Se formaron por acumulación de sedimentos traídos por el viento, los ríos y el mar, que depositaron en zonas bajas aprovechadas, por ejemplo, para la práctica de la agricultura.
The frontiers when taken into consideration, maps which establishes the European frontiers were seen to appear from the 18th century only and not prior to that.
<u>Explanation:
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The ideology of formation of state or state boundary were emerged with the period of 17th century and even mid of 16th century witnessed it. The establishment of frontier though started with 18th century only.
The different topographical features were considered to describe the fronts such as the rivers, mountains. And, even the landmarks such as forts or towers were considered as the border distinction.
A Geologist studies rocks and minerals.
The volcanic ground it the most fertile kind of soil.
This is why many people live around them, even whey those volcanos still activated, like in Hawaii.
Bul the volcanos lave came from the core of the earth, and with millions of ears the get inactivated, this means they don't explode.
