what is sequence stratigraphy?

Answer 1

Sequence stratigraphy deals w/ the order in which sedimentary rocks are deposited during geologic time.

Sedimentary rock is deposited "flat". This is a general rule used in stratigraphy & is called the principle of original horizontality.

As mentioned in a previous post, sediments are deposited w/ the oldest layers on the bottom. This makes sense. If you collect newspapers and stack them daily, the oldest newspapers would be on the bottom.

However, events such as folding & faulting can overturn or lift strata which make the order of the rocks appear differently than when deposited.

The science of stratigraphy uses rules/guidelines to help determine the order of events during geologic time.

These rules/guidelines include but are not limited to...

1. Strata was deposited "flat".(principle of original horizontality)
2. The oldest is on the bottom & youngest is on the top. (law of superposition)
3. Newer rock (igneous) cuts across older rock. (principle of cross-cutting relationships)
4. inclusions - sometimes older pieces of rock are found in newer sedimentary rock. (You automatically know that the rock found inside it is older).
5. index fossils - some fossils can only be found in rocks of certain ages b/c they were only around for a 'short' span of geologic time.

It is pretty much like solving a geologic 'puzzle'.

Answer 2

Well I would say that FLIGHY answered it for you. The others (Kes and BabyBlue4ever_NC) have answered questions about stratigraphy, but not sequence stratigraphy which is a special subset of stratigraphy.

Go find a website about Sequence Stratigraphy and see for yourself what it is. One good one is this one at South Carolina:
strata.geol.sc.edu
or this one at Georgia:
http://www.uga.edu/~strata/sequence/seqStrat.html

Answer 3

If you pile boards on top of each other they are stratified and the lowest board was placed there first. Of course if a forklift truck overturns the bundled pile, the first boards are now on top. In either case there was a sequence in which the boards were placed or stratified.

If a large lake receives runoff from a glacier that melts only in the summer, new silt enters the lake each summer. Over the winter, the finnest silts gradually settle out and a distinctive series of stratified layers is formed. If geological events bend or turn over what originally were horizontal layers, close inspection should determine the original orientation and sequence.

When such layers also include fossils in the order of their extinction, that too will help determine the sequence of stratification. Because nature leaves a "written" record it is called sequence stratigraphy (as in sequence-write?).

Answer 4

Sequence stratigraphy is a relatively new branch of geology that attempts to link prehistoric sea-level changes to sedimentary deposits.

Answer 5

The original definition of a depositional sequence is by Vail et al., 1977 and states that
a depositional sequence is a stratigraphic unit composed of genetically related strata and bounded at its top and base by unconformities or their correlative surfaces
A depositional sequence is chronostratigraphically significant because it was deposited during a given interval of geologic time limited by the ages of the sequence boundaries where they are conformities, although the age range of the strata within the sequence may differ from place to place where the boundaries are unconformities.