The topography of Lebanon is divided by the Lebanon Mountains which run through the center of the country approximately NNE to SSW into slope on the Mediterranean side and Bekka Valley on the other side. The Lebanon Mountains continue from Jebel Ansarieh in Syria: to the southeast of Tripoli, they exceed 3,000m, and the main ridge averages throughout a height of over 1,500m. As shown in Fig. 2, this range contains steep mountains averaging 2,000 to 3,000 m, centering around Kornet es Saouda, the highest peak, to the southeast of Tripoli, continues on to Jebel Sannine, 2,600 m high, to the northeast of Beirut, then to Jebel Barouk, and Jebel Niha, east of Saida, ranging between 1,800 and 1,900 m. From Jezzine to the south, the altitude decreases sharply, and the range becomes the Palestinemountains of 500 to 700 m in height, with the gentle slopes. The eastern side of the Lebanon Mountains becomes Rift Valley, and the main ridge is situated the farthest east.

Fig.-2 The Summit Level Map of LEBANON, eliminating the Valleys less than 2km wide

Therefore, such rivers as Nahr Abou Ali, Nahr Ibrahim, Nahr el Kelb, Nahr Beirut, Nahr ed Dam our, etc. flow into Mediterranean, forming deep ravines. The coastal plain along the Mediterranean is narrow, and is found only around such cities as Tripoli, Beirut, Saida, Tyre, etc. It is on the coastal terraces where most of the residents live, which are more or less continuous, although they from only narrow land surfaces. The Rift Valley, which continues from the Dead Sea, Sea of Galilee and Hule lowland, loses its characteristics near Mt. Hermon, on the border of Lebanon and Palestine. At the same time it increases its height and reaches 1,000m after Marjayoun at Machghara in the south of Bekka Valley, while in the Dead Sea area it is 392 m below sea level (about -800 m, with about 400 m of water at its deepest), and -212m at Galilee (about -300 m, with the depth of water of 70 m). The width of Bekka Valley is 13 km at Qabb Elias, and is greatest at Baalbek, where it is 15 km. There the valley bottom maintains an altitude of 900 to 1,000 m, but it loses its altitude to 600 to 500 m when it enters the drainage basin of the River Orontes across the watershed to the northwest of Baalbek, and further on the valley reaches Bahr el Houmous in Syria (Fig. 5). The height of the main ridge of the mountains from the valley bottom is 1,400 m at Dead Sea, 1,000 m at Saghbine, 1,000 m at Zahle, and 1,200 m near Kornet es Saouda, where the fault lies toward the west. It is the Litani River which runs south, having the watershed to the northeast of Baalbek, and the Orontes River, which flows northeast. The Anti-Lebanon Mountains are highest in the western part, reaching 1,500 to 2,400 m, and gently slope inland. The block of Mt. Hermon at its southern part reaches 2,800 m high. Thus Lebanon Mountains and Anti-Lebanon Mountains run in parallel, and the mountain areas along Rift Valley constitute main ridges. This means that these mountains have been elevated by faulting, relative to the valley bottom.

Fig.-4 Cross-sections after E. Yaumas (1954) Fig.-5 Longitudinal Profiles

The general outline of geology in this area is shown in Fig. 3. Dolomite, limestone and basalt of Jurassic are exposed at elevations of 200 to 1,700 m, on the western slope of the Lebanon Mountains, forming Jabal Niha, Jabal Barouk and Hermon Mountains, and gently slope westward. Basalt was erupiea at the end of Jurassic and the beginning of Cretaceous, and is found alternately with limestone and dolomite. Especially is it limited to Jounie, east of Jbail, and upstream of Nahr Abou Moussa to the north of kornet es saouda.

Next oldest rocks are of the Cenomanien limestone, which accumulated as a result of transgression in the Cretaceous and is most widely distributed in this area, which forms the Lebanon Mountains and Anti-Lebanon Mountains, with a maximum thickness of about 1,000 m. Then orogenic movement of block movement occurred in a period from the end of the Cretaceous to the Eocene. Therefore, the Paleogene rocks are found only in the area from Bekka Valley to the low mountains of 300 to 700 m in height, to the east of Tyre.

In Neogene, intensive orogenic movement accompanied by folding and faulting began, and the Rift Valley was repeatedly thrust down. Therefore, the Bekka Valley was filled with deposit from many small rivers which flowed from the rising Lebanon and Anti-Lebanon Mountains. On the other hand, transgression occurred in the Mediterranean coastal region in the Miocene and Pliocene, and limestone of 300 to 400 m in thickness was deposited, forming Karst plateau at Ras ech Chaqaa area near Tripoli. Towards the end of the Pliocene this area became approximately like its present topography. The most characteristic thing in the Pleistocene was the activity of volcanoes, and there was basalt flow at Jebel ed Drouz in Syria. In the above-mentioned vicinity of the border to Palestine, where the bottom of Rift Valley rises sharply, such a basalt flow is also seen.

As a result of the change in the sea level, typical marine terraces have developed along the Mediterranean coast of Lebanon and Syria. They can be roughly divided into 3 or 4 terraces which were studied by DE VAUMAS (1954), FLEISCH (1956, 1962), BUTZER (1958), H. E. WRIGHT (1962), etc., and are correlated with the marine terraces in southern Italy. However, opinions are still not unanimous. The group of caves containing prehistoric remains, which is closely related to our present research, is distributed near the coast. The caves are from north to south, Ras Lados, Abou Halka, caves near Enfe, Es Stouh, Asfurieh, Ras el Kelb, Adioun caves, etc. These cave sites are situated about 10 to 15 m above sea level, and from a topographical view-point, such caves or shelters were formed by the erosion of the sea during the period when the sea level was stable for a certain period. Therefore, by doing careful research on these prehistoric sites, there is the great possibility of determining their relationship with the marine terraces, in other word, their geological age.