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Introduction:
Scientific concepts, language and terminology go through changes over time. One of the most basic and important concepts in environmental and geologic science, which has gone through this change, is the term subsidence. The depth and breadth of change in the concepts related to this term is noticeable, although it has applications in other fields, even dentistry. Known as a geomorphological phenomenon, subsidence has turned into a theory on its own in geology and with its emergence it also outlined some other concepts and schools of thought in the field of geology. It also caused evolutions in common beliefs in this field. The term was first used in 1839 by Charles Darwin and since then it went through certain semantic and conceptual changes and brought around various registered and practical achievements. Taken from an experimental research carried out in the University of Isfahan, this study’s focus was on exploration of historical, conceptual alterations incurred to the term subsidence in geology. This study strives to determine the pattern of change in the beliefs of the scientists about a geomorphologic phenomenon, by tracking the conceptual changes inflicted on this term through time.
 
Materials & methodology
This is a study taken from an experimental research but falls, however, under the category of library research. We took out the reports written by fifteen prominent scientists in geology and geomorphology and grouped them into topics of geology, geomorphology, tectonics and hydrology, and then analyzed the historical evolution of the term in an analytical and comparative framework. The fifteen prominent scientists whose reports were used in this analysis and dissection are as follows;
Darwin (1839), Hall (1859), Dana (1873), Eshtile (1940), Key (1951), Adleman (1954), Lofgren (1963), Abovin (1965), Jennings (1966), Asemli (1967), Allen (1969), Gabridge (1984), Poland (1988), Cook & Dorencomb (1990).
In content analysis based on the organized observational and qualitative content description of the concepts, texts, and phenomenon, we first scrutinized and categorized the theoretical beliefs about the event of subsidence, using a comparative method and determined interpretative paradigm. Our analysis on these beliefs covered a 151 year timescale which was from the year 1839 to 1990.
Results
The concept of subsidence carries a semantic load peculiar to some common concepts.. In addition to explicating a great number of concepts related to the earth crust movement, it also makes its association clear with the animal life and tectonic phenomena. The term of subsidence was first used in geology literature and the realm of geological theories and made dramatic changes in the beliefs of geologists and geomorphologies.
The rise of concept of subsidence from the mysteries of nature helped scientists to answer difficult questions that were ever hardly possible to answer.
The concept of subsidence has always been considered by many scientists (Darwin 1839, Hall 1859, Dana 1873, Eshtile 1940, Key 1951). Lofgren (1873) attributes subsidence to extracting the underground water resources and mines such as oil and coil. Abovin (1965) also analyzed the occurrence of subsidence in geo-signals. Jennings (1966) introduced the dissolution in dolomite formations which is caused by human activities as the natural agent that triggers the event of subsidence.
Edelman (1954) and Asmly (1967) believed the earthquake of Mars, 1964, and the movement of the crust in large scale to be the main cause of the occurrence of subsidence in Alaska and the North Sea area, all as a result of human activities. Gabrysch (1984) introduced the pressure level decrease in Artesian wells and the receding of water in aquifers as the main cause of the occurrence of subsidence. Poland (1988) believed that a reduction in water level in Artesian wells and a time dependent increase of stress and pressure in the water sediments causes the subsidence to happen. Cook & Dorencomp (1990), considered natural and human related factors as the cause of subsidence.
We can conclude from this study, that

The concept of subsidence was first used by Darwin in 1839 in the domain of sedimentology and geomorphology and theoretically supported by the gradual convergence and uniformitarianism schools of thought.
The concept of subsidence has some theoretical load and should not be considered as just a pure geomorphologic event.
The concept of subsidence can be applied within the three domains of geology, geomorphology, tectonic and hydrology.

 
Discussion & Conclusion
The results obtained from the study about the evolution of the subsidence concept shows that it is used in academic setting as to be a phenomenon and that it also drags has the conceptual load of a theory. It’s The semantic load of this concept consists of mostly some common concepts that are used along with.
Hence we can say that;

The conceptual and semantic load of the term subsidence has not been fixed over time and is differently used by different scientists in different times.
The concepts that Darwin knows as ‘subsidence’ has important theoretical implications in a way that it changed the view of geologists about the earth life span and turned into a documented proof to support the theory of gradual convergence in geology.
The concept of subsidence in geomorphology mostly refers to exploiting underground aquifer water resources.
Translating the word ‘subsidence’ as sediment cannot reflect its real conceptual load and theoretical aspect and hence it is advised to use the original word subsidence in written text.