18 BULLETIN, PUBLIC MUSEUM, MILWAUKEE. [Vol. III. 



builders to be rid of any pollution which might be conceived to be 

 attached to the surface soil, before starting the bed of sacred earths 

 upon which to place the remains of the deceased. 



Frequently the excavation extended several feet below the sur- 

 face of the surrounding land, sometimes going down as far as the 

 clay subsoil. This excavation was then carefully filled in with sacri- 

 ficial earths upon which the burial, crematory altar, or other special 

 feature was placed. This custom of excavating fairly deeply the 

 bottom of such a mound may have arisen through the necessity of 

 providing ample vertical space for the elaborate stratification re- 

 quired by the ceremonial procedure of these people. 



This practice of excavating the bottom of a mound is even more 

 strikingly shown in the construction of the effigy mounds. In fact, 

 perhaps the most important development in the work on this mound 

 group is the discovery that in certain instances the builders of these 

 effigies first made an excavation of approximately the same animal 

 form as the mound itself and extending to a considerable depth be- 

 low the surface of the surrounding earth. They then built, stratum 

 upon stratum, with much ceremony, as was indicated by the suc- 

 cessive strata of sacrificial earths and fires, the mound which we 

 now find reared above the surface of the ground. This we may 

 consider as a cameo above the original excavation which has been 

 termed an intaglio. (See plate IV and fig. 5.) 



In filling in an intaglio excavation, or in fact in constructing 

 almost any type of mound in this group it was built up, with various 

 layers of ceremonial earths, common soils, and fire blackened strata. 

 Indications point to the fact that a considerable time may have 

 elapsed, at least in some instances, between the construction of one 

 stratum and the placement of the one next succeeding it. It is pos- 

 sible, in fact, that such a mound may have required a considerable 

 period of years 9 for its completion, and that each stratum of fire 

 blackened earth may mark a ceremonial cycle in the construction of 

 the mound. An analogous mortuary custom is found in the annual 

 mourning ceremonies of certain Pacific coast tribes which are even 

 yet celebrated 10 . In accordance with the usual aboriginal psychol- 

 ogy this seems to be a more likely mode of procedure than that a 

 large number of individuals should go and build such a huge earth 



9 See footnote 4. 

 10 The annual mourning ceremony of the Maidu is described by Dr. R. B. Dixon in 

 Bull. Amer. Mus. Nat. Hist., Vol. XVII, part 3, pp. 245-259, 1905. Similar ceremonies 

 are celebrated among the Miwok and certain other California tribes. 



