Glacis: The steep smooth wall inside the excavation square protected Jerusalem in the Second Temple Period. A volunteer uses both hands to keep from falling down into the pit. The stratigraphy (different layers of debris laid down one after the other in later periods) may be clearly seen on the right side of the excavation square. The glacis itself consists of an outer layer of beaten earth (terre pisee) which we see in the picture, and alternating layers of pebbles and earth beneath. This glacis was found above the Gihon Spring in area G near the crest of the hill. The excavators expect that sealed beneath this 15–20 feet thick glacis are the remains of the Israelite period. At the top of the picture, we see an underlayer of the glacis. Immediately behind the standing man is an Israelite wall from the First Temple period.