The abrupt rocky hills of Israel admit of but few sweeps of valley between. There are valleys at Hebron, and S.E. of Gerizim, and between Gerizim and Ebal, and between Gilboa and Little Hermon the undulating and English like valley of Jezreel. Five Hebrew terms are so translated. Emequ, always rendered "valley," a long broad sweep between parallel ranges of hills, such as the valley of Jezreel. Gay or gee', the deep hollow S.W. and S. of Jerusalem, Ge-Hinnom; implying an abrupt, steep, narrow ravine, from a root to burst, a gorge formed by a burst of water.
Nachal, a wady or wide stream bed in winter filled by a torrent, but in summer dry and strewed with water worn stones and shrubs; KJV translated it also "brook," "river," "stream"; Biqu'ah, a plain wider than a valley, the wide plain between Lebanon and Anti-Lebanon is still called Bequa'a (Joshua 11:17; Joshua 12:7), and Megiddo (Zechariah 12:11). Ha-shephelah, wrongly translated "valley," a broad tract of low hills between the mountains of Judah and the coast plain (Deuteronomy 1:7; Joshua 10:40). The 'eemeq, "valley," of Elah in which Israel and the Philistines pitched is distinguished from the (gay "ravine" which lay between the armies (1 Samuel 17:2-3). Shaveh in Genesis 14:5 is a dale or level spot. "Bottom," metsullah (Zechariah 1:8), is a dell or shady bottom.
The use of the words 'eemeq and gay assists in the identification of Ai with Khirbet Haiy, one mile E. of Mukhmas (Michmash), which the survey of the Israel Exploration Fund favors. If Sennacherib invaded Judaea from the E. as did Joshua, he would naturally come to Khirbet Haiy. Thus all the places enumerated in his approach to Jerusalem (Isaiah 10:28-32) are visible from Geba exactly in the geographical order given in Isaiah, "Aiath, Migron (i.e. 'the precipice'), Michmash." Khirbet Haiy also suits Joshua 8:11-13, "the Israelites pitched on the N: side of Ai; now there was a valley (gay) between them and Ai ... Joshua went that night into the midst of the valley" (emek). The "plain" N. of Khirbet Haiy suits the Hebrew creek. The gai is either the ravine between the liers in wait and Ai, or else the bed of the watercourse in the creek. (Israel Exploration Quarterly Statement, July 1878, p. 132.)
Fausset, Andrew Robert M.A., D.D., "Definition for 'vale' Fausset's Bible Dictionary".