GlossaryPrint

Earth's core

corresponds to the innermost part of the planet, has a diameter of about 2 900 km and is basically made up by iron and nickel. The core is divided into a solid part (inner core) surrounded by a liquid one (outer core) which originates the earth’s magnetic field. Temperatures in the core reach 4 500ºC.

Earth's mantle

layer of the Earth’s structure situated between the crust and core, between depths of approximately 30 km (can be less in oceanic areas) and 2 900 km. The mantle is rich in iron and magnesium minerals, instead of the silica and aluminium minerals that predominate in the crust.

 

Elephas

one of two surviving genera in the order of elephants (Proboscidea) that exist from the middle Pleistocene (780 000 years). The genus has only one single living species, the Asian elephant, and ten extinct species.

Emigrant

individual that leaves his common living residence to settle in another country.

Emigration

spontaneous phenomenon of leaving a common living residence to settle in another country.

Emigration rate

ratio between the number of permanent emigrants in relation to the average resident population. It calculates “emigrants / resident population * 1000” and is expressed in permillage (‰) corresponding to the number of permanent emigrants per 1000 inhabitants.

Employed population

population working in a trade, profession or paid job (at least 1 hour/per day) and/or working in the company of a family member with he/she lives without remuneration or permanent salary (at least 1 hour/per day).

Eobasileus

extinct species of the Dinocerata mammal that lived in the Paleocene (65-56 Ma). It measured approximately 3 by 1.5 m and had 3 pairs of horns on its skull.

Eocene (56-34 Ma)

meaning 'recent dawn'. This designation is related to the emergence of modern mammalian faunas. In this Epoch of the Cenozoic Era, the continents continue their migration towards their current positions, the Tethys Ocean disappeared, and the elevation of the Alps isolated what remained from that ocean, forming the Mediterranean. India began its collision with Asia, giving rise to the Himalayas. Other continental collisions occurred, such as that which originated the Rocky Mountains (North America). The end of this epoch is marked by the extinction of various life forms, which can be related to the impact of a meteorite.

Equus

the only living species of several families of horses that appeared in the lower Pleistocene (2.5-1.8 Ma). It is a hoofed mammal (with only one functional finger), that descends from the Hipparion being, however, more robust and powerful. This species includes animals like the horse, donkey and zebra.

Erosion

corresponds to a number of physical and chemical processes involving the degradation and loss of cohesion of rocks. It leads to land relief degradation and smoothing. The main erosive agents are related to the water, in a solid or liquid state, stagnant or moving, and also the wind. These processes have originated or increased the deposits that preserve archaeological remains.

 

Experimental Knapping

method of studying stone tools that involves reproducing the technical processes used by prehistoric man to manufacture instruments. It also provides an understanding of the processes involved in the fragmentation of rocks, and establishes the criteria to recognize methods and techniques (percussion, pressure), and the nature of the hammer used (stone, bone, antler,…).

 

Extinction

total disappearance of species, subspecies or groups of species. Each geological Era is marked by a mass extinction episode. The most recent of these was the K-T extinction at the end of the Cretaceous period, responsible for the eradication of dinosaurs. The causes are multiple and inter-related (fall of meteorites, climate changes, episodes of intense tectonic and volcanic activity).

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