y

Suppl. Geogr. Fis. Dinam. QUal.

III, T. 2 (I 997), 205-213, 11 figg., 1 lob.

FOURTH INTERNATIONAL CONFEREN€EON GEOMORPHOLOGY - ltaly 1997 Guide for the excurSlon

GEOMORPHIC EVOLUTION OF KARST

AND FLUVIAL BASINS IN THE SURROUNDINGS OF BOLOGNA

E.

FARABEGOLI, &

P.

FORTI

C)

INTRODUCTION The Northern Apennines is a type A collisional moun­ tain belt (fig. 1). The northeastern sector of the structure is covered by a thick sequence of Pleistocene alluvial sedi­ ments of the Po Plain (PIERI & GROPPI 1981). The main information about the geology of the Bolo­ gna Apennines derived from about 40 yrs of oil well dril­ ling and seismic exploration (BONGIORNI 1963, PIERI & GROPPI, 1981) as well as by detailed geologica l mapping (FARABEGOLI 1990; PINI 1993). Further information carne from geomorphological mapping and detailed stratigraphic researches on a large number of paleolithic sites (LENZI & NENZIONI,1997). The Bologna area underwent a very strong tectonic reactivation starUng from the Upper Miocene. The uplift of the northeastern flank of the frontal anticline of the Apen­ nines, caused the progressive exposure and erosion of the Miocene-Quaternary sediments. The southwestern flank of the anticline was covered with Mio-Pliocene chaotic ter­ rains, of sedimentary and tectonic origin, intensively folded and faulted during the Plio-Pleistocene (fig. 2). The asses­ sed rate of the tectonic uplift was about 0.5 m/kyr in the la­ st million years, whereas the average subsidence rate of the basin was of about 1m/kyr (the maximum reached 3 m/kyr) The Apennines watershed is about 1500 m high. Weather is temperate and temperate-humid: rainfall in­ creases from 650 mm/yr along the Adriatic coast to about 2000 mm/yr along the watershed. The medium rainfall at the boundary Apennines-Po Plain reaches the 900 mm/yr, but in a few areas (Le. the Vena del Gesso) it lowers to less than 700 mm/yr. Rainy periods are late spring and, expe­ cially, autumn.

DJ

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.

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:'Otlll

[ili

APENNINES A.P.

PlIJL'1

PIi

la - Geological map of rhe Norrhern Apennines and Po Plain (Emi­ lia-Romagna). Legend: 1. alluvial fan and alluvial plain (Upper Pleisroce­ ne-Olocene); 2. oldesr alluvial fans , major rriangular e1emenrs and rerra­ ced valley sedimenrs; 3. Imola Yello Sands (Lower Pleisrocene); 4. Mari­ ne c1ays and sands (Early Pleisrocene·Pliocene; 5. Pre·Pliocene unirs; 6. rhrusr faulr; 7. faulr; 8. Pliocene borrom surface deprh (km) conrour line; 9. oil well; lO. Cenronara carchmenr.

FIG .

lb . Geologica! cross secrion sourh of Bologna. Legend: A.P .. Padan AIIuvium; S.G.1.. Imola Yellow sands; S.A .. Asti Sands; Q. Early Pleisro· cene marine sedimenrs; Plms. MiddJe·Upper Pliocene; PIi. Lower Plioce­ ne; L. Pliocene olisrosrromes; Ms. Upper Miocene; Mm. Middle Miocene (modified aher Pieri & Groppi 1980).

FIG.

(l) Dipartimento di Scienze della Terra e Geologico-Ambientali Università

di Bologna, Italy.

Ricerca eseguita con Fondi Murst 40 % e 60% e Cnr.

205

FIG. 2 . The Emilia.Romagna geological structure and lanscape. Legend: 1. metamorphic basemenr, 2. Triossic·Pliocene «autoctonous» Romagna sequence, 3. Chaoric Complex, 4. Mesozoic·Lower Miocen e «Tuscan sedimentary sequence», 5. Pleistocene sediments, 6. thrust faulr.

The main fluvial valleys, spaced 5-10 km, are superim­ posed on important transversal faults oriented N35 °E or N-S. The prevalent shape of the valleys is e1ongated; the length range from 25 to 60 km, the width from 4 to 10 km and the area from about 150 to about 1000 km 2• The tecto­ nic structure is the most important factor causing the gene· ral shape and location of the valleys; lithology, joints, weather, so il use, etc., are responsible for low scale internai geomorphic characters: hydrographic pattem, landscape, etc. The valleys contain hierarchically ordered concave areas (basins, sub-basin, complex catchment, catchment, celi) separated locally by residual sub-triangular areas (Triangular e1ements, e of fig . 2) sloping 10-20°. Major Triangular Elements (E of fig. 2), usually 5-10 km wide and sloping 4_9° Northeast, divide the main valleys along the Apennines margino Two major erosion processes are active: a) channeled erosion; b) mass wasting Oandslides). The transition from the uplifting to the subsiding sec· tor of the Apennines occurs within large band of a few ki­ lometers, which encloses the main alluvial fans as well as the interfan areas, located at the foothills of the major triangular elements. The strarigraphic research carried out on the margin al· lowed to date the assessment of the oldest alluvial deposits of the fans about 800,000 B.P.years and to confirm that the uplift and subsidence rates didn't keep constant (FARABE­ GOL! & ONOREVOLI, 1989, 1992, 1996, 1997). During this lenghty period of time, 7 main glacial phases (1.s.) and 7 long interglacial periods succeeded, featured repeated switches from arid temperate-cold to humid temperate and arid warm climate. Most of the alluvial fans' sediments de· posited by progradation-aggradation during the first late/ post-glacial humid phases, when the lack of plant co­ ver didn't grant a sufficient yield against erosion. The warm arid periods feature characteristic brown-reddish soils, whereas during the arid colds periods some thin loess co­ vers developed locally. The constant relief rejuvenation allowed the terraced erosion within the valley and on the apices of the fans, the latter developing a «telescopic» prograding structure. Ac­ tually the apenninic-padan alluvial fans are complex landforms, whose total area represents the result of the

206

events from 200 to 40 kyrs. The Holocene deposits are shifted towards the coastal areas. The uplift and tilting of the major triangular elements recently increased the ero­ sion rate and the «cannibalistic» enlargement of the minor catchments. The Rio Centonara - Rio Ciagnano catchment, subject of this field trip, is located within a major triangular ele­ ment, whose elevation ranges between 50 and 350 m above the s.I., about 10 km south of Bologna. The Gessoso-solfifera Formarion, deposited during the Messinian salinity crisis, emerges as a !inear ridge (fR 276ER_, lER

_

i i .

HG

i

F

~ ~""""'ìi

2*

Ou.~~ ~&& ~ ,~ ==== --~ ____ -·115

'fR

mO .

500 ,

i

E

i

D

C

i e

s

N

FIG. 5 - The Spipola-Acquafredda Karst System.

207

From tbe point of view of the geomorphology in the subterranean cavities the following types can be distingui­ shed (FORTI & SAURO, 1997): m) tunnels resulting from «horizontal erosion», and/or from the fusion of several sub-horizontal tubes; n) pseudo-galleries, resulting from the fusion of several cavities, most commonly formed by vertical percolacion along fissures; o) cylindrical and «ogival» (arch-shaped) pits and ca­ vities; p) waterfall pits, locally with potholes, q) collapse chambers; r) cavities formed due to slope tectonics. A very common feature is the «pseudo-phreatic tube», which is similar in appearance to a normal phreatic con­ duit but develops starting from tunnels that are almost completely filled by sediments, and so has its roof and wal­ ls in gypsum and its floor in sedimento If the sediments are eroded the result is typical galleries with ceiling half tubes. Within the main drainage tubes of tbe active caves the presence of suspended material in the water has been de­ monstrated as being by far the main influence upon the en­ largement of some active cave passages. On average me­ chanical erosion represents over 60% of tbe overall mass wasting of the cave walls. Condensation dissolution is the second most important effect (about 30%), and normal dissolution is by far the least active process in this situa­ tion, while the incongruent dissolution is uneffective. C!-IEMICAL DEPOSITS Chemical deposits are scarce in the caves of this area. When considering the secondary minerals that can be found inside the gypsum caves of Bologna, it must be re­ membered tbat up until the early nineteen-seventies only two minerals had been identified. Actually occurrences of about lO minerals have already been described (FORTI, 1997). In the gypsum caves of Bologna speleothems exist essentially as calcite and gypsum deposits; these two cate­ gories are considered separately. a) Calcite speleothems Calcite speleothems are reasonably widespread: stalac­ tites, flowstone, splash concretions and cave pearls are the most common forms, and they show no morphological pe­ culiarities to distinguish tbem from sirnilar deposits in li­ mestone caves. Normally tbe formation of calcite spe­ leothems in gypsum caves is no more than a product of the incongruent dissolution of gypsum by water witb a high initial carbon dioxide content. A distinctive characteristic of calcite speleothems formed by this mechanism is that they are almost inevitably found a few metres, or a litrle more, from the point where the water inlet enters the void in the gypsum rock. Incongruent dissolution explains not only the origin of normal speleothems in many gypsum caves, but also the existence of unique forms (observed only in this environ­ ment) comprising crusts detached almost completely from highly corroded gypsum walls. The same mechanism is al208

so responsible for the development of large (14 m high, 2 m wide and typically less than 20 cm thick) «calcite bla­ des» with mud nuclei (FORTI & RABBI, 1981). While considering how rapidly calcite speleothems de­ velop in a gypsum environment, it was observed that, con­ tniry to what might be supposed, the development velocity is commonly higher than tbat of sirnilar forms in limestone caves. Experimental observations have demonstrated a growth rate of almost 1mm/year for some flowstones (DAL MONTE & FORTI, 1995). Faster growth rates of calcite spe­ leothems in gypsum environments relative to tbose in lime­ stone are clear1y associated with the exceptional efficiency of tbe incongruent dissolution processo (FORTI, 1991). Lasrly, it has been noted that there is a difference between what happens in limestone caves and gypsum ca­ ves with regard to the formation of structural bands within calcite speleothems. In gypsum caves, rather than spe­ leothems displaying an annual cyclicity, a much higher fre­ quency of banding is typically present (CAZZOLI & a/ii, 1988). The explanation of this is again related to the incon­ gruent dissolutional mechanism, which is active only in the first few metres of percolation inside the gypsum. Close to tbe surface impulses caused by individuaI rainfall events are stili important, and frequent hiatuses in the water sup­ ply potentially lead to the evolution 'af a new growth layer with each stop and start in the precipitation. b) Gypsum speleothems Despite the aspects discussed above, it is the gypsum speleothems and crystal forms tbat hold the strongest ele­ ments of interest, as well as having a more ubiquitous di­ stribution. Gypsum speleothems present obvious morpho­ logical differences compared to calcite ones, due to their distinct genetic mechanism, which involves supersatura­ tion due to evaporation. Gypsum stalactites are typically more contorted, spotted and multi-branched. In most ca­ ses their growth depends much more, if not exclusively, upon surficial percolation water rather than upon water that feeds tbrough a centraI tube. This commonly results in the centraI tube being absent, or partially (if not comple­ tely) obstructed. The effect of permanent air currents (or at least those tbat are active during the stalactites growth periods) is the exact opposite with respect to calcite and gypsum stalacti­ teso In fact, in the case of the former, as the growth mecha­ nism is controlled by carbon dioxide diffusion, which is not influenced in any way by the air current, there is com­ monly a deviation of the stalactite in the direction of air movement, which is the same direction that the water dro­ plets are deviated before they fali. In the case of gypsum stalactites, the inverse effect dominates, as the speleothems deviate towards the source of the air current, where maxi­ mum evaporation occurs. Gypsum crystals, between severa l microns and more tban a metre in length, are without doubt the most com­ mon secondary deposit found in caves at all latitudes and in all clima tic zones. They are commonly found as free de­ posits, though more typically they form druses anchored to tbe cave walls.

together with others ali related to a cold climate allowed to The largest crystals (some more than a metre long) typi­ cally form inside clayey sandy interbeds in the caves of date this fauna to a cold interval of the Wurm glaciation. temperate areas, where their development is driven by the The age of the skeletal remains are in agreement with that slow flow of capillary waters, whose evaporation causes a of the early stages in the development of the karst inside very smalilevel of supersaturation. It is not feasible to de­ _the gypsum. Quarrying activities exposed three small sinkholes in scribe ali the different varieties, types and forms of gypsum the «Cava Yecme» , named A, B, C. Sinkholes A, B preser­ crystals here, as they display enormous variations with re­ spect to shape, dimensions and purity. The genetic mecha­ ved Middle Paleolithic Equus, Bos primigenius, Bison bona­ nisms can also vary significantly, even though at a simple sus, Megaloceras giganteus (LENZI & NENZIONI 1996). level the genesis of these crystals can normally be viewed as The sinkhole of the «Cava Yecme» as been completely the result of simple supersaturation following evaporation. destroyed , while a part of that of «Cava Filo» is stili visible Detailed discussions of these questions can be found in inside that quarry. Most of the materials from those specific papers by CASALI & FORTI (1969), HILL & FORTI sinkholes are presently preserved in the Paleontological (1986) and FORTI (1997). Museum of University of Bologna and in the «Luigi Doni­ Gypsum flowers, which represent the genetic analogues ni Museum» in S. Lazzaro di Savena. of calcite coralloids, are practically ubiquitous, and owe their genesis to evaporation of a thin water film that is drawn slowly up wall discontinuities, drive n by capillarity. THE CENTONARA CATCHMENT Their evolution is relatively rapid and appears identical to South of Bologna, along the padan Apenninic margin, that of the calcite or aragonite coralloids in limestone ca­ the Idice and Sellustra valleys bound a major Triangular ves. Another relatively unusual type of inflorescence, thou­ Element, about 6 km long. The area contain four catch­ gh more common in caves with a humid temperate or tro­ ments (Olmatello, Marzano, Centonara- Ciagnano, and pical climate, takes the form of the gypsum crystals Gorgara), the creeks of which produced small alluvial fans growing over active calcite speleothems. This occurs at the catchment reaches . The Cen'tonara-Ciagnano is a notwithstanding the fact that the gypsum precipitation me­ complex catchment a few sq km wide, featuring a 5th or­ chanism is completely different to that of calcite in a gy­ der channel network and widespread badland-type psum cave. The calcite precipitates due to diffusion of car­ landforms. The erosion supplies the source for a lO sq km bon dioxide into the cave atmosphere, or following incon­ gruent dissolution, whereas the gypsum is deposited as a wide sandy-silty alluvial fan overlying and partially interfin­ result of supersaturation due to evaporation. gering with 3rd order deposits of the main alluvial fans at the catchment reach. HUMAN IMPACT AND PRESERVATION The Centonara creek is the principal rributary of the The human impact upon the gypsum karst of Bologna Centonara-Ciagnano creek. The Centonara catchment, has been generally very strong since early ages due to its 2.43 sq km wide, is the study area of the Department of Agronomy (University of Bologna) for the short-term soil closeness to the town. loss on cultivated plots (ROSSI PISA & alii, 1994), by means Quarrying was the most important form of human im­ of an automatic station for continuous measures of ero­ pact: many large quarries have been opened since Roman times. Mediaeval towers in the town of Bologna were builr sion. Moreover, a mathematical model was elaborated in order to extimate the medium-term erosion at the basin with blocks of macro-crystalline gypsum. During this cen­ scale (ROSSI PISA & alii, 1994).The long-term erosion at tury larger quarries have been opened , leading to the de­ the basin scale has been evaluated considering the geo­ struction of several caves and the burial of some dolines. morphyc parameters, and some relationships between the In recent times the complete stop of the quarrying acti­ parameters (slope angle, land use, lithology, etc.) have vities and the settlement of the Natural Park over the who­ le gypsum area allowed the preservation of this small, but been pointed out (FARABEGOLI & alii, 1994). The sandy-silty alluvial fan deposits post-date 70 kyr b3 extremely interesting gypsum karst zone. terrace and pre-date a 8 kyr old surface containing meso­ lithic manufacts (FARABEGOLI & alii, 1995). Locally, allu­ THE BURIED SINKHOLES AND THEIR FAUNA vial sediments referred to 4rd (Riss II-Wiirm: 110 kyr) and Quarrying activities exposed small buried sinkholes, re­ 5rd (Riss I-Riss II: 200 kyr) order terraces cover the slopes spectively in upper southern margin of the Spipola doline of the catchment, whereas older terraces (6rd and 7rd or­ and on top of M. Croara. der) lies on the watershed and cover the major triangular The first one was exposed and partially destroyed in elements (fig. 6) . 1966 inside the «Cava Filo» quarry (PASINI, 1970) . The Italian Institute of Speleology was allowed to study the in­ filling of this sinkhole wich contains several well preserved skeletal remains of mammals, the most imponant and rare of which are Megacerus Giganteus, Bison (superbison), Mar­ morta marmorta primigenia. The occurence Megacerus Gi­ ganteus (known in Europe only in the Upper Pleistocene)

GEOLOGY The compIe x geological structure of the Centonara cat­ chment is shown in fig. 6. Below the alluvial cover of the triangular elements crops out a yellowish 50 m thick sand­ stone unit (Sabbie Gialle di Imola Formation, S.G.1. in fig.

209

N

~ ~JI~~~:::,7~~)~~~

~ hy2); it consists of 5 hydrographic cells, separated by

triangular elements (fig. 7). Two elongated triangular ele­ ments consti tute the northem part of the catchment, where low relief energy (less than 100 m) and the carbonatic ce­ ment of the S.G.l. formation prevented the evolution of tri­ butary channels, thus preserving the valley terraced deposits. The high relief and the intensily fractured day substra­ tum favoured the intense channel erosion and mass wa­ sting of the southem part of the catchment, producing ty­ pical badland landforms. The channel network, of dendritic type, feature a 5th order (sensu Strahler 1958) channel network: n. 165-lth, 32-2th, 7 -3th, 2-4th. The values of the hydromorphic para­ meters (Rb, Ga, etc., see tab. 1) are in agreement with the rapid evolution of the catchment.

TABLE 1 . Main geomorphic paramelers and Tu of Ihe Cemonara calchmem

celi CI C2 C2 C4 C5 Cemonara carch

order 3° 4° 2° 4° 3° 5°

area

km

,

0,30 0,15 0,51 0,27 0,04 2,73

s[ream

Number of channels

length km

1°

2°

3°

1,81 2,80 2 ,42 5,73 0,80 18,67

Il 31 8 88 5 165

3 6 1 17 2 32

1 2

4°

Rb = bifurcation ratio (arithmetic mean) Rbd = direct bifurcation ratio (arithmetic mean) Rb' = bifurcation rario (weighted mean) Rbd* = direct bifurcation rario (weighled mean)

210

2

Rb

Rbd

Rb'

Rbd*

R

R*

CA

ga

3,33 3,29 8,00 4,61 2,25 3,81

3,17 2,72 8,00 4,30 2,00 3,27

3,52 4,67 8,00 5, 19 2,36 4,98

3,26 3,75 8,00 4,46 2,00 4,01

0,16 0,67 0,00 0,31 0,25 0,54

0,26 0,92 0,00 0,73 0,36 0,97

1 18

3,4 117,6

18 1 82

66,7 28,6 30,0

5°

R R* CA ga

= bifurcation index (arithmetic mean)

= bifurcation index (weighted mean)

= hierarchinal anomaly number

= hierarchinal anomaly index

sedimenr yield (Tu) ton / km' x yr 1849 47004 916 62860 76821 2906

Slape pracesses landfarms 16 ­ The cyclical deepening of the channel imo the day be­ drock is of primary importance for me cominuous starting of mass wascing. A large number of superficial earth- and .12 ­ complex slides develop during periods in in which the rainfall varies from 150 co 350 mm/3 days. Generally, wet periods repeated cydically each 10-15 yr. ~ 8>­ At present the wasring phenomenon, as typical Apenni­ "c nes «calanchi» landform, cover about the 30 % of the cat­ :J

o­ chmem area (fig. 8). ~ 4-

~

r--

~

r---

~

~

r---

Q)

N

§

D

O

> 10

unstahle area

10-15

15-20

20-30

30-35

35·50

> 50

slape classes (%)

"calanchi"

FIG. 9 - The platykurtic freguency disrributien ef Centenara sIepe classes cemes an ene side from the cheise ef a class (>50 %) which is wider than the ethers, and en the other side from the wide diffusien ef the Imela Yellew Sands that raised the siepe class < 10 %.

lan"slid"

,

The frequency distribution of 7 dasses of slope angle (10,20, .. .,50% and >50%), obtained from a copographic map with 10m spaced contour elevation !ines, is platykur­ tic (fig. 9). This resulr derives from the high frequences of surfaces less steep than 10 % (on sandscone bedrock) and steeper than 50% (in badJand-type areas). The dinomeeric method was applied co a badlaild-type catchment using Il slope dasses and contour elevation lines every 50, 25 and 10 m (fig. 10-11). The diagrams point out (SANMARCHI 1997) that it is possible co obtain a realisti c representation of badland morphology only starting from the lO m spaced contour lines (fig. Il). o

5(K) Ilt

Land Use F IG. 8 . Siepe processes landferms in the Centenara catchment.

Slape angle Hillslope steepness is both me result of long-term (100 kyr) morphogenesis and the major reason for the wasting phenomenon. On the other hand, me slope of calanchi-ty­ pe landforms its not easy neither to measure nor co map­ ping using standard carthographic methods (DEM, TIN or Clinometric) . We tested the reliability of me clinometric method, using an automaric computer procedure specially develo­ ped in the Depanmem (CASADEI 1997) in order co avoid the time loss connected wim manual graphical procedures. Moreover, we tried co verify the variability of slope diseri­ burion using a different number of slope angle classes and contour elevation lines spaced respeccively 50,25 and lO m.

Most of the area is devoted to agriculrural land use (50%); marginaI woods cover the 20% of me catchment, shrubbery (11 % ) and grasslands (9 %) prevail in the po­ tenrial unstable areas, whereas bedrock (10 %) characteri­ zes badland-type areas.

Data analysis The search of the common areas from each pairs of polygons belonging co different thematic maps point out rwo direct relationships: Erosion processes vs. lithology-Most of the erosion processes (channeled and landslides) tend co concentrate on the day fracrured bedrock. Landslides vs. Slope angle-Slope angle exceeding 16° (30 %) characterizes shorr-term unstable surfaces. Flows and complex landslides depositional areas are con­ centrated upon surfaces featuring slope angle lower than 20 %. 211

badland celi· 50 m spaced contour elevation Unes

badland celi· 10m sp.ced conlour elevatlon IInes lO..

60%

f-­

'0"

F

"" 40%

Fi

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'2%

F

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20%

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slope c1a sses (%) sub-catchm ent - 50 m spaced conlour elevati on Hnes

,c

1: ~

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FIC;, lO ' Usin!l Il slope c1 asses anu cont our lin es el'e ry 50 (Jefd or 25 (ri ghr l, \l'e obtaincu a non 'rea lis tic slo pe uist ribution or anu, expeci all y, or a bau lanu cel i (Centonara bas in l,

badland celi· 10m spaced contour elevallon IIn.s

=

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1 0~

sub -carc'hlllcnt

c:

=,c;

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slIb ·eatehment - 10m spaeed contollr elevat ion IIne5

C-

.,,,

~

~

,c

' 0%

1 0~

~ 5:

slope classes (%)

,c::,

P

~ '4

~

~

g

,, %

25%

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sub--catchment ·10 m spac.d contour el.valio" lines

....

30%

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C7 f=(

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~ :6000 ton km- yr- ) of rypical badlad cells (CICCACCI, D'ALESSANDRO & alii, 1988) . This resulr is consisrenr wirh rhe short-rerm soilloss (22 ron ha- 1yr- 1) measured in a period of few years in a maize plor 15 % sloping (RoSSI PISA & alii, 1994) as well as rhe 1 1 value of 22 ron ha- yr- obrained using rhe Usle (Universal Soil Loss Equarion). The exrimared (Usle) soilloss of mea­ 1 1 dow plors reduces ro a renrh (1.9 ton ha- yr- ). REFERENCES BONGIORNI D. (1963) - Geologia del settore Bolognese. In: Luccheni L., Alberrelli L. , Mazzei R. , Thieme R., Bongiorni D. & Dondi L. - Con­ tributo alle conoscenze geologiche del Pedeappennino Padano. Boll. Soc. Geol. It., 81, 80-112. CALAFORRA J. M. (1996) - Contribucion al conocimiento de la Karstologia de Yesos. PhD Thesis, University of Granada, 350 pp. CA SA DEr M. (1997) - Analisi quantitativa delle relazionifra i parametri geo­ morfologici e l'evoluzione del dissesto nell'Appennino Settentrionale. Unpublished PhD Thesis, Università di Bologna . CAZZOLI M., FORTI P. & BETIAZZI L. (1988) - L'accrescimento di alabastri calcarei in grotte gessose: nuovi dati dalla grOlla dell'Acquafredda (3/ER/Bo). Sono terra, 80, 16-23. CICCACCI S., mDI P., LUPIA PALMIERl E. & PUGLIESE F. (1981) - Contri­ buto dell'analisi geomorfica quantitativa alla valutazione dell'entità dell'erosione nei bacini/luviali. BolI. Soc. Geo!. Il. , 99,455-516. CICCACCI S., D'ALESSANDRO L., FREDI P. & LUPIA PALMIERl E. (1988) ­ Contributo dell'analisi geomorfica quantitativa allo studio dei processi di denudazione nel bacino idrografico del torrente Paglia (Toscana me­ ridionale-Lazio settentrionale). Supp!. Geogr. Fis. Dinam. Qual., 1, 171 -188. CUCCH I F., FI NOCC HI ARO F. & FORTI P. (1997) - Gypsum degradation in tbe Mediterranean area witb respect to climatic, textural and erosional conditions. In presso DAL MONTE C. & FORTI P. (1995) - L'evoluzione delle concrezioni di car­ bonato di calcio all'interno delle grotte in gesso: dati sperimentali dal Parco dei Gessi Bolognesi. SonOlerra, 102, 32-40.

FARABEGOLI E. (Dir. Rilevamento) (1990) - Carta geologica dett'AppeJllli­ no emiliano-romagnolo alla scala 1:10.000, Sezione 238110 Fontaneli­ ce. Selca, Firenze. FARABEGOLI E. (996) -l siti paleoliticifra Bologna e Imola in relazione al­ l'evoluzione geomorfologica e paleogeografica del territorio. In: Lenzi F. & Nenzioni G. (a cura di) - Lenere di pietra. I depositi pleiswceni­ ci: sedimemi, industrie e faune del margine appenninico-bolognese. 39-64, Ed. Composiwri, Bologna. E. FARABEGOLI, F. FONTANA, A. GUARRESCHI & G. NENZIONI (1994) - Il sito mesolitico dell'l.N.F.S. di Colunga (Ozzano dell'Emilia, Bologna). BolI. Palern. Il., 85, 73-133. FARABEGOLI E. & ONOREVOLI G. (1989) - Introduzione all'analisi dei de­ positi attuvionali quatemari del margine appenninico padano. Il fiume Savio. Giorn. Geol., ser. 3,51 (1) , 119-146. FARA BEGOLI E. & O NOREVOLI G. (1992) - La Sezione di S. Mamante (Faellza) ileI quadro evolutivo neotettonico ed eustatico del Quatemario dett'Appennino Romagnolo. Mem. Descr. Carra Geol. It., 46, Roma. FARABEGOLI E. & ONOREVOLI G. (1996) - Il margine appenninico emilia­ no-romagnolo durante il Quatemanò: stratigrafia ed eventi. In: Lenzi F. & Nenzioni G. (a cura di) - Lenere di pietra. I depositi pleiswceni­ ci: sedimemi, industrie e faune del margine appenninico-bolognese. 19-37 , Ed. Composiwri, Bologna. E. FARABEGOLI, ROSSI PISA P., CosTANnNI B. & GARDI I C. (1994) - Car­ tografia tematica per lo studio dell'eroslòl1e a scala di bacino. Riv. Agronomia, Edagricole, Bologna, 356-366. FORTI P. (1991) - Il Carsismo nei gessi con particolare riguardo a quelli del­ l'Emilia-Romagna. Spel. Em. S. 4, 2, p. 11-36. FORTI P. (J 996) - Erosion rate, crystal size an~ exokarst microforms, Proc. 1m. Symp. on Karren Landforms, Soller (Mallorca), 19-22 Senembre 1995,261-276. FORTI P. (1997) - Speleotbems and cave minerals in gypsum caves. 1m. . Journ. Speleol., 24, in presso FORTI P. & RABBr E. (981) - Tbe role ofC02 in g)'psum speleogenesis: lO contribution. 1m. Journ. Speleol., Il,207-218. FORTI P. & SAURO U. (] 997) - Gypsum karst of Italy. 1m. Journ. Speleol., 24, in presso HILL C. & FORTI P. (1986) - Cave Minerals of tbe World. Nat. Spel. Soc., Humsville, 236 pp. LENZI F. & NENZIONI G. (a cura di) (996) - Lettere di pietra. l depositi pleistocenici: sedimentI; industrie e faune del margine appenninico-bo­ lognese. pp. 19-37, Ed. Com posiwri, Bologna. PASI NI G. (970) . Fauna a mammIferi del Pleistocene superiore in un pa­ leoingblòttitolò carsico presso M. Croara. PIERl & GROPPI O98 l) - Subsurface geological structure of tbe Po Piain, Italy. Pubbl. 414 , 23 pp., Cnr, P.F. Geodinamica. PI NI G.A. (1993) - Geological map of tbe Bologna area footbitts. Cnr, Gra­ fiche Step, Parma. ROSSI PISA P., VICARl A. & CAnZONE P. (}994) - Effetto della copertura vegetale di orzo (Ordeum vulgare L.) sull' erosione e sutta qualità delle acque di ruscellamento. Riv. Agronomia, 28 (4), 384-391, Bologna. SANMARCHI F. (997) - Distribuzione delle dassi di acdività con il metodo dinometrico in relazione alla scelta dell' equidistanza delle isoipse in un bacino calancbivo. Unpublished Degree Thesis, Bologna.

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