structures in the early times were made of wood probably plastered this way, which explains why in the southern part of New Mexico there are not now found higher standing walls of ruins or evidences of several stories.[206] Examples also have been seen in South-western Colorado, where a kind of wicker-work was built on the top of a wall and plastered on both sides. In the Salt River ruins the existence of the wood-work was indicated by the cavities left by its decay. There were also other structures built without the wattled frames. The cajon and pisé construction are very much alike, one being a Spanish and the other a French term, except that any pounded or rammed earth construction might be pisé, while the cajon is distinctly made by ramming earth into a box.[207] Therefore the _Casa Grande_ would be a clear example of cajon, while the Salt River construction of adobe rammed between the wattled frames would be pisé; and the plastered wicker-work would be jacal. The pisé and cajon method is very old all over the world. It is still to be found in France and England. In France the pisé box is about three yards long, one yard high, and about half a yard wide. The readiness with which the Amerind took advantage of his resources in the architectural line is again apparent in these great adobe structures of the Amerinds of northern Mexico and the South-western United States. It is not sensible, therefore, when some style of construction is discovered differing from that which we have been accustomed to see, to ascribe it to some mysterious race. [Illustration: TRANSVERSE SECTION OF AN ORDINARY YUCATEC BUILDING _f_, capstones of corbel vault; _l_, roof crest or comb. Such a building stood on the top of a mound W. H. Holmes ] [Illustration: W. H. Holmes FORMS OF THE MAYA CORBEL VAULT]