The greatest artist on our planet: TIME
Rocks are objects of natural origin formed by the aggregation of several minerals. The minerals, on the other hand, are: "Any organic or inorganic substance, solid or fluid, chemically and physically homogeneous, with a clearly identifiable chemical composition, forming part of the terrestrial lithosphere, but also of other solid planetary bodies" (Note 1). rocks and the minerals that compose them are nothing but the result of a balance that is established between the chemical elements present and the environmental conditions in which these minerals (and therefore these rocks) find themselves over time.
It is not easy for a layman to understand the type of rock in front of him even if, with a little attention and a minimum of knowledge, something can be understood. For example, volcanic rocks have characteristic veins, kinks and even hexagonal prismatic structures caused by high pressures and high temperatures. If, on the other hand, we see a stratification it probably means that we are facing a rock of sedimentary origin.
How many times have we seen rocks that look like sculptures? This is the result of the erosions that take place over time so as to create works that man himself would not have been able to create. For example, a rock that is carried away by a glacier can be placed on a less hard rock. Over time it may happen that the rock on which the hardest stone has been placed is eroded by atmospheric agents and creates curious and extraordinary formations.
In nature, three types of rocks have been classified according to their origin and according to how they were formed: igneous rocks, sedimentary rocks and metamorphic rocks.
The rocks that are erupted from the volcano as lava that gradually cools and solidifies generate the IGNITE ROCKS (also called MAGMATIC ROCKS or ERUPTIVE ROCKS) from Latin ignis which means "fire" therefore rocks born from the fire that we find where there are volcanoes such as Etna in Sicily, Vesuvius in Campania, Mauna Loa on the island of Hawaii and many others. These are rocks that were formed by the consolidation of magma.
The rhyolites (or liparites), the trachytes and the andesites, the basalts, the granites, the diorites, the gabbros, the peridotites, the basalts and many others are magmatic rocks.
We report below some masterpieces of nature made with igneous rocks.
Elephant rocke, locality Castelsardo (province of SS - Sardinia - Italy)
Stone tree stone of the Eduardo Avaroa National Reserve of Andean Fauna in Bolivia
Elephant Rock, an elephant-shaped rock located on the Heimaeyi island in Iceland, born from the eruption of a volcano
The balanced rock, Chiricahua National Monument (Arizona, USA). Rock of volcanic origin
Giant's Causeway basaltic in nature located on the coast of Northern Ireland, about 3 km north of the town of Bushmills. It is an area that has about 40,000 basaltic columns with a hexagonal base that were formed following a volcanic eruption about 60 million years ago.
Another type of rock are the SEDIMENTARY ROCKS from Latin sederand "settle" that we can recognize from their stratification. In fact, these are rocks that are formed from the sedimentation of other older rocks that the atmosphere, water and other external agents have gradually worn down. Sometimes the layers of these rocks are regular and are flattened and one on top of the other. Other times we see them wavy, sloping or even vertical. This is due to the fact that the movements of the earth's crust have changed their original position.
Clay, sand, sandstone, gravel, conglomerate, clay, marl, siltstone, limestone and others are sedimentary rocks.
Also for these rocks, we report some masterpieces made by nature with sedimentary rocks.
Stone Mushrooms near Beli plas, a village in the municipality of Kardzhali, in the province of Kardzhali (Bulgaria). These are limestone formations.
Delicate Arch, sandstone formations located at the Arches National Park located near Moab (Utah - United States of America).
Sedimentary rocks of the Dolomites mountains (Italy)
White Desert. This is the Sahara El Beyda, where these incredible limestone and chalky rocks are found.
The stone forest or Shilin, an important grouping of limestone formations located in Shilin Yi Autonomous County, Yunnan Province, People's Republic of China
The third type of rock present on our planet are the METAMOPHIC ROCKS which are nothing more than rocks obtained from the transformation of the two previous rocks: igneous and sedimentary and also from the metamorphic ones themselves. Their formation usually takes place in the depths of the earth or in the mountains due to the strong heat and strong pressure.
Typical metamorphic rocks are: limestone, pyrite, quartz, talc, tourmaline, magnetite, kaolinite, graphite, marble. Here are some examples of what nature can do with metamorphic rocks.
Marble Cathedral in Patagonia (Chile), formed over 6,000 years ago by the slow erosion of the lake's waves on the marble walls.
Azure Window (Maltese: it-Tieqa Żerqa), also known as Dwejra Window. It was a natural limestone arch 28 meters high on the island of Gozo in Malta that collapsed in 2017 following a storm.
Limestone formations on the island of Koh Yao Yai in Thailand
Dr. Pio Petrocchi
Note1. From Encyclopedia Treccani,
23. Image licensed under the Creative Commons Attribution 3.0 Unported license. courtesy of Felix König