Question

Traduccion de articulos cientificos de ingles a español !

Answer 1

Sedimentary rocks:
How are they formed and what do we
tell about the past?
Nicolás Pérez Consuegra, Andrés Felipe Cala Pérez


Sedimentary rocks:
How are they formed and what do they tell us about the past?
One of the main tasks of a geologist is to reconstruct the
from evidence that has remained on the rocks and the
fossil record. This task is complicated because it implies understanding
processes that happened dozens, hundreds and even thousands
of millions of years from evidence recorded in some
strata of sedimentary rocks. In addition, the rocky
complete, that is, not all geological time is recorded
in rocks, not all rocks represent the same scale of
geological time.
Sedimentary rocks (Figure 1) are important to reconstruct the geological history, since they are the
which preserve the evidence of life in the past (fossils) and the environments in which those organisms
they lived. These rocks are constituted by mineral grains or fragments of other rocks, which were ero-
sionados of some mountain by the action of agents like the water or wind. What was the weather like
when did the dinosaurs live? In the past were rivers or other bodies of water in regions
that today are desert, like the Guajira? What processes controlled the ecosystems of the past?
What kind of organisms lived in a certain area in the past? What mountain ranges existed in the
past? These types of questions can be solved only by the study of sedimentary rocks,
which includes field and laboratory analysis, such as petrography, chemical analysis and the study of
fauna and flora preserved in the rocks.

Each time the geologist goes to the field and sees a sedimentary rock,
he knows that he is facing a history of many pro-
geological processes, such as erosion, transport, deposition,
lithification of the sediments and subsequent removal of
the sedimentary rock, which today allows to find it on
the surface.
The cycle of a sedimentary rock begins, then, when the
sediment is generated: a fragment or mineral grain is dis-
from its parent rock and begins to be transported to
areas by the action of an agent such as the water of
a river, accompanied by gravity. During transport, the
sediments suffer physical abrasion, when hitting other grains
in their means of transport, which may vary from
canals to dunes. This causes the beans to
spending and its size will decrease with the distance
rrida. For this reason, the clasts, or coarser grains, tend to
to be found in the bottom of the rivers, near the mountains,
while finer sediments are common in areas
further away from the mountains. In addition, the action of
dissolved in the water can affect fragments of rocks or
minerals, to the point of transforming their composition. The place to
that sediment finally arrives is known as
basin
sedimentary