Before entering upon the subject of this article, the distribution of these remains in the county demands a few words. They are most numerous in the mountainous region which lies north of Ashbourne and Wirksworth, and west of Tansley, Darley, and East Moors. They are rarely met with in the more gently undulating country to the east and south. Why this should be is not altogether clear. It is probable that the valleys and the low-lying lands generally, which are now the most populated, were in prehistoric times too swampy for habitation; but this does not explain the general absence of prehistoric remains from the higher tracts of the lowlands of Derbyshire. It has been suggested that the primitive inhabitants clung to the more mountainous regions because of the ease with which they could be defended against the marauding incursions of other tribes. It is more likely, however, that agriculture is mainly responsible for the uneven distribution. The fertile higher tracts of the lowlands have long been under cultivation, whereas many of the Peak uplands still remain in the primal state of nature, and many more of them have only been wrested from that state within the last two centuries. One of the earlier effects of the enclosing of the wastes in the eighteenth century and earlier decades of the following century, was the removal of the large stones of ancient monuments for gate-posts, and the despoiling of stone tumuli for the construction of field-walls and roads. Even on the moors it is rare that these remains have escaped partial demolition for the sake of their materials. If the havoc wrought during two centuries in the sparsely inhabited Peak country has been so great, it is not surprising that few prehistoric remains are to be seen where the land has been for a much longer time under cultivation. Probably the relative abundance or scarcity of stone is also to some extent accountable for the distribution. In the Peak, where stone is plentiful and rock-fragments strew the ground, cairns or stone tumuli abound; but in the south, where clays, marls, and glacial deposits abound, and stone is only obtained by quarrying, the few remaining tumuli are of earth. Earthwork, if left alone, is wonderfully enduring, but is highly susceptible of being levelled, and so obliterated, by the plough. The plough cuts through it as easily as through the natural soil; whereas in the Peak may often be seen the stony bases of cairns, covered with brambles, and avoided by the ploughman.