The aim of this paper is to present the lithic surface collections assemblage coming from the private collection of Mr. Fossé. The geographic area covered by the prospector lies in the valley of the Ourcq river and the surrounding plateaus between the confluence with the Marne river and the limit of the department where the course of the Ourcq suddenly changes direction, but only the site of Brumetz is presented here. The assemblage, of which over one thousand artifacts were studied, is composed together at the same time of a production of flint Bartonian blades (blade cores, maintenance, breakdown products) and of a rich flake tools in which the tranchet is largely dominant. The richness and quality of artifacts collected allow to consider the existence of a new Villeneuve-Saint-Germain blade producer site, comparable to Ocquerre.