Traces of these marshes still exist after two thousand years of cultivation, and in the very earliest times they must have presented a most formidable obstacle to travel. The one group which lies to the east of the valley of the Rother is still in part undrained; the other, which forms a mass of tidal creeks and inlets round about Hayling Island, Bosham, and Chichester harbour, is almost equally difficult. These two, then, set the limits of the county; for marsh is, of all obstacles, the most considerable at the beginning of a civilisation, as it is the least remembered in the height of one. It cannot be forded as can a stream, nor swum nor sailed upon; mere effort, such as that required for the climbing of mountains, is of no avail against it, and, whereas some considerable toil _will_ clear a track through a forest, and a track which, in our climate at least, can be maintained, once it is formed, with little labour, no such effort is of avail to primitive man in attempting to cross a morass. To drain it is quite beyond his power, and the formation of a causeway of hard land is, even in our own day, a most expensive and long process, as those readers who are acquainted with the history of our engineering will remember when they recall the building of the Manchester and Liverpool Railway across Chat Moss. It may be remarked in passing that there are scattered up and down England many examples of the difficulties which Fenland and bog present to an imperfect civilisation, and these are to be found in the “Stretfords,” “Stratfords,” “Standfords,” etc., which invariably mark a place where a hard Roman road was conducted across a river and its adjoining wet lands. In such places the straight line of the old Roman road can usually be traced, and one can also usually see how the modern road follows a devious track given to it after the decline of the Roman civilisation, when the imperial ways had been allowed to decay, and the half-barbarian traveller of the Dark Ages picked his way as best he could from one dry patch to another. These [Illustration: BOSHAM] deviations of the modern from the Roman lines across rivers and marshes in England are one of the most striking evidences of the gulf into which civilisation sank after the advent of the Saxon pirates. [Sidenote: DATE OF TOWNS]