Museum of the Trovans

How were the Trovans formed and what are they?

The story of the Trovans

Imagine that over 100 million years ago, much of today's Oltenia was covered by water. Here, rivers poured down from the mountains, bringing with them sediments of various sizes (fine sands, small and larger gravels).

Block diagram - delta where the sediments were deposited from which the Trovans formed

The geological story of the Trovans begins more than 7 million years ago, when this area looked very different from what we see today: in the north-west of this sea, which was gradually filling with sediments, an ancient river created a delta, on the site where the Trovans Museum in Costești is located today. What makes these sediments special is that it was here that geologists first discovered these 'lumps' of sand and gravel, which they called trovans.

The rocks that grow...the local villagers say they are these trovans. And they're partly right. The geologists' scientific explanation is that trovans only form under certain conditions: where there are deposits of sand and gravel with high porosity and when water with dissolved minerals flows through the large space between the grains. Through crystallisation, over time these substances form a kind of cement that binds the grains together around their cores, and the grains continue to 'grow' into different sizes and shapes.

This process continues today inside the sand and gravel mountain at Costești.

Geology

The Trovans are wedged in sand strata of Upper Miocene (Lower Meotian) age, and the area is part of the Geotectonic Depression geotectonic unit.

The term "Trovant" is specific to Romanian geological literature and was introduced by Murgoci (in his work "Tertiary of Oltenia", 1907).

Trovans (greyish concretions) represent local cementations in the mass of the sands that contain them and the uneven cementation leads to different shapes of them, sometimes quite bizarre.

Geological Map of Romania 1:200.000, Pitesti Sheet, Geological Institute of Romania, 1978

Concretions are punctual agglomerations of mineral substance, with massive or concentric, zonal structure, formed diagenetically by centrifugal growth. After accumulation, clastic sediments (sandy deposits) change their internal organisation due to mechanical, biotic and especially chemical causes. In this way, selective cementation and diffusion structures give rise to trovans (greyish concretions). They are characterised by the degree of openness and communication of the interstitial space (porosity and permeability).

Geological map of Romania 1:50.000, Vanturarita Sheet, Geological Institute of Romania, 1978

The process of trovans formation is considered to be part of early diagenesis (syndiagenesis). At this stage of sedimentary evolution, transformations occur mainly under the influence of interstitial solutions. Due to the existence of fluids in the interstitial space, which is the fundamental prerequisite for chemical transformations, the process of cementation occurs.

In order to explain the appearance of cement in the pore space, cement that plays the role of binder of pre-existing clasts, it is taken into account that:

the direction, velocity and mode of fluid movement were controlled by pressure gradients and density differences;
the cement was deposited in the compressing sediment from solutions, the chemistry of which resulted from local interaction between the interstitial fluid and the pre-existing clasts;
factors controlling cement formation are: solution concentration, pH, Eh, system temperature, geostatic and hydrostatic pressure.

Thus, the composition of the concrements indicates the composition of the dispersed mineral phase and the conditions of the genetic environment (pH, Eh, presence of organic matter), and the structure and texture of the concrements (massive or concentric, micro or macrocrystalline) will reflect the conditions of precipitation in the sediment space (porosity, permeability, hydrostatic pressure, temperature).

The two essential conditions for the formation of trovans would therefore be as follows:

the existence of sandy sediments and the preservation of a large porosity despite normal compaction caused by pressure;
the presence of local (unevenly distributed) concentrations - 'segregations' - of specific minerals with secondary components dispersed in the host rock (carbonate fluids in sands).

Legends and stories

There are many legends ...and some tell of strange stones that, in the evening, hidden from people's curious eyes, talk, whisper, move... There are rumours that they are the eggs of extinct creatures, like dinosaurs, or that humans themselves carved them. They are said to be charged with positive energy or to grow every time after rain. These often bizarre shapes take on a wide variety of appearances: from dragon-like creatures curled up in a deep sleep, to wavy backs lazing in the sun, turtle shells and ram heads with ringed horns. You often feel like you're in a sculpture camp, but you're in the workshop of the most skilled craftsman of all: Nature. The workshop awaits imaginative walkers to discover the hidden enigmas of other Trovans!

The reservation

Costești Trovantilor Museum Nature Reservation has been administered since 2006 by the Kogayon Association, a non-governmental organization based in Costești, under a Custody Agreement signed with the Environmental Protection Agency of Vâlcea. The reserve was established by Government Decision no. 1581/2005 on the establishment of the protected natural area regime for new areas (position B.3.).

In accordance with the legal provisions and the obligations of the Custody Agreement, the Kogayon Association has drawn up a Regulation, a Management Plan and an Action Plan for the reserve, documents sent for approval to the Ministry of Environment and Forests, which regulate the activities to be carried out in its perimeter.

The main purpose of the 1.1 ha reserve is to protect the geological formations called trovans and it is located on the territory of Costești Municipality, Vâlcea County and was established on the basis of the approval of the Romanian Academy - Commission for the Protection of Natural Monuments.

The Trovanților Museum was established in 1996 by a team from the Faculty of Geology and Geophysics Bucharest - Society for the Protection of the Geological Environment, as part of a project to develop the area as an open-air geological museum. In the framework of this project, geological formations (trovans) were arranged in the area at the base of the sand quarry and information panels were erected in the perimeter and signposts on the road. Since then, no further work has been carried out in the area, and over time the panels have deteriorated or disappeared, some of the geological formations have been removed from the perimeter, others have been relocated. In the meantime, the quarry's sand mining continued, bringing other geological formations to the surface.

The relief of the area was shaped by man by opening the sand quarry into the hillside, without which even the trovans would not have been brought to light from the sand layers. The main geomorphological feature is the 30 m high cliff of the sand quarry on the eastern side of the reserve. Another, smaller (5 m high) cliff is located north of the reserve, towards the road. At their base, below road level, the land is relatively flat, with small bumps (sand mounds over which vegetation has grown. To the south of the reserve is a valley: the Sand Valley.

Since 2006, the Kogayon Association has been carrying out several activities in the reserve, mainly aimed at development, information and awareness-raising for locals and visitors, promotion, environmental education and maintenance.

The improvements made were: the installation of a bilingual information board, the maintenance of a resting place with table, benches and rubbish container, the marking of the boundaries of the reserve, the securing of the access with a barrier.

Costești Town Hall has set up a car park opposite the reserve, on the land where a tourist visit centre for the park, the reserve and the area is to be built and developed in partnership (Buila-Vânturarița National Park Administration, Costești Town Hall and Kogayon Association).

Boundaries of the reservation:

The northern boundary is the curved route of the D.N. 67 (Rm. Vâlcea - Costești - Horezu - Tg. Jiu - Drobeta Tr. Severin), between km 35 + 700 m - km 35 + 800 m;
The eastern boundary starts from D.N. 67, km 35 + 700 m, follows the upper part of the sand outcrop (quarry), along the beech forest border (private property), up to the stream of Valea Nisipului;
The southern boundary is represented by the winding course of the Sand Valley stream, over a length of 140 m; the boundary starts in the eastern part of the perimeter, from the point where the upper edge of the sand quarry/outcrop descends into the valley and then continues downstream along the stream to the wire fence (which constitutes the western boundary of the protected area);
The western boundary starts from the D.N. 67, at km 35 + 800 m and follows the fence (wire fence) separating the protected area from the neighbouring private property, up to the Sand Valley stream

Surface description:

The reserve comprises unproductive, uneven land and a sand quarry (outcrop) with western exposure, and is located in the outlying area of Costești, at the base of the Costești Hill (Zlamene), adjacent to D.N. 67. The reservation is part of the B Block, plot registered in the land register no. 148 of Costești Municipality, with cadastral number 313. The topographic parcel is surveyed on a scale of 1:1,000 in 2005 and has a total area (including the quarry) of 1.1 ha.