GlossaryPrint

Magdalenian

the last phase of the European Upper Palaeolithic, with a geographical representation covering a vast area of Europe, occupying the period from approximately 17,000 to 12,000 years before the present.

 

Magmatic rock

results from the consolidation of the magmas. While solidifying, depending on the conditions, especially pressure and temperature, magma can give rise to a great variety of rocks, which are divided in diverse types: plutonic, volcanic, and according to some authors, as dyke/sill rocks, in a final stage.

 

Mammoth

prehistoric extinct mammal, herbivorous, that appeared in the Pliocene (5 Ma) and disappeared nearly 12 000 years ago. It had curved trunk and ivory tusks, body covered with hair, could reach 5 m in height and weigh 12 tons. It was adapted to the cold environment that then existed to the north of the Northern hemisphere continents. It was an important source of food for prehistoric man. It became extinct probably due to the climate changes (warming of the planet) that took place at the end of the Glacial Era or Ice Age, and to mass hunting by humans who killed them for food and a variety of resources used to manufacture clothing, tools, lard, etc. The existence of Mammoth is not proved in Portugal.

 

Mastodon

prehistoric herbivorous mammal, belonging to the genus Mammut that lived during the Pleistocene (2.5/1.8-0.01 Ma) and became extinct about 10 000 years ago. It was about 3 m high, weighed approximately 7 tons and the ivory tusks reached 5 m in length. Humans hunted it for food. The mastodons differ from other mammoths by the format of their teeth, more conical and more adapted to the chewing of soft leaves.

Meseta

plateau-like geomorphological structure. It is a levelled high surface, originated by several erosive cycles that led to its flattening.

 

Mesolithic

prehistoric period, between the Palaeolithic and the Neolithic, that began about 12 000 years ago, with the beginning of the Holocenic, and ended with the development of agriculture.

 

 

Mesozoic Era or Mesozoic (251-65 Ma)

meaning 'intermediate life'. It is the second of the three major geological Eras (with three periods: Triassic, Jurassic and Cretaceous), also known as the “Age of Reptiles”. At the end of this Era, an important mass extinction occurred, related to meteorites falls and resulting climatic changes as well as tectonic activity outbreak and volcanic activity. Limestone units deposited during Jurassic and Cretaceous times in central Portugal were affected by dissolution and weathering processes, forming caves and rock-shelters, often occupied during Prehistory. 

 

Metamorphic rock

rock resulting from the transformation, in depth, from pre-existing rocks (sedimentary, magmatic or metamorphic rocks), when subjected to high temperatures and/or pressure. The changes result in the formation of new minerals and the acquisition of an oriented arrangement originating the schistosity.

 

Metamorphism

group of physical and chemical transformations, which usually occur at depth, effecting rocks subjected to high temperatures, pressure and fluid pressure. These processes produce rocks with minerals, texture and structure different from the original rocks.

Microlith

a small or very small stone instrument (maximum length not exceeding 40 mm and thickness no more than 4 mm), obtained most commonly by the segmentation or retouch of a bladelet.

 

Mineral

natural, solid or liquid substance, of well-defined chemical composition and characteristic physical properties. Minerals can be of magmatic origin, can result from chemical precipitation in an oversaturated solution or have biogenic origin (calcite from calcareous shells and exoskeletons). Minerals present great compositional variety and complexity in form.

Miocene (23-5 Ma)

geological epoch in which the continents continued the migration towards the current position: Africa bonded to Europe (±18 Ma), allowing the migration of African proboscids and cattle. Mammals reached their peak and Europe is marked by the arrival of the Hipparion (ancestor of the horse); Siberia and Alaska joined (±13 Ma), allowing the migration of different species. Climatic changes were registered cyclically, with variations in temperature, but in general, the climate was warmer and less humid than in the present.

Molluscs

terrestrial or aquatic habitat (marine or fresh water) invertebrate animals, of which oysters and squids are examples. They exist since the Cambrian, about 542 Ma.

Mousterian

name given to the period characterized by a style of stone tools (or industry) equivalent to the Middle Paleolithic (100 000-40/30 000 years). The Mousterian tools, made by Neanderthals, were mainly instruments on flake, such as points, scrappers and denticulate tools. The first funerary rituals, pendants and bone tools appear during this period. It is a period of cooling of the planet, corresponding to the last glaciation or Ice Age (Würm).

 

Muscovite

mineral of the mica group, usually transparent, yellowish or colourless. It is very common in granites.

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