Hi I'm Misson Choudhury , A Post Graduate student, Graduated from Utkal university and Now pursuing my m.sc in applied geology at Bangalore university, Bangalore, i love geological mapping,drawing,hill climbing and tracking..

1. Event Stratigraphy
The ability to resolve the stratigraphic record of
Earth history is critical to understand past global
change events and the range of natural variability
within the global paleoclimate.
The geosphere – hydrosphere – atmosphere –
biosphere system operates on geologically very
short time scales and we must be able to resolve
the stratigraphic record of past events on similar
time scales if we are to understand the cause-and-
effect relationships operating within the system.

2. Global resolution ≤ 100 kyr is commonly
available when evaluating events from the
Cenozoic Era, but such resolution is less
common for older portions of Earth
history.
The introduction of High-Resolution Event
Stratigraphy (HiRES) more than two
decades ago revolutionized the ability to
resolve the Mesozoic and Cenozoic
stratigraphic records of global change, and
a similar revolution is currently underway
for the Paleozoic as well.

3. Here, we review the application of the
principles of HiRES to the Paleozoic
stratigraphic record with examples from the
Silurian System, discuss the quantification
of chronostratigraphic uncertainty, and
highlight the current deep-time Earth
history revolution that has the potential to
open the entire Phanerozoic record to the
evaluation of short time scale global climate
dynamics.

4. Event stratigraphy
Event stratigraphy comprises the study
of stratigraphical traces of relatively
short-lived events (instant to thousands
of years) compared to those normally
observed on a geological time-scale.
Events may be represented by
depositional, erosional or geochemical
features.

5. They may be of local significance
(e.g. a debris flow), or
 more extensive (e.g. a volcanic ash
deposit),
 or even global (eustatic flooding
surface).
 They may be random (dicyclic) or
regular (cyclic).

6. Virtually instantaneous events
(e.g. rainprints, footprints) are
mostly of local significance, but a
bolide impact may produce tektite
bands or isotopic excursions in
sediments covering wide areas.
 (tektite : a small black glassy object found in
numbers over certain areas of the earth's surface,
believed to have been formed as molten debris in
meteorite impacts and scattered widely through
the air).

7.  Other short-term events may record periods lasting from minutes to a few days,
 such as tempestites, (Tempestites are rocks which show evidence of a strong storm,
which has redeposited pre-existing sediments. They occur in shallow-water conditions,
because these sediments are disturbed and redeposited by the energy of waves).
 some turbidites (gravitational flow deposits), (A turbidite is the geologic deposit of a
turbidity current, which is a type of sediment gravity flow responsible for distributing
vast amounts of clastic sediment into the deep ocean).
 tsunamiites (tidal wave deposits), (A tsunami deposit (the term tsunamiite is also
sometimes used) is a sedimentary unit deposited as the result of a tsunami).
 lava flows and flood deposits.
 Medium-scale events (days to several years) include glacial varves and some flood
deposits.
 (glacial varves. varves that are deposited in a glacial lake and are the accumulation of
sediment transported by water at least partly from a glacial melt water source.
Variations in glacial varve thickness are mostly a function of variations of lake bottom
currents generated by glacial melt water input to the lake).

8. Palaeobiological events include
dinoflagellate or nannofossil blooms,
which provide regional markers and
may cause anoxic events.
Mass mortality may be represented by
unusually fossiliferous horizons (e.g.
some lagerstätten).

9. Long-term events (tens to several thousand
years or more) are represented by
palaeosols,
transgressive flooding surfaces,
hard grounds,
omission surfaces,
palaeomagnetic polarity reversals (about 3-
4 kyr duration),
most evaporite deposits and diamictons.

10. Evolutionary or migratory appearances of
organisms form the basis for
biostratigraphical event correlation (
biostratigraphy).
In the Quaternary setting the growth of
stratigraphy recognised from short-
duration, often highly characteristic
events has led to attempts to use these
features as a basis for correlation.

11. This event stratigraphy (e.g
Lowe et al., 1999), typically
includes changes of sea
level, climatic oscillations or
rhythms and the like.

12. These occurrences, often termed ‘sub-
Milankovitch events’, may be
preserved in a variety of environmental
settings and thus offer important
potential tools for high- to very high-
resolution cross-correlation. Of
particular importance are the so-called
‘Heinrich Layers’ which represent
major iceberg-rafting events in the
North Atlantic Ocean.

13. These detritus bands can potentially provide
important lithostratigraphical markers for
intercore correlation in ocean sediments and
the impact of their accompanying sudden
coolings (‘Heinrich Events’) may be
recognisable in certain sensitive terrestrial
sequences (summary in Lowe & Walker 1997).
The term stadial has been adopted for these
short-lived cold phases, whilst the intervening
warmer phases are referred to as interstadials
in the ice-core sequences (cf.
climatostratigraphy).

14. A further application of event
stratigraphy is in Illinois, in the
USA, where the Illinois Geological
Survey (a pioneer in the
application of formal stratigraphy
to the Quaternary) has adopted
this approach to the subdivision of
its glacial-interglacial sequences.