Be this as it may, with the second era begins something like a continuous history of our race. However scanty the marks of his tracks, we may feel sure that from this time forward man passed on one unbroken journey of development and change through the forgotten eras of the world’s life down to the dawn of history. We take the rudest condition in which we find man to be the most primitive, and we start with him in this new stone age as still a fisher or a hunter only. He first appears before us as depending for his nourishment chiefly upon the shell-fish on certain coasts of northern Europe. In the north of Europe--that is to say, upon the shores of the Baltic--are found numbers of mounds, some five or ten feet high, and in length as much, sometimes, as a thousand feet, by one or two hundred feet in breadth. The mounds consist for the most part of myriads of cast-away shells of oysters, mussels, cockles, and other shell-fish; mixed up with these are not a few bones of birds and quadrupeds, showing that these also served for food to the primitive dwellers by the shell mounds. The mounds are called in the present day kjökken-möddings, kitchen-middens. They have been chiefly found in Denmark. They are, in truth, the refuse heaps of the earliest kitchens which have smoked in these northern regions;[6] for they are the remains of some of the earliest among the polished-stone age inhabitants of Europe. So primitive are the weapons of the Danish kitchen-middens, that they have sometimes been classed with the old stone age implements. But I believe some traces of grinding if not of polishing have been found on them. And at any rate the mammalia contemporary with the kitchen-midden men are very different from those of the drift or of the caves.