Want of parallelism between strata in contact.
the surface of a stratum that represents a break in the stratigraphic sequence.
A boundary between two different rock sequences representing an interval of time during which new strata were not deposited and/or were eroded.
Unconformity - A substantial break or gap in the geologic record in which a rock layer is not overlain by another that is in stratigraphic succession; that is, a surface of erosion or non-deposition.
A substantial break or gap in the geologic record where a rock unit is overlain by another that is not next in stratigraphic sucession, such as an interruption in continuity of a depostional sequence of sedimentary rocks or a break between eroded igneous rocks and younger sediemntary strata. It results from a change that caused deposition to cease for a considerable time and it normally implies uplift and erosion with loss of the previous formed record.
A contact between two rock units of significantly different ages. An unconformity is a gap in the time record for that location.
the structural relationship between two groups of rock that are not in normal succession. to top
A boundary separating two or more rocks of markedly different ages, marking a gap in the geologic record.
A discontinuity in the succession of rocks, containing a gap in the geologic record. A buried erosion surface. See also nonconformity.
A time break in a depositional sequence.
a break or gap in the geologic record, as recorded in adjacent rocks.
A break or gap in the geologic record presented by rocks or sediments in a given location. Unconformities can be caused by an interruption in sedimentation and/or by erosion of previously existing rocks.
Surface between two rock units of different ages with different attitudes, represents an interval of time.
The relationship where the younger upper strata do not follow the dip and strike of older underlying strata.
Is when two rocks of different ages are side by side.
A break or gap in the geologic record, such as an interruption in the normal sequence of deposition of sedimentary rocks, or a break between eroded metamorphic rocks and younger sedimentary rocks.
a boundary between two adjacent geological layers where the lower layer was eroded away to some degree before the upper layer was deposited
a break or gap in the geologic record, where an older rock unit is overlain by a significantly younger unit following a period of erosion and/or non-deposition
a buried erosional surface and represents a time gap in the layers
a gap in the rock record, when either no deposition occurred, or there was erosion
a lack of continuity in deposition between strata in contact with each other, corresponding to a period of nondeposition, weathering, or, as in this case, erosion
an ancient erosion surface that can typically be found at the base of a major sedimentary basin
an irregular eroded surface that separates one set of rock layers from an earlier set
a stratigraphic feature that is formed by broad erosion of an area causing a significant gap to occur in the stratigraphic record
a supposed erosional surface between two adjacent rock formations, representing a time break of unknown duration between deposition periods
a surface in the rock record, in the stratigraphic column, representing a time from which no rocks are preserved
Landform. The line between layered strata of different ages representing an interval of time in which deposition stopped, erosion removed some material, and then deposition resumed. A period of time missing from the geologic record.
a major non-depositional or erosional break in the rock record. Three types of are normally recognized: Nonconformity - sedimentary rocks overlying igneous and/or metamorphic rocks; Angular unconformity with flat lying sedimentary rocks overlying tectonically tilted sedimentary rocks; and Disconformity with sedimentary rocks above and below the unconformity being essentially parallel to each other.
The contact between older rocks and younger sedimentary rocks in which at least some erosion has removed some of the older rocks before deposition of the younger. An angular unconformity shows that the older rocks have been deformed and eroded before the younger sedimentary rocks were deposited; there is an angle between the beds of the older and the younger.
A break in the geologic record, an interval of missing time due to nondeposition or erosion.
A discontinuity in the succession of rocks, which represents a gap in time and deposition. A surface separating younger rocks from much older rocks.
Lack of parallelism between rock strata in sequential contact, caused by a time break in sedimentation.
Large gap in the rock record, typically represented by a surface that bounds two rock or sediment bodies of vastly different ages.
a surface of erosion between rock layers that represents a missing gap in Earth history; a buried erosional surface
A surface separating two strata. It represents an interval of time in which deposition stopped, erosion removed some rock, and then deposition resumed.
Any interruption of the continuity of a depositional sequence.
break in the succession of geologic stratas owing to the lack of sedimentation, the erosion or tectonic movements.
a surface of erosion or non-deposition that separates younger strata from older rocks. It represents a missing span of time from the rock record.
a surface of erosion or non-deposition that separates younger strata from older rocks. This usually occur during periods of uplift or falls in sea level.
A surface of erosion or nondeposition that separates younger strata from older strata; most unconformites indicate intervals of time when former areas of the sea bottom were temporarily raised above sea level.
Surface separating younger from older strata, along which there is evidence of subaerial erosional truncation or subaerial exposure or correlative submarine erosion in some areas, indicating a significant hiatus. Forms in response to a relative fall in sea level. Note that this is a much more restrictive definition of unconformity than is commonly used or used in earlier works on sequence stratigraphy (e.g., Mitchum, 1977).
A break in the sequence of sedimentary strata. Often the unconformity surface is the result of erosion.
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe any break in the sedimentary geologic record.