In some instances the mound contained a circular stone wall, within which a pit had been dug to the depth of 2 or 3 feet in the original soil, as, for example, the one near Waukesha, described by Dr. Lapham.[7] A mound in Crawford County, opened by Colonel Norris, one of the Bureau assistants, in 1882, shows a similar vault or pit, but differs from the preceding in being distinctly stratified and wanting the stone wall. The construction of this tumulus and the mode of burial in it were as follows: [Illustration: FIG. 4.--Section of burial mound, Crawford County, Wisconsin.] Proceeding from the top downwards, there was first a layer of soil and sand about 1 foot thick; next, nearly 2 feet in depth of calcined human bones, without order, mingled with which were charcoal, ashes, and a reddish-brown mortar-like substance, burned as hard as pavement brick. This layer is numbered 4 in the annexed cut (Fig. 4), which represents a vertical section of the mound. Immediately below this was a layer about 1 foot thick (No. 3) of clay or mortar mixed with sand, burned to a brick-red color. Below this, in the space marked 2 in the cut, were found the bones of fifteen or twenty individuals, in a confused heap, without order or arrangement. Mingled with these were fire-brands, charcoal, and ashes. The bones were charred, some of them to charcoal, and some were glazed with melted sand. The mass appears to have been first covered with soft clay-mortar, which ran into and filled the spaces, and the burning to have been done afterwards by means of brush or wood heaped on the top, as among the bones were lumps of hard burned clay. The bottom of this layer corresponded with the original surface of the ground, but the excavation being continued, a circular vault or pit, 6 feet in diameter, was found extending downwards, with perpendicular sides, to the depth of nearly 3 feet. The bottom of this pit was covered to the depth of an inch with fine chocolate-colored dust. Although the filling of this pit was chiefly sand, there was a cavity at the bottom a foot high in the center, over which the sand filling was arched as shown in the figure. It is evident that the skeletons in this mound were buried after the flesh had been removed, as we can on no other supposition explain the fact that the clay or mortar had filled the interstices between the bones, and that in some cases it had even penetrated into the skulls. Another mound, opened by Colonel Norris in the same neighborhood, presented some peculiarities worthy of notice, although not sufficient to mark it as belonging to a distinct type. [Illustration: FIG. 5.--Section of burial mound, Crawford County, Wisconsin.]