For instance, the road along the summit of the Hog's Back was a better road than the old track which follows the 300-feet contour upon the south side of the hill; but the summit road was a turnpike for many years during which the lower ill-kept lane was free, and hence a track which, since the Reformation, had served only to link up the little villages of Seale and Puttenham was used once more as a thoroughfare between Guildford and Farnham. A new stream had been diverted into the old channel, and this habit of avoiding the turnpike continued till a date so close to our own time as easily to bridge a gap which, but for that diversion, might have proved impassable. It is not without irony that a system whose whole object was to replace by new and more excellent roads the old rough tracks, proved, indirectly, one of the principal sources of their survival. The chalk, the third cause of that survival, is of such importance, and that importance is so commonly neglected, that it almost merits an essay of its own. Consider the various characters which make of this soil the best conceivable medium for the preservation of an ancient road. Like the sandy heaths and rocky uplands through which other primitive trails would naturally lead, it never paid to cultivate and therefore invited the wayfarer who was not permitted to trespass upon tilled land. But unlike other waste soil, it was admirably adapted to retain the trace of his passage. Long usage will wear into chalk a deep impression which marshy land will not retain, and which hard rocky land will never suffer. Compare, for example, the results of continuous travel along certain of the Yorkshire moors with that which will be produced along the Chilterns above the Thames valley. In the first case very marshy land, perpetually changing, alternates with hard rock. Unless some considerable labour were expended, as in the making of a causeway, neither of these would retain any record of the road when once it had fallen into desuetude. But on the chalk some trace would rapidly form, and with every succeeding year would grow more obvious.