.14).
36 Sci. Annals, School of Geology, AUTH, special vol. 98, 2006
Almopia Speleopark; surveys of the caves. Ground plans: 1a. Varathron Cave; 2. Antarton Cave; 3. Pyromachikon Cave; 4. Gram-
maton Cave; 5. Gremos Cave; 6. Z-Cave; 7. Bear Cave (based on K C, 1999); 8. Avra Cave;
9. Plotsa Cave; 10. Keramikon Cave; 1b. Cross section of the main chamber of Varathron Cave.
LAZARIDIS, G. 37
Almopia Speleopark: 1. e “rock-shelter’’ morphology of the Speleopark Caves (Z-Cave); 2. Sculptured ceiling in Antarton Cave
by slowly convecting water bodies (Kempe, pers. com.); 3. Bedrock ridge that separates two chambers of the Bear Cave; 4. Elliptical
phreatic passage in Varathron Cave; 5. Solution pocket along a fracture; 6. A fracture guided group of pockets; 7. Elliptical phreatic
passages that end abruptly (Avra Cave); 8. Pendants of more than 1.5 m length (Bear Cave); 9. Phreatic passage at the higher en-
trance (520 a.s.l.) of Varathron Cave; 10. Boneyard morphology (Bear Cave); 11. Scallops; 12. Keyhole passage (Keramikon Cave);
13. Detail of the phreatic coating that cover the passage of the higher entrance of Varathron Cave; 14. Pendants of approximately
0.5 m of length in Avra Cave.
38 Sci. Annals, School of Geology, AUTH, special vol. 98, 2006
According to the presence or absence of these morpho-
logical elements, the initial development of the caves oc-
curred in the phreatic zone. Once the caves drained because
of the regional upli, changes in the vadose zone followed:
1. e deposition of the speleothems as a process that
takes place in airlled caves. e inclined passage
of the higher entrance of Varathron Cave is the only
place at the Speleopark caves, where phreatic speleo-
them coating on the passage walls has been observed
(pl. 2.9 and 2.13).
2. e lling of the caves with uvial sediments. ese
sediments are well studied in Bear Cave. e domi-
nant presence of Ca-Mg rich metamorphic minerals
(clinozoisite, tremolite, talc, chlorite/vermiculite) in
the ne-grained sediments of the cave oor is indica-
tive of the composition of the weathering products of
the parent rocks of the broader drainage basin, which
have been weathered. e absence of smectite and
kaolinite indicates that the sediments have not been
transported a long distance (T, 1998).
e allochthonous origin of the cave sediments is
recognised in general by the presence of non-carbon-
3. Keyhole passages occur only in Keramikon Cave that
represent the shi from the phreatic to the vadose
conditions. is type of passages results in the com-
bination of a symmetrical phreatic tube and a vadose
canyon (pl. 2.12).
4. Post-phreatic breakdown modied walls and ceilings
that lose their smooth surfaces, replacing it with a
more angular morphology, and obstructing the oor
by large blocks, diminishing the cross section of the
DISCUSSION - CONCLUSION
At least two phreatic phases must have occurred because
of the observed morphology and the presence or absence
of the corresponding speleogens (tab. 1). e presence
of solution ceilings, cupolas, bedrock ridges, pendants,
abruptly ending passages and the overall horizontal de-
velopment of the caves suggest the dominant phase of
speleogenesis was due to slowly convecting water bodies
in the phreatic zone. is morphology is characteristic
for Bear Cave, Antarton Cave, Gremos Cave and Varath-
ron Cave. ermally ascending water most probably was
responsible for the formation of the caves at this location.
Additionally, all caves occur in a relatively small area,
where even today thermal springs occur. As an exception
some of them contain abundant scallops or some other
phreatic features that are developed by forced ow along
a pressure head. Only these caves or passages might cor-
relate with a base level of the incising valley.
Almopia Speleopark. Morphology and location of the caves. Summary table.
Southern (S) or Northern (N) slope N N N S S N N N N N S
Altitude (m) 540 540 500-
520 460 494 536 541 560 540 537 570
Entrances 1 2 3 2 4 1 2 3 1 1 1
Solution ceilings + + + - - - - - - - -
Facets + + + - - - - - - - -
Bedrock ridges + + + - - - - + - - -
Elliptical & symmetrical passages + - + + + + + + + - -
Ceiling half-tubes - - - - + - - - - - -
Scallops - - + + + + - - - - -
Pendants + + + + - - - - - - -
Keyhole passages - - - - + - - - - - -
Phreatic speleothems - - + - - - - - - - -
Breakdown + + + - + - - + - + -
False-oors + + - - + - - + - - -
LAZARIDIS, G. 39
For the reason these two conditions above never hap-
pen simultaneously, a degeneration of the caves is pos-
sible. e development by convection is a deep-seated
method of speleogenesis that may have taken place before
the neotectonic activity in the area; therefore it probably
took place before the formation of the erosional surfaces.
While downcutting, took place near-surface groundwater
or surface water could have entered the caves, thereby by
passing the surface stream under pressure and re-sculp-
turing some of the walls under turbulent ow.
e predominant vadose modications are the lling
of the caves by sediments and the breakdown. Further-
more, the solutional or erosional vadose features present
a minor development.
Acknowledgments: I wish to express my sincerest thanks to
Professor Stephan Kempe, Darmstadt, Germany, for his guid-
ance, his valuable help and advice. Also I would like to thank
Ass. Prof. Evangelia Tsoukala for her support during every step
of this work and speleologist †Kostas Ataktidis - director of the
Physiographical Museum of Almopia - for his help during my
stays in Loutra.
BÖGLI, A., 1978. Karsthydrographie und Physische
Speläologie. Springer Verlag, 292 pp., Heidelberg.
CHATZIDIMITRIADIS, E. A., 1974. Die Problema-
tik der Erwärmung von ermalquellen und ihre
Zusammenhänge zu den geologisch-tektonischen
Verhältnissen ihrer Umgebungen anhand von zwei
Beispielen, nämlich der Heilquelle von Ano Loutraki
bei Aridea West Mazedonien und von Trajanoupolis
West rakiens.- Annals Fac. Phys. & Mathem., Univ.
essaloniki, 14: 113-128.
CHATZOPOULOU, K., 2001. Contribution to the study
of Quaternary micromammals and the stratigraphy of
the Cave A from Loutra Aridéas (Pella, Macedonia,
Greece).- Postgr. thesis (unpubl.), Aristotle Univer-
sity, essaloniki (in Greek).
CHATZOPOULOU, K., VASILEIADOU, A., KOLIADI-
MOU, K., TSOUKALA, E., RABEDER, G. & NAGEL,
D., 2001. Preliminary report on the Late Pleistocene
small mammal fauna from Loutraki Bear-cave (Pella,
Maced., Greece).- Cadernos Lab. Xeolóxico de Laxe,
26: 485-495, Coruña.
ELEFTHERIADIS, G., 1977. Study of the volcanic rocks
in South Almopia.- Ph.D esis Aristotle University
of essaloniki, 173 pp.
FORD, C. D. 2000. Speleogenesis under unconned set-
tings.- In: KLIMCHOUK, B. A., FORD, C. D., PALMER,
N. A. & DEYBRODT, W
., eds. “Speleogenesis. Evolution
of karst aquifers”. National Speleological Society: 319-
324, Huntsville, Alabama, U.S.A.
KAMBOUROGLOU, E. & CHATZITHEODOROU, TH.,
1999. Geomorphological changes and sedimentation
of the A cave (Agiasma) of Loutraki (Pella, Macedo-
nia, Greece).- Proc. 5th Congr. Greek Geographical
Society: 83-93, Athens (in Greek).
KEMPE, S., 1970. Beiträge zum Problem der Speläogen-
ese im Gips unter besonderer Berücksichtigung der
Unterwasserphase.- Die Höhle, 21/3: 126-134.
KEMPE, S., BRANDT, A., SEEGER, M. & VLADI, F.
1975. “Facetten” and “Laugdecken”, the typical mor-
phological elements of caves developing in standing
water.- Ann. de Spéléologie, 30/4: 705-708.
KEMPE, S., ALMALABEH, A., ALSHREIDEH, A.,
HENSCHEL, H.-V., 2006. Al-Daher Cave (Bergish),
Jordan, the rst extensive Jordanian limestone cave:
A convective Carlsbad-type cave?- J. Cave and Karst
Studies, 68 (3): 107-114.
LAURITZEN, S.-E. & LUNDBERG, J., 2000. Solutional
and erosional morphology. -In: KLIMCHOUK, B. A.,
FORD, C. D., PALMER, N. A. & DEYBRODT, W
“Speleogenesis. Evolution of karst aquifers”. National
Speleological Society: 408-426, Huntsville, Alabama,.
LAZARIDIS, G., 2005. Speleological research in the
Loutra Arideas area (Macedonia, Greece).- In: Neue
Forschungen zum Höhlenbären in Europa.- Naturhis-
torische Gesellscha Nürnber e. V., 45: 57-64, Nürn-
LUNDBERG, J., 2005. Karren.- In: D.C. CULVER & W.
B. WHITE eds, “Encyclopedia of caves”, Elsevier Inc.:
MERCIER, J., 1968. Étude géologique des zones internes
des Hellénides en Macédoine centrale (Gréce).- An-
nales Géologiques des Pays Helléniques, 20: 1-792,
MOUNTRAKIS, D., 1976. Contribution to the knowledge
of the geology of the north boundary of the axios and
Pelagonian zones in the K. Loutraki-Orma area (Al-
mopia).- Ph.D esis, Aristotle University, 164 pp.,
essaloniki (in Greek with English summary).
PALMER, A. N., 2000: Hydrogeologic control of cave pat-
terns.- In: KLIMCHOUK, B. A., FORD, C. D., PALMER,
N. A. & DEYBRODT, W
., eds. “Speleogenesis. Evolution
of karst aquifers”. National Speleological Society: 77-
90, Huntsville, Alabama, U.S.A.
40 Sci. Annals, School of Geology, AUTH, special vol. 98, 2006
PALMER, A. N., 2005: Passage growth and development.-
In: D.C. CULVER & W.B. WHITE eds, “Encyclopedia of
caves”, Elsevier Inc.: 440-444.
PAPPA, S., TSOUKALA, E., LAZARIDIS, G. & RABE-
DER, G., 2005. Milk teeth of Quaternary carnivores
from Northern Greek Caves.- Naturhistorische Gesell-
scha Nürnberg, 45: 169-182, Nürnberg.
PATRAS, D., 1990. Hydrogeological and hydrochemi-
cal research of thermometallic springs in the area of
Loutraki, Aridea (Loutra Pozar). Proc. 2nd Symposium
of mineral waters: 167-185, essaloniki, (in Greek).
PSILOVIKOS, Α. & ΚΑΝETSI, Ε., 1989. Distribution
and paleogeographic signicance of the planation
surfaces on the mountain blocks of the Pelagonian
massif.- Bulletin of the Geological Society of Greece,
RABEDER, G., HOFREITER, M., NAGEL, D. & WITH-
ALM, G., 2004. New taxa of Alpine Cave Bears (ursi-
dae, Camivora).- Cahiers Scientiques, 2: 49-67, Dept.
Du Rhône, Museum Lyon.
TSIRAMBIDES, A., 1998. Study of oor sediments from
the Agiasma Cave of Loutraki, Pella (Macedonia,
Greece).- Bulletin of the Geological Society of Greece,
34: 339-349, (in Greek).
TSOUKALA, E., 1994. Bärenreste aus Loutraki (Mazed.,
Griechen.).- Ursus spelaeus: 2nd Höhlenbären Sympo-
sium (Corvara, 15-18/9/94), Italy.
TSOUKALA, E. & RABEDER, G., 2005. Cave bears and
Late Pleistocene associated faunal remains from Lou-
tra Arideas (Pella, Macedonia, Greece). 15 years of
research.- Naturhistorische Gesellscha Nürnberg, 45:
TSOUKALA E., RABEDER, G. & VERGINIS, S., 1998.
“Ursus spelaeus and associated faunal remains from
Loutraki (Pella, Macedonia, Greece) - Excavations of
1996. Geological and geomorphological approach”.-
4th International Höhlenbären Symposium, 17-
19/9/98, Velenje, Slovenia.
TSOUKALA E., RABEDER, G. & VERGINIS, S., 2001.
Ursus spelaeus and Late Pleistocene associated faunal
remains from Loutraki (Pella, Macedonia, Greece).
Excavations of 1999.- Cadernos Lab. Xeolóx. de Laxe,
26: 441-446, Coruña.
VOUGIOUKALAKIS, G., 2002. Petrological, geochemi-
cal, volcanological study of the Almopias Pliocene
volcanic formations and their correlation with the geo-
thermal manifestations in the area.- Ph.D esis, Ar-
istotle University of essaloniki, 303 pp., (in Greek
with English summary).
WHITE, B. W. & DEIKE III, H. G., 1989. Hydraulic ge-
ometry of cave passages.- In: WHITE, W. & WHITE,
E. “Karst Hydrology”. Concepts from the Mammoth
Cave Area, Van Nostrand Reinhold, 223-258, New
WHITE, L. E. & WHITE, W. B., 2000. Breakdown mor-
phology.- In: KLIMCHOUK, B. A., FORD, C. D., PALM
ER, N. A. & DEYBRODT, W
., eds. “Speleogenesis. Evo-
lution of karst aquifers”. National Speleological Soci-
ety: 427-429, Huntsville, Alabama.