Geology - Clime - Hydrography Print
SOIL
 

The current landscape inside the Park is very similar to the typical southern Maremma landscape, with gentle hills and valleys. The mountains to the South of Grosseto, which are known as Uccellina Mountains, represent almost totally the area of the Park. These mountains are bordered by the Tyrrhenian sea to the West, while the remaining part is delimited by alluvial plains of the rivers Ombrone and Albegna.
From a morphological point of view, in the central and northern area, the Uccellina Mountains are characterised by ridges which run towards North and North West and South and South East, and which reach the highest point near Lecci Mountain (Poggio Lecci: 417 metres above sea level) and High Mountain (Poggio Alto: 391 metres above sea level). They carry on to the southern part of the Park, where the altitude goes from 280 metres above sea level to 30 metres above sea level near Raso Hill (Poggio Raso), in the vicinity of Talamone. The central hilly area arrives to the sea (Cala di Forno) and from here carries on to Talamone little town, which also represent the southern border of the Park. In the Northern Western part the mountains border the areas of the dunes and beyond the dunes (Paduletto and Grand Duchy Pine Wood- Pineta Granducale). In this part of the Park the coast is low and characterised by the scheme dune immersed beach in the middle-under the marine beach.

 

 

MORFOLOGY 

High coast is characterised by rocky cliffs which arrive directly to the sea. This type of cliffs in Italian are called Falesie as they touch the sea in a vertical position and are not covered by vegetation, as the result of the direct and indirect action of the sea. Their formation can be divided into four phases:


 

1. erosive action of the waves
2. formation of a little rut with head
3. collapse of the rock above
4. moving back of the coastal line

This typology is visible in the central and southern area of the Park (Cala di Forno) and is called Falesia Viva as it is lapped by the sea and subjected to erosion; the northern part (Castel Marino) is instead characterised by another type of falesia (Falesia Morta) as this is separated from the sea by coastal deposits.
Along the slope there are many caves which represent forms of erosion of an aborted falesia. Their origins are probably due to sea erosion of rocky portions more or less fractured. The grottos are generally near calcareous rocks and can therefore be linked to a genesis of different types of phenomenon of karstic dissolution.

The landscape of the coast is mainly characterised by COASTAL DUNES ( Dune costiere) which
represent the most important form of accumulation of sandy sediments. They are determined by the deflation of the beach during which the sand is transported until the reduction of the speed due to friction determines their deposition. They do not have a typical shape as they are classified according to their position; their shape, height, and extension depend on the direction of dominant winds and vegetation.
 

The movement of the water and the action of the winds determine the formation of little ripples (a few centimetres high) on sandy shoals and on beaches. They are part of the transversal dunes and have an asymmetric shape, with the side facing the wind generally less inclined than the other. On the side facing the wind the sand is pushed up; the wind blows the sand forward from the ridge until it falls down on the opposite side and it is laid down according to the angulations of the rest of the sand (30 centigrade).

The mouth and terminal part of the river Ombrone are inside the protected area. The deposits of Ombrone alluvial plain are characterised by two main units. The oldest one (around one hundred thousand years old) is formed by sandy clay containing little pebbles and Macigno Breccia. The sand is rusty red, sometimes with bright tonalities, while the clasti are rusty black.
The other unit (ten thousand years old) is characterised by a mixture of polygenic and heterometric pebbles immersed in a muddy and sandy mould, recent deposits and clays, partly of anthropic nature as a result of the reclamation works.

Studies on the territory have pointed out that a huge erosion occurred in 1954-1985, has determined the moving back of the coastal line, near the mouth, of 480 metres, and its transformation from a delta to an estuary.
This phenomenon implies an interconnection of fluvial and marine processes. In particular, in the case of river Ombrone, it is important to remember:

  1. The diminished supply of fluvial material.
  2. The action of the currents and waves. The waves tend to send the sediments away due to the phenomenon of refraction during which they concentrate their energy towards promontories rather than in the bays and caves of the coast.
  3. Disappearance of Posidonia prairies from the bottom of the sea, due to pollution and excessive fishing which have made the movement of the sand from the bottom of the sea more dynamic.
 

The Uccellina Mountains are characterised by areas of Mesozoic and Tertiary periods (250-25 million years ago) which were part of the so called Tuscan Series (Serie Toscana).
The formations that can be recognised are:

  • VERRUCANO
    A detrital formation partially metamorphosed of siliceous nature characterised by conglomerated, and arenaceous parts facies, whose colour goes from light grey to pink
  • CAVERNOUS LIMESTONE
    This is characterised by limestone and dolomitic limestone whose evident cavernousness is due to the actions of karstic dissolution. The colour goes from light grey to black.
  • SOLID LIMESTONE
  • PSEUDOVERRUCANO
    Detrital nature. Different from Verrucano for the presence of one arenaceous conglomerated facies and a calcareous and detrital one.
  • TUSCAN SCAGLIA
    A formation represented by an association of various lithologies among which limestone and limestone with marble are the most important ones.
  • MACIGNO
    Arenaceous parts with intercalations of clay and quartz whose colour is light grey when the fracture is fresh and dark yellow when the fracture is altered.
    From a structural point of view, the Uccellina mountains, like all the mountains in Southern Tuscany, derive from two processes of which one, dating back to forty and twenty millions of years ago, was due to the collision with the lithosphere stratum.

 

CAVES

CLIMATE 

 

Alberese Weather Station (see picture) provides us with the correct information concerning the weather conditions in the Park. Weather wise, the important element to consider is the Eliofania which, for Grosseto Weather Station, varies from a minimum of 3.2 hours in December to a maximum of 10.9 hours in July, and which has an average value of 6.5 hours. This last value is very near to the maximum values in Italy, which can be found on the Tyrrhenian coast as a result of good air linked to the general circulation of the atmosphere. As a consequence of the amount of sun in this area, the yearly average temperature is 14.5 Centigrade with average values of 7.1 Centigrade in January and 23.1 Centigrade in August.
The values concerning the amount of rain fall show a maximum of 99.9 millimetres in November and a minimum of 16.9 millimetres in July with a yearly total average value of 667 millimetres. The rain period is concentrated between October and December with 37% of the total rain fall occurring in this period. During the dry months the rain is below 2 millimetres; in the Grosseto Plain (Pianura di Grosseto) the value is 4 and in Albegna Plain is 3.
In the last ten years the rain fall has been scarce, with the consequence of the decrease in the water resources. This phenomenon has been recognized to have in the whole of Southern Tuscany a rate of around 1.4 millimetres every year.

 

 

RIVERS, LAKES AND STREAMS
 

 

Rivers, lakes and streams - Inside the Park there are two types of water ways: the first is characterised by a way of secondary water courses, which are mainly artificial and created after the reclamation of the plain. They are mainly flat and have manufactured banks, such as Essiccatore Principale Canal of Alberese (one of the biggest ones) to the North, and Solco di Collecchio to the South. The second one runs along the mountains and is characterised by small water courses which are mainly streams.
The water areas inside the Park are very near the coastal path and, like all the coastal water areas, are in communication with the sea, and the movement of the layer is therefore obstructed by the inverted current of salty water. This creates the phenomenon of buoyancy of the water of layer on the sea layer. This equilibrium is interrupted by emungimenti (in Italian) in the northern and southern extremity of of the area of the Park, which cause the coming back of sea water and the rising of the area on interface.
The rising of sea water is also due to the rising of the average sea level, mainly due to the subsistence of the plains; this is caused by the stratification of non-consolidated sediments and excessive extraction of underground water.
Beside this, there is also a contamination of water of layer with mineral water of deep origins, like the type with sulphur and alkali (characterised by sulphur, chloride, calcium and magnesium) probably connected with the upward movement of the water along the faults, near Alberese, which also contributes to a visible thermal anomaly (37 grades).

The origin of river Ombrone is in the South–East side of the hills of Chianti, near Castelnuovo Berardegna (Province of Sienna - Siena). Up to the confluence, Arbia river (fiume Arbia)) runs towards the North and the South, and then turns abruptly Westwards, between Buonconvento and Montalcino. It carries on from this point, still keeping the directions towards the North and the South, with a straight movement up to the border between the provinces of Sienna (Siena) and Grosseto, which is where the river begins to move towards North East and South West, up to its mouth. For the first 40 kilometres it has the characteristics of a stream, with a small amount of water which increases dramatically after the confluence with the river Arbia. Merse, Orcia, and Trasubbie are among its affluents. Near the mouth it has a total length of approximately 160 kilometres and a basin of around 3500 squared kilometres.

The origin of river Albegna is in Mount Buceto (Monte Buceto: 1152 metres), in Grosseto province, and comes into the Tyrrhenian sea in Torre Saline, in Albinia area, without entering into Orbetello Lagoon, but remaining a few hundred metres far from it. It is 66 kilometres long. In Albegna high valley there is Rocconi Natural Preserve which covers an area of 371 hectares with the addition of an adjacent area of 253 hectares. The territory occupied by the preserve is characterised by hills, which are 200 metres high above sea level, in the Southern area (Fosso Paradisone) and have an uneven morphology. Whilst the Northern area is characterised by mountains which can be up to 500 metres high above sea level. In the whole area there are high walls of solid limestone at whose bottom part the rivers Albegna and Rigo run, sometimes creating deep and suggestive gorges.