When geology and archaeology attest to a historical record, it substantiates the accuracy of the account and increases one's confidence in the trustworthiness of the author. The findings of Mounts Ebal and Gerizim are significant for affirming the event of Israel's entrance into the Promised Land led by Joshua.

Historical Context

After the death of Moses and crossing the Jordan river (Josh 1:1-2), Jericho was conquered (Josh 6:1-5). In the defeat of Jericho, one Israelite "acted unfaithfully regarding the things designated for destruction" causing Joshua to fail in his initial conquest of the city of Ai (Josh 7:1-5). When Joshua learns of the sons of Israel's violation of the covenant, the violator Achan was judged for his disgrace of Israel (Josh 7:6-26). With the appeasement of God's wrath, the city of Ai is taken (Josh 7:26 - 8:2).

Against this background, Joshua builds an altar at Mount Ebal "just as Moses the servant of the Lord had commanded the sons of Israel, as it is written in the Book of the Law of Moses" (Josh 8:30). Moses' record of God's instruction included dividing the 12 tribes of Israel in half to stand on the two adjacent mountains Gerizim and Ebal (Deut 27:1-26). The purpose of this ceremony was to remind the nation of Israel of their covenant commitments, because their obedience was essential to stay in the Promised Land, or risk the consequences of disobedience as they just experienced.

And all Israel with their elders, officers, and their judges were standing on both sides of the ark before the Levitical priests who carried the ark of the covenant of the Lord, the stranger as well as the native. Half of them stood in front of Mount Gerizim, and half of them in front of Mount Ebal, just as Moses the servant of the Lord had commanded at first to bless the people of Israel. Then afterward he read all the words of the Law, the blessing and the curse, according to everything that is written in the Book of the Law. There was not a word of all that Moses had commanded which Joshua did not read before all the assembly of Israel with the women, the little ones, and the strangers who were living among them. (Josh 8:33-35)

Mount Gerizim - The tribes Simeon, Levi, Judah, Issachar, Joseph, and Benjamin affirm the blessings of obeying God's word.

Mount Ebal - The tribes Reuben, Gad, Asher, Zebulun, Dan, and Naphtali affirm the curses of disobeying God's word.

Geological Context

Mount Gerizim (Arabic: Jabal at Tur, height: 2890 ft) and Mount Ebal (Arabic: Jabal Aybal, height: 3084 ft) are the two highest mountains of Israel about 30 miles north of Jerusalem. In the valley between the two mountains lies the ancient city of Shechem now an archaeological ruin known as Tell Balata in today's West Bank as a part of the Palestinian city of Nablus.

The north face of Mount Gerizim, in a rain shadow, receives rain and at its base has a fresh water spring. Jewish tradition has seen the contrast of Mount Gerizim's fertile ground (Mount of Blessing) to Mount Ebal's barrenness (Mount of Curses) as figuratively presenting the Jew with a choice between good and evil.

Joshua records that half of the nation "stood in front of Mount Gerizim" and the other "in front of Mount Ebal" (Josh 8:33) to hear the Levitical priests say: "Be silent and listen, Israel! This day you have become a people for the Lord your God. So you shall obey the Lord your God, and do His commandments and His statutes which I am commanding you today" (Deut 27:9-10). After the pronouncement of each blessing (the people before Mount Gerizim) and curse (the people before Mount Ebal), each group was instructed to responded with "loud voice" in agreement by saying "amen" (Deut 27:15-26).

Does an area exist "in front" of Mounts Gerizim and Ebal where a person standing and speaking in the valley can be heard simultaneously on both mountains?

Halfway up, between the valley and the mountain top, each mountain exhibits a natural semicircular recess that mirror each other.

John William (J. W.) McGarvey (1829 – 1911), minister and seminary professor of the College of the Bible in Lexington, Kentucky noticed this while researching for his book: Lands of the Bible: a Geographical and Topographical Description of Palestine, with Letters of Travel in Egypt, Syria, Asia Minor and Greece. Philadelphia, PA: J. B. Lippincott and Company, 1881.

In his diary, JW McGarvey notes:

Our route took us back through the valley, and we resolved that while passing between the two mountains of Ebal and Gerizim, in the still morning air, we would try the experiment of reading the blessings and curses. It will be remembered by the reader that, in compliance with directions given before the death of Moses, Joshua assembled all the people on these two mountains, stationing six tribes on one, and six opposite to them on the other, and he stood between and read to them all the blessings and curses of the law (See Deut 27 - 28, Josh 8:30-35).

It has been urged by some skeptics that it was impossible for Joshua to read so as to be heard by the whole multitude of Israel. It is a sufficient answer to this to show that while Joshua read, the Levites were directed to repeat the words "with a loud voice" (Deut 27:14), and that it was an easy matter to station them at such points that their repetitions, like those of officers along the line of a marching army, could carry the words to the utmost limits of the multitude.

But it is interesting to know that the spot chosen by God for this reading is a vast natural amphitheatre, in which the human voice can be heard to a surprising distance. About half-way between Shechem and the mouth of the valley in which it stands there is a deep, semicircular recess in the face of Mount Ebal, and a corresponding one precisely opposite to it in Mount Gerizim. No man with his eyes open can ride along the valley without being struck with this singular formation.

As soon as I saw it I recognized it as the place of Joshua's reading. It has been asserted repeatedly by travelers that, although two men stationed on the opposite slopes of these two mountains are a mile apart, they can read so as to be heard by each other. We preferred to try the experiment in stricter accordance with Joshua's example; so I took a position, Bible in hand, in the middle of the valley, while Brother Taylor and Frank, to represent six tribes, climbed halfway up the slope of Mount Gerizim; and Brother Earl, to represent the other six tribes, took a similar position on Mount Ebal.

I read, and they were to pronounce the amen after each curse or blessing. Brother Taylor heard me distinctly, and I could hear his response. But Brother Earl, though he could hear my voice, could not distinguish the words. This was owing to the fact that some terrace-walls on the side of the mountain prevented him from ascending high enough, and the trees between me and him interrupted the passage of the sound. The experiment makes it perfectly obvious that if Joshua had a strong voice,--which I have not,--he could have been heard by his audience without the assistance of the Levites. As to the space included in the two amphitheatres, I think it ample to accommodate the six hundred thousand men with their families, though of this I cannot be certain. If more space was required, the aid of the Levites was indispensable."

With a semicircular recess midway up both mountains that forms a natural amphitheater, the unique characteristics of Mounts Gerizim and Ebal confirm Joshua's account of standing "in front" of Mounts Gerizim and Ebal in which everyone can hear the Levites reading of the Law from the valley. Moreover, it is remarkable that God prescribed this solemn and ceremonial reading of the Law for this location to Moses before the nation entered the Promised Land and knew of Mounts Gerizim and Ebal's existence.