There is extensive evidence of subsistence intensification by Upper Paleolithic people in Europe, particularly based on the records from Spain, France, Belgium, and Germany. In addition to diversifying their subsistence base wherever and whenever possible, Upper Paleolithic hunters made efficient use of landforms and developed new types of weapon-delivery systems to procure large numbers of herd game. In so doing, they seem to have preferentially chosen to inhabit regions with significant hills and valleys. This allowed them to channel game movements and to hinder or trap herds, thereby facilitating mass kills. Specific physical features (rivers, cliffs, gorges, box canyons, blind valleys, etc.) were of proven use especially to late Upper Paleolithic hunters in their planned, scheduled mass kills of such species as horse, reindeer, red deer, bison, and ibex. The most dynamic component of Upper Paleolithic technologies was weaponry. New types of weapon tips, shafts, hafts, and propulsion devices were developed at an everaccelerating rate throughout the Upper Paleolithic and into the Mesolithic, between at least 35,000–40,000 BP and ca. 7000 BP.