In the above sketch of the progress of scientific research into the terremare I have selected four typical examples for special description. We have seen that in one, viz. Montale, accumulated _débris_ stood as a clear mound on the surface of the surrounding plain, while that of Gorzano rested on a natural hillock. The Castione deposits also assumed the same form, but in this case the mound was only partially above the plain, the rest being buried in it. The tops of the piles found in its peaty stratum (_terra uliginosa_) were on an average 3 feet below the level of the present surface of the surrounding plain, and the lowest portion of this bed was a couple of feet still lower. In the fourth example, Casale Zaffanella, there was no mound at all visible, but on examination the remains of the settlement were found to be precisely similar to those of the others, only the mound was completely buried, as it were, in a sea of hardened mud. The explanation of this will be readily perceived when we remember that the amount of submergence respectively shown in these instances is in the inverse ratio to their distance from the lower parts of the plain and its great water channels. The yearly inundations of the Po and its tributaries extend far and wide, each time leaving a film of mud, by the repetition of which, in the course of ages, the surface of the plain has become considerably elevated. Thus, the increase of silt since the terramara settlement of Casale Zaffanella was founded, amounts to 12½ feet--a depth sufficient to cover the highest part of the mound. It is difficult to say how much this levelling up process is accountable for the scarcity of these stations in the lower parts of the Po valley. That they existed, however, in close proximity to the river is amply proved by those stations at Viadana, as well as one or two others, for example, at Brescello, in the Parmensian district, on the south side of the river. _Distribution._--Formerly the terramara deposits were supposed to be peculiar to the middle reaches of Parma, Reggio, and Modena; but later discoveries have upset this generalisation, as they are now shown to have a much wider distribution, embracing the provinces on both sides of the Po. (See Sketch Map, page 266.) [Illustration: _Distribution of_ LAKE DWELLINGS & TERRAMARE _in the_ PO VALLEY]