Sequence Stratigraphy Animated Gifs

AThis page represents a small library of animated Gif files describing various processes.

If you wish to view these animation in a series of steps save them to disk and view with a QuickTime player.

Sequence stratigraphy subdivides the sedimentary section into packages that are defined by bounding unconformities (Sequence Boundaries ) and internal surfaces that include the transgressive surface (TS) and the maximum flooding surface (mfs). The sedimentary geometries found within sequences are the products of changes in relative sea level and rates of sedimentation. The animated and annotated gifs below illustrate how changes of relative sea level and rates of sedimentation produce changes in the continuity and extent of the geometries of sedimentary bodies within each of the system tracts (Falling Stage System Tract, Lowstand System Tract, Transgressive System Tract, and Highstand System Tract and also show where and how the bounding and internal surfaces are developed for the sequence and for the systems tracts within it.

The animated gif above, models the Falling Stage System Tract. You can follow the position of the falling sea-level with respect to the evolving clinoform geometry (sea level position can also be tracked in the adjacent sediment supply and sea level position graph). The lower surface of this prograding wedge of sediment represents a sequence boundary. The shoreline can be seen to be forced to regress in response to the falling sea level and the high rates of sediment supply. The sediment surface lying just above sea level at the shoreline is subject to erosion. This Falling Stage System Tract is bounded at its base by an unconformity (a Sequence Boundary) and ends when relative sea level starts to rise and initiates the onlapping of the Lowstand System Tract that follows.

The animated gif above, models the Lowstand System Tract. You can follow the position of rising sea-level with respect to the onlapping, aggrading and retrograding geometry (sea level position can also be tracked in the adjacent sediment supply and sea level position graph). This particular model assumes that the Lowstand System Tract is represented by one onlapping parasequences. The shoreline can be seen to be retreating landward in response to rising sea level despite the high rates of sediment supply and this parasequence is overlain by a Transgressive Surface (TS). This Transgressive sediment surface lying at sea level at the shoreline is subject to erosion and forms a ravinement surface. The Lowstand System Tract is bounded at its base by the top of the downstepping clinoforms and ends when relative sea level starts to rise rapidly over the edge of the shelf, forming a transgressive surface and causing the sediments to onlap over the Falling Stage System Tract. Seaward, above the transgressive surface the sediment surface aggrades and each overlying layer becomes thicker than the previous layer, forming the Transgressive System Tract.

The animated gif above, models the Transgressive System Tract. You can follow the position of rapidly rising sea-level with respect to the onlapping and retrograding geometry (sea level position can also be tracked in the adjacent sediment supply and sea level position graph). The shoreline can be seen to be retreating rapidly landward in response to the rising sea level despite the high rates of sediment supply at the shore. The sediment surface lying at sea level at the shoreline is subject to erosion and forms a ravinement surface; offshore condensed section may form. The Transgressive System Tract is bounded at its base by the transgressive surface (TS) and ends when the rise of relative sea level slows and the Highstand System Tract starts to build seaward, downlapping onto the maximum flooding surface (mfs), and causing the sediments to prograde over the Transgressive System Tract.

The animated gif above models the Highstand System Tract. You can follow the position of the stillstand in sea-level with respect to the prograding and aggrading geometry (sea level position can also be tracked in the adjacent sediment supply and sea level position graph). The shoreline can be seen to be regressing seaward in response to the high rates of sediment supply at the shore and a relative stillstand in the sea level position. The sediment surface aggrades and each layer thins upward, i.e. it becomes thinner than the previously deposited layer. The Highstand System Tract is bounded at its base by the maximum flooding surface (mfs) and ends when relative sea level starts to fall rapidly and the Early Lowstand System Tract starts to build seaward, downlapping over the sequence boundary eroded during this change in base level over the Highstand System Tract.

The complete clastic depositional sequence of all the above animated Gifs is also available at
This complete cycle movie can also be viewed as a QuickTime movie