CHRONOLOGY—RATE OF GROWTH OF CULTURE-STRATA. 55 
these three rates will come into quite close agreement, and stand 2.54, 2.50, 2.55. 
I have therefore taken 2.5 feet per century as the rate of growth of culture-strata 
in Anau city. 
The shafts sunk in Anau city found a very much looser earth than in the 
kurgans, so loose indeed that there was at times danger of caving. On the other 
hand, the kurgan strata are closely compacted and hard; they have evidently 
either grown at a considerably slower rate or have compressed in time by gravity. 
Perhaps both of these causes operated, but in any event, there is no doubt that 
the accumulation of a century is represented by fewer inches in the kurgans than 
in the city. The difference in texture and character is so very marked that I have 
taken a rate of 2 feet per century for all of the kurgan strata. 
Note.—In the winter of 1906-7 I visited Egypt in order to get some information as 
to the rate of growth of culture-strata in Egyptian village mounds. The places examined 
were the mounds which have grown up around the temples, in some instances nearly bury- 
ing them. ‘The excavation of the temples during the past few decades has left good sec- 
tions of these mounds. In these towns all constructions—houses, walls, etc.—were built 
wholly of unburnt bricks. According to their age these mounds now vary in height 
from 25 to 50 feet or more above the present level of the plain. ‘Their upward growth has 
been caused by the fact that all material for construction and repairs, and practically all 


“w 
Excavated Stratified debris + 

space 

of superimposed houses 


Sloping fan 



Fig. 20.—Explanatory Diagram of Village-mound Culture-strata at Medinet-habu, Thebes, Egypt. 
solid inorganic material that has been brought into the village from the beginning, has 
remained there. The bed of the Nile and the surface of the plain both rise at the rate of 
39 inches in ro centuries. The mounds (culture-strata) rise more rapidly. ‘Thus, while 
the base of a mound is always being buried, the elevation of the streets and of the house- 
floors of the village at the top is always increasing. The mounds consist, from top to 
bottom, of the standing walls of houses and other constructions, and of earth which, in 
more or less regular and compacted layers, fills the spaces which have been rooms, courts, 
and streets. In this earth is contained practically all the organic matter that through the 
centuries was consumed by the population, and its high content of phosphates and nitrog- 
enous salts gives it great value as a fertilizer. The mounds that have been bought in 
order to excavate the temples are for this reason being extensively exploited by the fellah- 
een for fertilizer. Fortunately for our purpose the fertilizing quality is largely confined 
to the earth instead of the walls; and the excavation of the former often leaves the walls 
standing, in places down to near the level of the plain. Observation shows that the growth 
of the mound is due to the combined rising of the level of the earthen floors, courts, and 
streets, through slow accumulation of earth and the mutual adjustment of all these factors 
to maintain a general level. The walls are continually becoming buried. When rooms 
become too low, additions are made to the top of the walls and a new roof is added. The 
products of wear and tear of the outer surfaces of the walls and of roofs by wind and occa- 
sional rains, go, together with abundant potsherds, to raise the surface of streets and 
