At what time the use of iron began to be known among the people and when it superseded bronze is impossible to tell: the change must have taken place a long time before the ships of the Suiones were described by Tacitus, a wonderful example of the accuracy of whose description is found in the Nydam boat of which I will speak hereafter. Iron is very abundant in Sweden and Norway, and bog iron was no doubt plentiful in the islands of the Baltic; the use of the latter is proved by masses of slag, weapons, &c. found in the earliest graves of the iron age. The use of the bronze of the preceding period continued, and many objects of bronze are evidently of home manufacture. [Illustration: Fig. 163.—Cinerary deposit. Hole, filled with stones, 4½ feet deep, 3 feet in diameter.—Fyen. ] [Illustration: Fig. 164.—Cinerary deposit. Grave, 5 feet in diameter, 4 feet deep, lined with cobble stones, burnt bones, and broken fragments of clay urns.—Fyen. ] [Illustration: Fig. 165.—Cinerary deposit. Grave, 16 feet long, 6 feet wide, running from north-west to south-west, with hole 2½ feet deep, containing burnt bones and fragments of ornamented clay urns, remains of a large one-edged knife, &c.—Grönneskev field, Fyen. ] The earliest graves[119] belonging to this iron age in the North are called by Northern archæologists _depôts cineraires_ (cinerary deposits). These graves are round bowl-shaped holes, the excavations being from about two to four feet in diameter, and three to four feet deep: into these the remains of the funeral pyre, such as burnt bones of the corpse, ashes, charcoal, fragments of clay, urns, ornaments, jewels, other objects and weapons are thrown in, without order or method. The burnt bones and the charcoal are scattered sometimes over a bed covering a certain space, or sometimes in a heap together. In other graves the antiquities are found resting on the black mould itself. What were the causes which led to the temporary disuse of the mound-burials we cannot tell. Then came a period when after the burning of the corpse on the pyre the pieces of the bones were gathered into urns of clay, wooden buckets with metal mountings, vessels of bronze or glass bowls; these latter being very rare. These urns, &c., which are frequently found covered, for protection, by other vessels, were placed in chambers of varying sizes, those of the earliest graves being made of slabs, and just large enough to contain the sepulchral urn. It should be mentioned that the development of the form of these graves runs in an unbroken chain, beginning with the large grave chamber of the stone age, and culminating in the insignificant receptacles for preserving a mere handful of burnt bones. These graves are found sometimes singly, and at others in many hundreds, and even thousands, together.