Page:Prehistoric Britain.djvu/240

232 If we can obtain some measure of the time occupied, this should give us some approximate idea as to the length of the Neolithic period, and of the rate at which changes of the sealevel can take place."

After descanting on the rapid growth of forests and estuarine silts, he continues:

"It is useless to pretend to any exact calculations as to the time needed for the formaftion of these alternating strata of extensive silt and marsh-soil; but looking at the whole of the evidence without bias either way, it seems that an allowance of 1000, or at most 1500, years would be ample time to allow. A period of 1500 years may therefore be taken to cover the whole of the changes which took place during the period of gradual submergence. If this is approximately correct the date at which the submergence began was only 5000 years ago, or about 3000 "

Admitting that no change of sea-level has taken place in Britain during the last 2000 years, that the rate of submergence has been in the same localities of a uniform character, that the Essex Woman lived about 4000 years ago, and that eight feet of land-submergence has taken place during the 2000 years this movement was in action, it follows that the rate of submergence at Walton-on-Naze would be four feet per 1000 years. The same rate of submergence, if applicable to the Thames Valley, would make the Tilbury Man's age 10,000 years, and that of the commencement