Two years later Dr.Mook, of Wurzburg, published a work giving the results of his investigations, with careful drawings of the rude stone implements discovered by him in the upper Nile Valley, and it was evident that, while some of these implements differed slightly from those before known, the great mass of them were of the character so common in the prehistoric deposits of other parts of the world.
A yet more important contribution to this mass of facts was made by Prof.Henry Haynes, of Boston, who in the winter of 1877 and 1878 began a very thorough investigation of the subject, and discovered, a few miles east of Cairo, many flint implements.

The significance of Haynes's discoveries was twofold: First, there were, among these, stone axes like those found in the French drift beds of St.Acheul, showing that the men who made or taught men how to make these in Egypt were passing through the same phase of savagery as that of Quaternary France; secondly, he found a workshop for making these implements, proving that these flint implements were not brought into Egypt by invaders, but were made to meet the necessities of the country.

From this first field Prof.Haynes went to Helouan, north of Cairo, and there found, as Dr.Reil had done, various worked flints, some of them like those discovered by M.Riviere in the caves of southern France; thence he went up the Nile to Luxor, the site of ancient Thebes, began a thorough search in the Tertiary limestone hills, and found multitudes of chipped stone implements, some of them, indeed, of original forms, but most of forms common in other parts of the world under similar circumstances, some of the chipped stone axes corresponding closely to those found in the drift beds of northern France.
All this seemed to show conclusively that, long ages before the earliest period of Egyptian civilization of which the monuments of the first dynasties give us any trace, mankind in the Nile Valley was going through the same slow progress from the period when, standing just above the brutes, he defended himself with implements of rudely chipped stone.
But in 1881 came discoveries which settled the question entirely.
In that year General Pitt-Rivers, a Fellow of the Royal Society and President of the Anthropological Institute, and J.F.Campbell, Fellow of the Royal Geographical Society of England, found implements not only in alluvial deposits, associated with the bones of the zebra, hyena, and other animals which have since retreated farther south, but, at Djebel Assas, near Thebes, they found implements of chipped flint in the hard, stratified gravel, from six and a half to ten feet below the surface; relics evidently, as Mr.Campbell says, "beyond calculation older than the oldest Egyptian temples and tombs." They certainly proved that Egyptian civilization had not issued in its completeness, and all at once, from the hand of the Creator in the time of Mena.

Nor was this all.

Investigators of the highest character and ability--men like Hull and Flinders Petrie--revealed geological changes in Egypt requiring enormous periods of time, and traces of man's handiwork dating from a period when the waters in the Nile Valley extended hundreds of feet above the present level.