Eustacy And Isostacy

In archeology, the term eustacy refers to the global level of the sea independent of the local factors such as the position of the sea surface with reference to the fixed datum as well as the center of the earth or the satellite in the fixed orbit around the earth. In the year 1888, the term eustatic was initially used by Eduard Suess and then in the year 1906, William Johnson Sollas translated the term.  In 1889, the term Eustasy was initially used by Clarence Dutton, who first spelled this term as eustacy, however as it was realized  that the Greek had no  the letter “C” the spelling of the term  was changed  to eustasy. Hallam drives this etymological view home by indicating that the ecstasy has no ‘c’ either.

Size of Fluctuations in the Eustatic Levels:

It is very difficult to find out the size of the differences in the eustatic position which occurred during the deposition sedimentary section. It is impossible to determine the size of the variations in eustatic position which happened during deposition sedimentary part.

Isostasy:

The term Isostasy is derived from the Greek word known as “ísos” which means equal and “stasis”, which means standstill.  It is the term which is used in the geology to describe the state of the gravitational equilibrium between the asthenosphere and lithosphere of the earth, therefore the tectonic plates float at the elevation that depends on their density and thickness.  This theory is invoked in order to explain how different topographic heights could exist at the surface of the Earth.  When some parts of the lithosphere reaches the state of isostasy, it is considered to be in the isostatic equilibrium.

Questionnaire:

• What is eustacy?
• What is isostasy?
•  Who coined the term eustacy?
•  Explain more about eustacy and isostasy?