JOURNEY THROUGH MATTER

The rocks

The rocks that we usually come across on mountain paths are nothing other than aggregated minerals. They can differ in terms of colour, compactness, size and mineral composition, and are generally divided into three groups based on their origin.

Igneous rocks, also known as magmatic rocks, are formed by the cooling down of magma which can take place slowly inside the crust of the earth (in this case the rock is called intrusive) or rapidly by way of volcanic eruptions (eruptive).

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Sedimentary rocks are formed by the accumulation of soft sediments such as mud and sand, which are progressively covered by more sediment and then transformed into rocks by means of pressure, increase in temperature, and the dissolution and/or precipitation of minerals from surrounding saline solutions. Sedimentary rocks are characterised by stratification.

Within this group there are the CONGLOMERATES, rocks formed from gravel, the SANDSTONES, rocks made from sandy sediments, and the PELITES, rocks made from loam and clay.

These rocks are all known as TERRIGENOUS rocks because they are made up of the products of erosion of dry land.

Then we have the CARBONATE rocks, namely LIMESTONES and DOLOMITES, which are almost always of marine origin and closely associated with the activity of small organisms like corals, molluscs, bryozoans, echinoderms, foraminifera, algae or sulphate-reducing bacteria.

Furthermore we have the MARLSTONES, carbonate rocks with significant clay content, and the EVAPORITES, rocks formed from saline deposits following the evaporation of seawater.
The Dolomite Mountains are made up of mainly sedimentary rocks, with each subgroup present in varying degrees.

Metamorphic rocks are igneous or sedimentary rocks, the structure and composition of which are modified when they are buried in the earth’s crust, under conditions (temperature and pressure) very different from those of their origin.