Gams, Ivan

Revistes Catalanes amb Accés Obert

ENDINS, n.' 13.1987. Ciutat de Mallorca. 
ADAPTATION OF THE KARST LAND FOR 
THE AGRARIAN USE IN THE MEDITERRANEAN. 
PROBLEMS OF RESEARCH 
AND OF CONSERVATION (A SURVEY) 
by lvan GAMS * 
En aquest article es revisen els següents rnetodes de recerca: 
1. Analisi de la part superior dels aflorarnents rocosos. En esser tallats a nivell del sol, la terra 
s'ernprava corn a prat. Quan els tallaven rnés arnunt, la terra s'ernprava corn a terreny de pastura o 
corn a prat. En el darrer cas, empero, si la superficie rocosa és Ilisa, el nivell del sol ha estat rebai- 
xat per I'erosió; aquest tipus de superficie nornés es pot formar en contacte arnb el sol. La superfi- 
cie d'una calcaria compacta, exposada a la corrosió causada per les precipitacions i per la meteorit- 
zació rnecanica per darnunt del sol, és cantelluda, clivellada i aspre. 
2. Analisi de les pedres acurnulades per I'horne a parets, rnarges, a la vora inferior de les ter- 
rasses a carnps rostos, o enterrades sota el sol en aquestes terrasses o sota els prats. La mesura de 
llur volurn i pes, efectuada en algunes illes iugoslaves, ha rnostrat que centenars de quilograrns de 
pedaes, en casos excepcionals rnés d'un tona, han estat excavats i trencats per cada rnetre quadrat 
de terra (<netejada>>. 
3. Les formes corn cocons (Kameniea), xaragalls de dissolució (Rundkarrenl, tubs de dissolu- 
ció, solcs de dissolució (Korrosionskehle), i especialrnent els forats de parets Ilises (Kavernosen Ka- 
rren), si són trobats a la superficie indiquen una erosió soterrada. 
4. Els fragrnents de pedra arnb caires vius deixats en el sol després de metejar)) la superficie 
rocosa en alguns carnps representa mes del 10 % del pes del sol. Aixo indica I'extensió de la mete- 
jada)), fins i tot quan les pedres rnajors s'han retirat de la superficie. 
Els ocasionals analisis professionals realitzats a algunes zones carstiques de la Mediterrania. 
han rnostrat que les zones habilitades per ús agricola en epoques antigues eren rnés grans del que 
sabiern per la bibliografia. L'epoca de la netejada no és segura i abarca des de I'epoca fenicia 
(Malta) als ternps rnés recents. 
A rnolts de paisos les rnodernes tecniques agricoles destrueixen les antigues formes de prepa- 
ració de la terra per al conreu arnb aixada i cavec. L'article insisteix en la necessitat de I'estudi dels 
valors ecologics i historics d'aquests anticc testirnonis de I'esforq dels nostres avantpassats pel pro- 
veirnent de rnenjar per llurs vides, i de la conservació d'aquesta herencia natural i cultural. 
Abstract 
The following rnethods of research are reviewed: 
1. Analyses of the outcropping tops of stones. When cut off at the leve1 of the soil, the land 
was used as rneadows. When the tops are cut off in higher position, the land was used as a pasture 
ground or as a rneadow. In the latter case, however, the soil level has been lowered by erosion if 
the stone surface is srnooth. This can develope only in contact with the soil. The surface of solid 
lirnestone, exposed to corrosion caused by the precipitations and by the rnechanical weathering 
above the soil, is sharply fissured and rough. 
2. Analyses of the stones accurnulated by rnan into walls, side walls at the lower edge of the 
slope field terraces, or buried under the soil in such terraces or under the rneadow. Measurernents 
of their volurne and weight, rnade on sorne Yugoslav islands, have shown that several hundred of 
kilograrns, in exceptional case even more than one ton of stones have been dug out and cut off for 
one rn2 of the (<cleared» land. 
3. Subsoil forrns, such as kamenitza, solution runnel (Rundkarren), solution pipe, solution not- 
che (Korrosionskehle), and especially the rocky holes with srnooth walls (Kavernosen Karren) are, 
when on surface, an indicator of the soil erosion too. 
Prof., Departrnent of Geography, Universiiy of Ljubljana, 
ASkerEeva 12, Yu~goslavia. 
4. The stone fragments with sharp edges left in the soil after the .clearing)) of the stony sur- 
face represent in come field more than 10 % of the soil weight. They indicate the extent of the 
((clearing)) even when the bigger stones are removed from the surface. 
The occassional professional analyses, rnade so fare in sorne Mediterranean karst areas. have 
shown rnuch larger adapted areas for agrarian use in ancient times than this is known in the litera- 
ture. The time of clearing is uncertain and reaches from the Phoenician (Malta) to the recent time. 
In rnany countries the modern agricultura1 techniques, destroy the old forrns of land adaptation 
for the cultivation by hoe and spade. The article stresses the need for the study of the ewlogical 
and historical value of these old evidences of the ancient endevour of our ancestors to provide food 
for their life and for the conse~ation of this natural and cultural heritage. 
Forrns of adaptation and research problerns 
described here are not lirnited to the Mediterra- 
nean karst countries only. The results reported 
here are limited to this area because the author is 
more acquainted with it. 
First a brief review of the research methods. 
1. Cutting off the tops of the stones sticking 
out frorn the land surface. 
Surface of the stone cut off is more rough than 
the natural one and this difference ir: noticeable 
even after rnany hundred years. In the northwes- 
tern part of the Dinaric Karst in Yugoslavia and on 
the Adriatic islands, where a larger part of the re- 
sults reported here is derived frorn, the stones cut 
off appear mostly on the pastures. This kind of cut- 
ting presurnably occurred in the transition time 
frorn goat and sheep grazing to cattle grazing. The 
stories cut off appear also in the forests that have 
occupied the abandoned pastures. 
The stone tops cut off are usually higher than 
the soil surface around thern. But originally they 
have been mostly cut off on the level ofthe ground 
nearby. The present difference in the height can be 
considered as an effect of later soil erosion. But 
this rnethod is useful first of al1 when the stones 
cut off appear in a larger area. 
2. Smooth stone surface formed in contact 
with soil and rough one formed in the open air. 
The surface of lirnestone, formed by corrosion 
of the precipitated water and (or) by the mechani- 
cal weathering, is sharp and rough. On both sides 
of the top ridge of some stones Reggenkarren oc- 
cur. Contraty to that the surface of the compact li- 
mestone below the soil cover is smooth. It is 
smooth even in case the pebbles are thin and na- 
rrow. This difference has becorne more obvious, 
especially when the soil around the same stone 
sticking out from the surface has been recently re- 
moved in the lower level. The fresh surface that 
has recently been unearthed is lighter because the 
old one is darker due to the lichen and microorga- 
nisrns. The calcite inlayers are more resistant to 
the corrosion and less to mechanical weathering. 
Therefore under the soil the salients, sticking out 
from the stone surface, are forrned, and in the 
open air the fissures appear in thern. 
There are sorne exceptions in the mentioned 
rule. The surface of the homogeneous limestone 
becornes smooth also under the snow cover if it 
lasts until sumrner (in the alpine belt). In the dense 
deciduous forest the dead leaves and from them 
derived humus cover the larger massive stones 
Photo 1. 
The big Karren prove with their srnooth stone surface 
their subsoil forrnation. The top Regenkarren (solution 
flutes) generated later after the soil was washed away 
due to the agrarian land use (Trieste Karst near to the 
village BriSEiki). 
Photo by l. Gams. 
sticking out from the ground and form the smooth 
stone top surface high above the ground. 
3. Smoothness of the surface of the stone 
has been diminishing in hundreds of years, but the 
proper origin of the initial surface still can be re- 
cognized after a long time. It is often accompanied 
by special stony forms as solution pans from 
which on the surface kamenitzas can be develo- 
ped, as well as covered solution runnels (Rundka- 
rren), solution pipes, solution notches (Korrosions- 
kehlen), covered bogaz, filled funnel-like doline, fi- 
lled pothole (Garns 1971, 1976, Jennings 1985). The 
most important of them is the hole (Kavernosen 
Karren) with smooth walls which can penetrate the 
whole stone mass. 
When estimating the soil erosion rate by 
means of the two mentioned methods one has to 
take into account that the sunshine after the defo- 
restation reaches the ground and accelerates the 
photochemical weathering of the top humus soil 
horizon. This and leaching (eluviation) downward 
after the decay of the roots cause the lowering of 
the soil level, too. 
4. Analyses of the anthropogenic stone accu- 
mulations on the karst surface. 
The stone accumulations typical of the proper 
Mediterranean karst are a by-product of the clea- 
ring of the land for different, mostly for agrarian 
land use. The karst is characterized by the thin inte- 
rrupted soil cover with stones sticking out from the 
surface and by deep soil pockets in the fissures. Ir1 
the natural circumstances such a karst surface is 
suitable only for pastures of sheeps and goats. Cut- 
ting off the stones on the surface makes possible 
to cut down grass with scythe. For tillage it was 
necessary the stones to be removed 15-25 cm be- 
low the arable land surface. 
Forms of the accumulated stones are different 
and typical of regions. Stones can form irregular 
heaps or elongated rows. Systernatically so called 
dry walls or karst walls are built. If the pebbles are 
compounded of one serie, the width of wall is the 
same as the length of pebble. Larger are the walls 
with two series of pebbles. Some of them have the 
inner part between two series filled up by minor 
particles. The accumulations are seldom in form of 
quadrangular tower of pyramidal elevations. ln the 
past centuries the stone accumulation has been in 
some places removed or concentrated in big for- 
mations to get more cultivated land. The stones 
cut off have also been used for buildings, roads, 
lime-kiln, they have also been thrown in the potho- 
les, chasms etc. A part of them had been buried 
under the soil what was proved by bore-holes and 
excavations (Gams 1973, 1974, 1977). The buried 
pebbles have been found: a) In the lower belt of 
the so called cultural terraces. When constructing 
them on the inclined surface the rubble has been 
Photo 2. Side-walls and cultural terraces in the Adriatic island 
LoSinj, near to the town Mali Loginj where in sorne 
plots more than 1.000 kg/rn2 of cut off and accurnula- 
ted stones have been found. 
Photo by l. Gams. 
put on the rocky base along the lower edge of the 
terrace and with the rest of pebbles the vertical 
side-walls has been built. The new arable land in 
the terraces has essentially less inclined surface. 
b) At the clearing of the karst surface the rocky 
trenches with thick soil have been unearthed. After 
the pebbles had been deposited there the rocky 
surface was covered evenly with soil. c) The stones 
cut off on the doline slopes have been thrown in 
the trenches excavated in the bottom. Then al1 the 
available soil stripped off from the slopes was 
spread in the bottom to get a larger field (see 
sketch). d) The fragments of broken stones derived 
from clearing were left in the soil. Their weight ta- 
kes 10 or more percent of the soil weight. These 
fragments prove the clearing in case al1 accumula- 
ted stones were removed from the surface. 
5. lnstead of cutting the stone there it was 
possible to make the soil thick enough with trans- 
portation it from near places. Near to these plots 
the unearthed stones are today usually the highest. 
Deep trenches and dolines have also provided the 
soil for transportation. It is proved by their unnatu- 
ral forms. The soil was seldom stripped off from 
the whole nearby slopes and thus made infertile 
(example NW of St. Julians on Malta). The differen- 
ce in soil structure in the doline bottom and around 
it is also an indicator for transportation (Lovrenriak, 
1977). 
Some forms of the alteration of karst surface due to cultivation: Forms of accurnulated grave1 (pebbles) collected at the process of 
a - natural surface, b - alterated and cultivated surface. cultivation: 
1 - Field terraces on slope in semicovered karst. 2 - Alteration 4 - Heap of stones. 5 - Heap of stones arranged in a series. 6 - 
of the more funnel-shaped doline into the more bowl-like doline Wall built in one series. 7 - Wall built in two series. 8 - Wall built in 
to get a larger acre on its bonom. 3 - Alteration of the semicove- two series with inner filling. 9 - Quadrangular tower (from: Gams, 
red karst into the covered karst in a meadow. 1974). 
Photo 3. 
Form of accumulated stones used for temporaty dwe- 
lling of peasant on the field near Stari grad where come 
side-walls still indicate the Greek field parcelling from 
the 2th centuty b.Ch. 
Photo by l. Gams. 
6. Historical development of the adaptation 
of karst surface. 
The knowledge of it in single countries and in 
the whole Mediterranean world is deficient, the 
historical sources scarce and human rnernory lost. 
For example: The Polyglot guide-book entitled 
«Malta» reports that the Phoeniciens (there from 
14th-18th century b.ch.) ((brought the fertile soil to 
Malta, covered the nacked rocky surface with it and 
so acres, vineyards and cotton plants were introdu- 
ced)) (p. 8). The preliminary research showed that 
in this limestone countty the soil had in reality 
been derived from the local clearing of stony sur- 
face. It was easy to be cleared due to the light and 
soft limestone. lmportation of the soil could contri- 
bute only a negligible share to it. The guide-book 
has probably right in cense that the Phoenicians 
brought the culture of adaptation of karst surface 
already. East of the small town Stari grad on the 
Yugoslav island Hvar the Greek parcelling of the 
field (4th-2nd cent, b.Ch.) still can be seen in the 
form of walls. The regular Greek parcelling in «Sta- 
dies)) and ((plethrones)) was possible only in a 
plain area without blocks sticking out from the 
ground. Today this field is dotted with stones. 
Since the Phoenician and.Greek epoches the adap- 
tation has been continued till the present time. The 
new agricultural techniques brought also new 
adaptations and consequently the changes in culti- 
vation of land using hoe, spade, later plough, and 
recently tractor. A deeper clearing of stones was 
necessary when the olive-trees replaced the fig- 
trees and later vineyards. Therefore the stones had 
to be cut off down to the depths of 80-100 cm. 
Every country has his own historical development. 
The walls in Pennins (England) were mainly built in 
the transition from feudal to private land tenure - it 
was in the 17th and 18th century (Raistrick, 1969). 
The amount of work for adaptation of the karst 
land for agricultural use can be elucidated by mea- 
suring the weight of excavated stones. The rneasu- 
red volume of al1 the stones accumulated on the 
surface can be diverted (specific weight 2,7-2,8, va- 
lue diminished by factor about 0,2 due to empty 
voids between the stones) into weight. This kind of 
measurements showed mainly less than one hun- 
dred kg/m2 of land from where the stones had 
been taken away. On the Yugoslav islands in the 
Adriatic sea this value rises to many hundreds 
kg/m2 and in some exceptional cases (LoSinj, - 
Gams 1974, 216) more than 1000 kg/m2. Invisible 
stones under the soil and those in the soil were 
neglected. After deforestation the decay of tree 
roots has lowered the soil level for some centime- 
tres. In case of one thousand kilos of excavated 
stones the soil level has been equivalently to their 
volume lowered for 21,6 cm. Both factors have 
contributed to the general soil (cerosion)). 
The study of alteration of karst surface is im- 
portant for many reasons. It is useful for pedology 
since the natural soil horizons have been comple- 
tely destroyed and mixed. It can be of great help to 
the archeological excavations in establishing the 
natural surface. The alterations have entirely chan- 
ged the ecological conditions. The resilient rubble 
in the soil has a better heat conductivity than the 
soil particles. The altered soil is therefore warmer 
in summer. If the pebbles are lying below the soil it 
is more arid and colder rain provokes a smaller re- 
duction of the soil temperature. The inwalled plots 
have a reduced wind speed and therefore a higher 
daily maximal air temperatures. The walls hinder 
the gliding of near-to-surface cool air layer on the 
slope. The karst depressions with the walls are the- 
refore warmer in winter. The walls hinder the soil 
erosion and also spreading of forest and grass fi- 
res. But in the same time the soil of cultivated land 
without any grass on the surface is more liable to 
soil wash and vertical leaching. Peasants often say 
the stones «grow)). 
Beside the ecological advances of cultivated 
land also some difficulties are to be found there. 
The walls hinder the traffic and cultivation of land 
by means of al1 kinds of machines. They also hin- 
der the creation of larger fields to be possessed by 
one farmer only. For this and the other reasons the 
agrarian use of the altered karst land is on the de- 
crease in modern time. The intensive use is more 
and more limited to the vicinity of the settlements 
and to less inwalled and less inclined plots, that 
are mostly on the bottom of the depressions and in 
the valleys. But the ancient agricultural land is 
being rapidly destroyed there by the traffic, roads, 
railways, and by the other non-agrarian activities. 
The inwalled plots seems to be incompatible with 
the modern agrarian techniques. But with the de- 
cay of nearly one thousand years old cultural karst 
land the cultural heritage would be most affected. 
Thus an evidence of the year-long endeavours of 
our ancestors for their life and food should be lost. 
At least some samples should be conserved for our 
future generations. From this point of view we 
have to register the dying forms of cultivation, the 
remnants of human knowledge, and the effects of 
alterations before the agricultural land of new set- 
tlements is utilized and new techniques with trac- 
tor and harvester used. 
References 
GAMS. 1. (1971): Podtalne kraSke oblike (Subsoil karst forms). Geo- 
grafski vestnik XLIII, Ljubljana. 
GAMS. 1. (1973): A new method of determining of the karst soil 
erosion. Proc. 6th Int. Congress of Speleology, Olornouc 1973, 
CSSR Il.t., Praha. 
GAMS. 1. (1974): Kras. Ljubljana. 
GAMS, 1. (1976): Forrns of subsoil karst. Proc. 6th Int. Congress of 
Speleology, Olomouc 1973, CSSR, Il.t., Praha. 
GAMS. 1. (1977): Einige Arten der Umwandlung des halbbedeckten 
Karstes durch die landwirtschaftliche Bebauung. Proc. 6th Int. 
Congress of Speleology, Olornouc 1973, CSSR, Praha. 
JENNINGS, J.N. (1985): Karst Geomorphology. Oxford. 
LOVRENCAK, F. (1977): Odeja prsti v vrtawh Slovenije (Boden- 
decke in den Dolinen Sloweniens). Zbornik X. jub. kongresa 
geografa Jugoslavije u Srbiji 1976. Beograd. 
MALTA: Polyglott-Reiseführer. München. 
RAISTRICK, A. (1969): Pennine Walls. Clapharn. 


Adaptation of the karst land for the agrarian use in the Mediterranean. Problems of research and of conservation (a survey)

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