A few of the large streams may, when in flood, spr.ead out in a temporary shallow sheet qn a dead level of clay, or playa, in a basin centre, but the sheet of water vanishes in the warm season and the stream shrinks far up its course, the absolutely barren clay floor of the playa, impassable when wet, becomes firm enough for crossing when dry.

The creek was an impassable flood in winter but easily fordable in summer.

Steamers ply on both lakes, but the channel is rendered impassable by a rapid near the town of Tipitapa, at its northern extremity.

486 ordered the execution of similar repairs, the success of which is recorded in inscriptions, but in the middle ages it was abandoned and impassable, and was only renewed by Pius VI.

Wide swamps, deep morasses, tangled thickets, wild impassable forests, were their prevailing features.