Bordes discovered and first tested Pech de lAzé IV with a small sondage in the spring of 1952. In the following four years, 1953 to 1956, a dentist named B. Mortureux then excavated a larger trench, one by nine meters, into the site. He was stopped, however, by large blocks of roof fall and the demands of his practice. During the decades that followed, Bordes concentrated on Pech I and II, among other sites, and it was not until 1970 that he began excavating Pech de lAzé IV.
He spent a eight field seasons there, from 1970 to 1977, and opened a total of 52 square meters. In the first year, Bordes expanded Mortureuxs trench into the site making it approximately two meters wide and 11 meters long through the slope deposits in front of the limestone cliff. In the following years, he opened a rectangular grid of 7 by 6 meters against the cliff. Most of these squares were excavated to bedrock. At its maximum, against the cliff face, this meant a depth of roughly 6 meters. The principal layers, however, constituted a block of between 3 and 4 meters deep across most of the site (a block of squares on the western side of the grid - to the left in the photo above - were only partially excavated leaving a step of just under a meter).
In terms of the investment of his time and amount of material that he recovered, Pech IV represents the second largest excavation undertaken by Bordes during his career, second only to his work at Combe-Grenal.