This is a tentative résumé of the work done on the preceramic horizons in Chicama and Virú valleys as a part of the Virú Valley Project of 1946. Before summarizing the results of excavations in the old midden deposits, mention should be made of the recent physiographic changes in the Virú Valley. These have a definite connection with the prehistory.

The drainage of the south arm of the valley starts at an elevation of slightly over 4000 meters with the two highest forks on the flanks of a 4200 meter peak. This section is today completely ice free, but as the general level for glacial moraines in this part of Peru runs between 3200 and 3400 meters, with one moraine in the Callejon de Huaylas down to 1800 meters, it is obvious that the physiography of the valley was once influenced by water either discharged directly from glaciers or draining from a greater area of condensation.