what is unconformity in geologic terms?

Question

under stratigraphy

Answer 1

it is some unusual feature caused by erosion or some traumatic event like an earthquake.

Answer 2

An unconformity is any surface separating two units of strata of different ages. This indicates that sediment deposition was not continuous. This could be due to erosion, or simply a period on non-deposition.

The rocks above an unconformity are younger than the rocks beneath, unless the sequence has been overturned (by tectonics, folding).

An unconformity between parallel layers of sedimentary rocks, representing a period of erosion or non-deposition, is known as a "disconformity". In contrast, an "angular unconformity" exists where strata of sedimentary rock are deposited over tilted and eroded layers that may be either vertical or at an angle to the overlying horizontal layers. Another type of unconformity ("nonconformity") exists where sedimentary rocks overlie a previously eroded surface of metamorphic or igneous rocks.

Answer 3

all sedimentary rocks are assumed to be laid down roughly horizontally ie on the sea bed. As silt and other sediment settles out it eventually undergoes progressive burial, subjecting it to pressure and a little heat to form rock (lithification).
At some time in the past, plate movements and upwelling of the upper mantle causes the sea floor to rise, folding it into mountains if a collision between faults occurs, or simply plateaux, where this land is then subject to erosion.
If at some later point it is resubmerged and subject to more sedimentation, the emergent rock will have layers that are both different in sediment composition and in orientation. Land that is uplifted generally does so at an angle, and is lowered again at an angle, while sedimentation at the sea bed by its very nature will be on a more or less horizontal plane.

The upshot is this - if a rocky outcrop has layers running in different directions composed of (maybe) different material and it is not identified as an ancient sand dune or river system then it is most likely an unconformity.

Huttons unconformity is found on the scottish coast and it was this that brought the infant earth science to the fore.

Answer 4

I will give u the definition of unconformity.

Unconformity is a surface of erosion or non-deposition which seperates younger set of beds from the older beds.

Beds above and below the unconformity are of different ages.

There are different types of unconformity:

#Disconformity or Parallel Unconformity
#Angular Unconformity
#Non-conformity

Answer 5

Follow and read the information supplied by grpr1964 and saz 17. These are very interesting and great source of knowledge.

Answer 6

When one particular set of strata lie on a previously much earlier and weathered set of strata