We extract some further particulars from Badeker's Syria and Palest. page 334.
"Mt. Gerizim rises to a height a little less above the sea-level than Mt. Ebal (which is 2986 feet high). It is composed almost entirely of nummulitic limestone (tertiary formation). The summit consists of a large plateau, extending from north to south, at the north end of which are the ruins of a castle. The building, as a castle, was probably erected in Justinian's time, although the walls, five to ten feet thick, consisting of drafted blocks, may possibly belong to a still older structure. The castle forms a large square, and is flanked with towers. On the east side are remains of several chambers, one of which has a Greek cross over the door. Near the burial ground to the north-east rises the Moslem wely of Skeik Ghanim, and on the north side of the castle there is a large reservoir. Of the church which once stood here, the lowest foundations only are extant. It was an octagonal building with an apse towards the east, having its main entrance on the north, and chapels on five sides. To the south of the castle are walls and cisterns, and there is a paved way running from north to south. Some massive substructions a little below the castle, to the south, are shown as the stones of the altar which Joshua Is said to have erected here (8:30-32). In the centre of the plateau the Samaritans point out a projecting rock as having once been the site of the altar of the temple. Over the whole mountain-top are scattered numerous cisterns and smaller paved platforms, resembling the places of prayer on the area of the Harana at Jerusalem. The whole surface bears traces of having once been covered with houses. Towards the east there are several paved terraces. At the south-east corner, the spot where Abraham was about to slay Isaac is pointed out. Near it, to the north-west, there are some curious round steps. The summit commands a noble prospect to the east lies the plain of El-Mukhna, bounded by gentle hills, with the village of Askar lying on the north side, and that of Kefir Kullinn on the south farther to the east is Rujib. The valley to the south is Wady Awarteh, to the east, in the distance, rise the mountains of Gilead, among which Neby Osha towers conspicuously. Towards the north the Great Hermon is visible, but the greater part of the view in this direction is shut out by Mt. Ebal. Towards the west the valleys and hills slope away to the blue band of the distant Mediterranean."
⇒See also the International Standard Bible Encyclopedia.
The following description of this memorable site is from the most recent and trustworthy account (Conder, Tent Work in Palest. 1:62 sq.):
"South of Nablus rises the rocky and steep shoulder of Gerizim. The mountain is L-shaped; the highest ridge (2848.8 feet above the sea) runs north and south, and a lower ridge projects westwards from it. The top is about 1000 feet above the bottom of the valley east of Shechem. As compared with other Judaean mountains, the outline of Gerizim is very fine; the lower part consists of white chalk, which has been quarried, leaving huge caverns visible above the groves which-clothe the foot of the hill. Above this formation comes the dark blue nummulitic limestone, barren and covered with shingle, rising in ledges and long slopes to the summit. The whole of the northern face of the mountain abounds with springs, the largest of which, with ruins of a little koman shrine to its genius, was close to our camp.
"In ascending to the summit of the western spur of Gerizim, by the path up the gully behind our camp, the contrast was striking between the bright green of the gardens, dotted with red pomegranate blossoms, and the steel-gray of the barren slope. Running eastwards and gradually ascending, we first reached the little dry stone enclosures and the oven used during the Passover. There are scattered stones round, but no distinct ruins of any buildings; the place is called Lozeh or Luz, but the reason of this appears to have escaped notice. The title is of Samaritan origin, and is due to their view that Gerizim is the real site of Bethel or Luz, the scene of Jacob's Vision.
"The highest part of the mountain is covered by the ruins of Justinian's fortress, built A.D. 533, in the midst of which stands Zenol's church, constructed in A.D. 474. The foundations alone are visible, showing an octagon with its entrance on the north, and remains of six side chapels; the fortress is a rectangle, 180 feet east and west, 230 north and south, with towers at the corners; that on the south-west being now a little mosque dedicated to Sheik Ghanim, who is, according to the Samaritans, Shechemn the son of Hamor. The fortress walls are built of those constantly recurring drafted stones which are often loosely described as Jewish or Phoenician masonry, though the practiced eye soon discriminates between the original style of the temple at Jerusalem, and the rude rustic bosses of the Byzantinles land Crusaders.
"A large reservoir exists, north of the castle which is called El Kul'ah in Arabic, and below this a spur of the hill projects, artificially severed by a ditch and covered with the traces of a former fortress. This is perhaps the station of the Roman guards, who thus prevented the Samaritans from approaching Gerizim, for it commands the north-eastern ascent to the mountain.
"Of the ancient Samaritan temple, probably the only relics are the remains of massive masonry known as the 'Ten Stones' ('Asherah Balatat), near the west wall of Justinian's fortress. They are huge blocks rudely squared, forming one course of a foundation, the north-west corner of which was laid bare by captain Anderson's excavation in 1866. There are two courses, and the lower one contains thirteen stones; this course, however, was not formerly visible, and the Samaritans considered ten stones alone to lie buried, and to be those brought from Jordan at the time of Joshua — thus supposing some supernatural agency sufficient to carry such huge blocks up a steep slope 1000 feet high, to say nothing of the journey from the Jordan. Under these stones, as before noticed, the treasures of the old temple are supposed to lie hidden.
"South of the fortress is one of those flat slabs of rock which occur all over the summit. It shelves slightly down westward, and at this end is a rock-cut cistern. The whole is surrounded by a low, drystone wall. This is the Sacred Rock of the Samaritans, and the cave is traditionally that in which the tabernacle was made. At the time of my second visit some peasants were using the Sacred Rock as a threshing-floor. Rude stone walls extend on every side, and farther south there is a curious flight of steps leading down east. They are called the 'seven steps of Abraham's altar,' and just beneath them, on the edge of the eastern precipice at the southern extremity of the plateau, there is a little trough cut in the rock resembling the Passover oven. This the Samaritans suppose to be the site of Abraham's sacrifice of Isaac, for their version of the story reads 'Moreh' instead of Moriah, and makes Gerizim the scene of the patriarch's trial." Full archaeological details may be found in the Memoirs accompanying the Ordnance Survey (2:187 sq.). SEE SAMARITANS, MODERN.