Lakhasly

2.3.Cultivated Land

Cultivated Land is the eastern part of El Fayoum depression which characterized by good soil.Its surface is covered by lacustrine deposits with ground elevation less than 30 m above sea level (Figure 3).

2.3. Cultivated Land

Cultivated Land is the eastern part of El Fayoum depression which characterized by good soil. Its surface is covered by lacustrine deposits with ground elevation less than 30 m above sea level (Figure 3). The outlet of El Fayoum depression to the Nile Valley is a part of this unit which represented by a narrow path Known as "Ha- waret El Maktaa" between Gebel El Lahun and Gebel El Naalun. Through that path runs Bahr Youssef the main canal carrying the Nile water to the net of irrigation canals dissecting the El Fayoum depression floor. Reclama- tion projects are now under execution in the eastern peripheries of this land using Nile water in irrigation and create waterlogging problems in the neighboring old lands.

Geologically, El Fayoum and vicinities are occupied by sedimentary rocks belonging to Tertiary and Quater- nary Eras (Figure 4). The surface exposure has a thickness of about 848 m [1]. Quaternary deposits are distin- guished into, Holocene and Pleistocene deposits as follows:

The Holocene deposits are distinguished into; Aeolian deposits, young lacustrine deposits and young Nilotic deposits. Aeolian deposits are composed of loose quartz sand. Young lacustrine deposits are well defined in El Fayoum depression, associated with the lake development and composed of fine sand and clay with thin relics of gypsum and carbonate materials forming the agriculture soil. Young Nilotic deposits have a variable thickness (1 m to 12 m) as a result of the seasonal Nile floods and composed of silt and fine sand dominated by quartz grains and heavy minerals.

The Pleistocene deposits are differentiated into Old lacustrine and Old Nilotic deposits. Old lacustrine depo- sits (45 m thick) are present within the depression area in the form of terraces at levels +43 m, +30 m and +25 m indicating fresh water lake feeded by the Nile during the Pleistocene times. They consist mainly of clay, fine tomedium coarse sand with considerable amounts of calcareous and gypsiferous materials. They show high con- tent of mica, crystalline gypsum, iron, manganese oxides, sand debris, calcareous fragments and organic and fossil remains. Old Nilotic deposits (190 m thick) are recognized at the Nile-Fayoum divide where they are dif- ferentiated into terraces at levels +89 m, +112 m, +134 m and +167 m. They are composed of sand and gravels

forming a good groundwater aquifer. Tertiary deposits are differentiated into Pliocene Miocene, Oligocene and Eocene rocks as follows:

The Pliocene deposits (90 m thick) are defined in the Nile-Fayoum divide forming of fossiliferous sandstone

in some places overlain by Quaternary sand and gravels [11]. The Miocene rocks (20 m thick) are exposed at Gebel Qatrani to the north of El Fayoum depression overlying basalt exposures. They are composed of a series of alternating beds of sand and gravels with silicified wood re-

mains.

The Oligocene rocks (275 m thick) are encountered underneath the Miocene rocks at Gebel Qatrani area and capped by basalt sheet. They are composed of sand and sandstone with shale and marl interbeds. These rocks are rich in silicified wood and land animals (crocodiles, tortoises and turtles).

The Eocene rocks (390 m thick) have a wide distribution in El Fayoum-Wadi El Rayan area [10]. They are distinguished into Upper and Middle Eocene rocks. Upper Eocene rocks are formed of a series of escarpments overlooking El Fayoum depression from the eastern side. The rock succession is composed mainly of sand (69%), shale (19%) and limestone (12%) with high fossil content. These facies and faunal content indicate shal- low marine environment. The Upper Eocene rocks were distinguished into two formations, the upper Qasr El Sagha Formation and the lower BirketQarun Formation, both are dominated at the northern extremities of the cultivated land fringing Qarun lake and the hill mass of GaretGehannam on the west side of El Fayoum depres- sion. The thickness of both formations is about 180 m and 50 m respectively. On the other hand, Middle Eocene rocks constitute the oldest exposed rocks in El Fayoum area and its vicinities. They are represented mainly by limestone and marl with shale intercalations. They are discriminated into two formations, Raveine Formation and Wadi El Rayan Formation. The former appears below the alluvial deposits in the deep water channels and consists of gypseous shale, marl, limestone and sand. The other Formation is exposed at Wadi El Rayan where its outcrop composed of hard white limestone full of nummulitegizahensis, argillaceous sand and sandy shale.

Structurally, El-Faiyum depression is a structurally-controlled tectonic basin, marked by northeast-striking faults along its northern margin [18]. Qarun Lake is located in the northern part of El-Faiyum depression, at a right-step between two strands of the NE striking fault system. The E-W structures probably related to the rela- tive motion between south Europe and north Egypt and closure of the Neotethys [19]. The continuation of these faults in the present area is only detected from magnetic and seismic studies.

The area of study is a new reclaimed area located in the eastern peripheries of the old cultivated land in El Fayoum depression. Nile water is the source of its irrigation by lifting. Bahr Wahba bonded the study area from north and northwest and Bahr yousief and El Agooze canal from south and southwest respectively. It dominated by two famous Egypt's Pharaonic monument pyramids; Hawarah and Al-Lahun (Figure 2). These pyramids are exposed to different deterioration processes (aging) caused by internal and external stresses due to the mineral composition of the building materials, climate factors and groundwater rising. All the existing elements of the pyramids are constructed from mud bricks which consist of quartz, kaolinite, calcite, montmorillonite, micro- cline and gypsum, as well as Eocene limestone which consists essentially of calcite and small amounts of halite [20]. There are two types of cements: clay cement consisting of quartz, orthoclase, calcite and illite, jointing the wall's structure of the pyramid and gypsum cement consisting of calcite and traces of gypsum and quartz joint- ing the stones. Wasp nests from the pyramid consist of fine grains of quartz and calcite joined by wasp saliva, while the salts are halite and gypsum. The actual state of the building materials of the pyramid is poor; the mud bricks are more friable and the limestone is weakened and highly porous due to exposure to deteriorating factors. The area of study is covered by fractured white Fossiliferous Limestone interbeded by impervious layer (clay

and marl beds) and elevated than the surrounding old cultivated land.

Due to the traditional irrigation methods many dangerous lakes was formed and waterlogging appeared in the area causing serious damage in the new and old lands. Field observation shows that the land surface slopes to- wards these localities where, ground surface elevation reaches less than +30 m (Figure 3). These areas receive both return flow of irrigation water and groundwater from the surrounding parts where depths to groundwater reaches less than one meter and groundwater levels coincide with the land surface under these localities (Figure 5). As well as, the moisture is drawn up into the stones of ancient buildings through capillary action and the water table rises inside the Hawarah and Al-Lahus pyramids. Other factors such as the lack of advanced drai- nage system and the presence of impermeable sunie and clay beds at shallow depths raised groundwater to and near the surface at some localities forming waterlogging and surface water ponding (Figure 5), this phenome- non destroyed the majority of the new reclaimed areas and the Egypt's greatest monuments could be vulnerable with collapse if action is not taken.