the nearer a place is to the point where silt is being deposited the
longer it must remain marshy, as the land last formed is always
more waterlogged. But this land changes in its turn and in time
becomes thriving.
Aristotle, writing of the Egyptian delta in his Meteorologica, believed that Egypt had once been a much wetter place that had for some considerable time been drying out. Aristotle had not visited Egypt himself, but he had at hand excellent observations in the works of Hecataeus of Miletus and Herodotus who had visited there in 550 BC and 450 BC respectively, and perhaps reports of other travellers as well, Egypt even then being a place of fascination to the Greeks and a common destination for both by tourists and merchants. Considering Egypt specifically and anticipating by more than two millenia the significant influence of the rise of sea level and the rechannelization of river deltas on human geography, Aristotle noted that "Rivers change their courses too, come into being and perish, neither are the same parts of the earth always moist, nor is the level of the sea always the same, but subject to recession and encroachment over time." As the Nile delta had grown drier, he said, the people had encroached from the higher lands to take up habitation in the floodplain as it was formed the evolution of the lower delta following the law that:
the nearer a place is to the point where silt is being deposited the
longer it must remain marshy, as the land last formed is always
more waterlogged. But this land changes in its turn and in time
becomes thriving.
The implication of this thinking is that Egypt has changed from a formerly wet marshy place to a dry one; in fact that is exactly the case as we shall see from archaeolgical and plaeoclimatic evidence of the early history of the Sahara.
As Aristotle saw it, the wetting and drying was, in the bigger
picture, part of a long term cycle for just as there is a
winter among the yearly seasons so at fixed intervals there is a great
winter and an excess of rain. Aristotle thought that these rare
pluvial events were not necessarily world wide but might be
confined to certain geographies, much as the great flood of Deucalion and
been mostly confined to the River Achelous in Old Hellas
(Met p115)
(Meteorologica, I, xiv.)
In this Aristotle accepted the view of Plato
who had concluded that the flood of Deucalion must have been an
event confined to river valleys and that not all humanity had perished
in that great flood. Thus Aristotle's description of the geographic process differs
little from what one might read today in stratigraphic descriptions of
the non-uniform, quasi-rhythmic character of deltaic
microstratigraphy. These and other of Aristotle's strikingly modern observations and inferences are far
closer to what modern climatologists suggest than they are to the
dominant uniformitarian approach of the last century which is
derived in large part from observations taken at high European latitudes.
(For examples of emerging thinking on this subject, particularly
the richer record of lower latitiude nonstationary paleohydrology see
Baker, Victor R, Paleoflood hydrology and extraordinary flood
events, Journal of Hydrology 96(1987)79-99, and A bright future for
old floods in Temperate Paleohydrology, L. Starkel, ed,
Wiley 1991.) Nonetheless even today Aristotle's views are rejected by many
establishment scientists.
However these established views do not necessarily reflect the
growing splinter group of earth scientists who are now vigorously
decrying the uniformitarian "Roman" precepts in favor of a
chaotic "Greek" standpoint; for example see the several excellent papers
in William Glenn's Mass Extinctions, Stanford University
Press, 1994, including the comment of Kenneth Hsu, a geologist of no mean
reputation: "Substantive uniformitarianism is the epitome of the
ignorance and arrogance of nineteenth century scientists." See
also Herbert Shaw's discussion of the storytelling "syntax" of
microstratigraphy, which Shaw compares to the syntax of language
or poetry (The periodic structure of the natural record, and
non-linear dynamics, EOS 68(50) 1651-64.) Shaw compares California's
historical earthquake discourse with James Joyce's fiction, notably
Ulysses.(Linguistic model of earthquake
frequencies appleid to the seismic history of california,
USGS open file report 87-296.)
