Dalej and Prokop Valleys

The deep valley of the Dalej and the Prokop Brook from Řeporyje to its mouth in the Vltava including the slopes and hills above Hlubočepy, where the valley broadens, the Děvín and Ctirad hills and the Barrandov Rocks, form a unique area with a difference in elevations from 190 to 350 m above sea level. The major part is occupied by the Natural Park of the Prokop Valley including a number of minor protected areas. Actually it is a north-eastern projection of the Bohemian Karst situated outside the boundaries of the Protected Landscape Area of the same name. In the framework of Prague area it is a site with the concentration of the most varied natural phenomena and values ranging from world-known geological exposures with a wealth of fossils and marked ground formations to the still rich biocoenoses of rocky steppes, xerothermal and shaded rocks. There are also preserved remainders of thermophilous groves, as well as important archeological objects and some areas remoulded in the past by selective exctraction of various types of limestone. At present they form, particularly in the slopes above Hlubočepy, remarkable landscape scenery, disclosing illustratively the geological structure of the central part of the Barrandien.

Dalej and Prokop Valleys

The main rocks of the area are Silurian and Devonian limestones which determine the character of the whole area. In western part also basalt vulcanites (diabases) crop out, surrounding the local volcanic centre and forming such original rock formations as the Hemr Rocks. The sequence of Devonian limestones is interrupted by a layer of calcareous Dalej shales manifested in the ground by depressions and diversifying the relief of valley slopes. On the right-hand side of the valley near Hlubočepy there is also the youngest unit of Barandien Paleozoic - the Middle Devonian Srbsko strata of flysh character. Along the upper edge of the valley the remains of Cenomanian claystones and sandstones, possibly Tertiary gravelsands, have been preserved. Significant are also old kaolinitic sandy clays cropping out in the chasms of the White Clough. The Quaternary strata are represented particularly by the loess drifts, locally with fossil soils. At the Stydlá Voda spring calcareous tufa is still precipitating. All these rocks crop out in the steep slopes of the valley, formed mostly by Quaternary erosion.

Pedological conditions correspond with the diverse scale of fresh rock outcrops. Apart from various types of brown forest soils on mild slopes and in flat areas there are also marked areas of rendzinas and nutritive rankers on diabases.

The Prokop Valley has been covered with a mosaic of woods and open areas of karst steppe type since time immemorial. Forests could not develop fully because of ancient settlements connected with pasturing and agriculture. Only a hundred years ago the best part of the area had no forest cover. The only wood which has retained more or less its natural character is the Dalej Grove, particularly its eastern part. The initial oak and hornbeam woods have been preserved on the mild slopes facing the north, changing into scree and chasm woods with limes, maples and ashes on steep slopes. The plateau with the remainders of Cenomanian sandstones is covered with acid oak woods, the limestone edges are bordered with small rocks with solitary hairy oaks and cornelian cherry and a diverse undergrowth of such borderline species as the bloody cranesbill. Only fragments have been preserved of thermophilous hairy oak and cornelian cherry woods.

The wooded areas increased considerably in the course of the 20th century, on the one hand due to natural overgrowing with local wood species, on the other hand by extensive, but unsuitable planting of false acacia and austrian pine. Also some quarries with stony floors, such as U Jezírka, have overgrown naturally. Also bushes expanded considerably. Recently also large areas of former fields above the valley have been forested. Nevertheless rocky steppes still occupy considerable areas and are characterized by a wealth of xerothermal communities, comprizing thermophilous species, particularly the narrowblade grasses, semi-lignified shrubs and minor annual and bulb plants. On colder scarps and rocks communities with blue mountain grass prevail, generally considered postgacial relics.

The vegetation has been influenced by man since time immemorial. This is testified to by the communities with the clary (Salvia nemorosa) on the Butovice hillfort as well as ruderal vegetation on old spoilbanks and along roads. Some quarry faces, however, have overgrown with the original rock species, such as the montain alison (Aurinia saxatilis) on erect rock plates of the Vysoká. Unfortunately, only minute fragments have been preserved from the floodplain vegetation.

The Prokop Valley has been known always as a rich site of minor fauna, particularly insects and snails. From the number of vertebrates only current species can be found, known also from other parts of the Prague margin. Minor fauna has lost some species sensitive to suburban, particularly dust pollution. An example is the calciphilous snail Chondrina avenacea, known from a number of sites from Řeporyje to Děvín still in the middle of this century, but found only in the middle part at present. On the other hand, the Prokop Grove has preserved an isolated relic of sylvan zoocoenoses, suppresed on other sites as early in primeval times - a fact testified to by fossil finds.

Most woods have originated by recent forestation of open surfaces. The woods outside minor protected areas are managed as special-purpose suburban woods. False acacia has remained a problem, as it is very difficult to eliminate from protected areas and has contributed substantially to the ruderalization of large areas. Also modern planting of trees, often of monoculture type using, apart from wood species growing naturally in the hills of Central Bohemia, also the larch, red oak and austrian pine, with snowberry (Symphoricarpos) planted in undergrowth, cannot replace the ancient natural forest.

The Prokop Valley has been inhabited since time immemorial and its present appearance is the result of interaction of natural development and human interference lasting several millenia. The grazing of sheep and goats has disappeared entirely by now, although goats were kept here as late as the Second World War. Also cultivated fields have disappeared which were situated even on slope steps here and there. Work has stopped in numerous quarries which changed locally the appearance of slopes and have created entirely new landscape elements, such as the artificial canyon U Jezírka, the rock faces of the Vysoká or the Prokop quarry. An enormous spoilbank at the foot of the Prokop Grove, at present overgrown with wind-blown birch trees, originated during the Second World War.

In recent years whole housing estates and new roads have been built. The extent of older housing (Hlubočepy, Klukovice) has not changed much, but the activities performed by its population in the valley have disappeared.

The traces of limestone-processing industrial enterprises can be found almost in the whole area. These buildings and structures, usually adjoining the quarries, are out of operation at present; some were liquidated, others are used for different purposes. In the course and after the war some underground facilities were built here, while certain valuable sections, particularly the clough east of the Prokop Quarry, were partly filled with soil.

At present the whole complex is covered by a network of minor protected areas, the central core of which is the extensive nature reserve of the Prokop Valley. An important role is played by geological exposures some of which have the status of national natural monuments and comprise numerous fossils. In spite of considerable interference the Prokop Valley still ranks among the most valuable natural areas in Prague, but requires purposeful care and protection.

Modern housing estates have approached almost the very edge of the Prokop Valley.

Erect limestone strata exposed by quarrying have turned the Prokop Valley into one of the most beautiful landscapes in Prague area.

CONTENTS