Farouk El-Baz

Remote Sensing in Archaeology

Radar And Satellite Images.- Imaging Radar in Archaeological Investigations: An Image Processing Perspective.- Radar Images and Geoarchaeology of the Eastern Sahara.- Southern Arabian Desert Trade Routes, Frankincense, Myrrh, and the Ubar Legend.- The Use of Interferometric Synthetic Aperture Radar (InSAR) in Archaeological Investigations and Cultural Heritage Preservation.- Detection and Identification of Archaeological Sites and Features Using Synthetic Aperture Radar (SAR) Data Collected from Airborne Platforms.- Putting Us on the Map: Remote Sensing Investigation of the Ancient Maya Landscape.- Creating and Perpetuating Social Memory Across the Ancient Costa Rican Landscape.- Spaceborne and Airborne Radar at Angkor: Introducing New Technology to the Ancient Site.- Aerial Photography and Fractals.- Remote Sensing, Fractals, and Cultural Landscapes: An Ethnographic Prolegomenon Using U2 Imagery.- Geographic Information Systems.- Understanding Archaeological Landscapes: Steps Towards an Improved Integration of Survey Methods in the Reconstruction of Subsurface Sites in South Tuscany.- Remote Sensing and GIS Analysis of a Maya City and Its Landscape: Holmul, Guatemala.- Remote Sensing and GIS Use in the Archaeological Analysis of the Central Mesopotamian Plain.- Geophysical Prospecting and Analytical Presentations.- Ground-penetrating Radar for Archaeological Mapping.- Integrating Multiple Geophysical Datasets.- Ground Penetrating Radar Advances in Subsurface Imaging for Archaeology.- Landscape Archaeology and Remote Sensing of a Spanish-Conquest Town: Ciudad Vieja, El Salvador.- Urban Structure at Tiwanaku: Geophysical Investigations in the Andean Altiplano.- Geophysical Archaeology in the Lower Amazon: A Research Strategy.- Maritime Setting Applications.- Archaeological Oceanography.- Precision Navigation and Remotes Sensing for Underwaters Archaeology.- Cultural Resources and Heritage Management.- Applications of Remote Sensing to the Understanding and Management of Cultural Heritage Sites.

Physics of desertification

Report on Workshop on Physics of Desertification.- Desertification of Arid Lands.- Wind Versus Water Erosion in the Context of Desertification.- The United Nations Organization and the Issue of Desertification.- The Impact of Desertification on Land Productivity in Sudan.- Desertification Problems in a Humid Region.- The Formation and Motion of Dunes and Sand Seas.- Two-Dimensional Analysis of Dune Profile and the Effects of Grain Size on Sand Dune Morphology.- Stabilization and Afforestation of Sand Dunes Through Biosaline Culture Technique.- Some Aspects of Sand Stabilization in Egypt.- Eco-Technique-Magic Formula for Reclaiming Desertlfied Semiarid Crop Land.- Monitoring the Sand-Moving Desert Winds.- Aeolian Activity as a Planetary Process.- On the Reddening of Quartz Grains in Dune Sand.- The Wind and Desertification Processes in the Saharo-Sahelian and Sahelian Regions.- The Advance Mechanism of Longitudinal Dunes.- Production of Dust.- Soil Erosion by Wind: An Overview.- Wind Erosion in the Interior Delta of the Niger in Mali.- Aeolian Processes and Features at Amboy Lava Field, California.- Aeolian Processes in the Environmental Wind Tunnel and in the Atmosphere.- Threshold Velocities for Dust Production.- Formation of Ripples, Dunes, and Antidunes in River Beds.- Saltation Threshold Mechanics.- Dust Production by Wind Erosion: Necessary Conditions and Estimates of Vertical Fluxes of Dust and Visibility Reduction by Dust.- The Aeolian Wind Tunnel-Saltation Similitude.- Shape and Dimension of Dunes in Open Channel Flow.- The Stability and Propagation of Sand Ripples and Dunes.- Turbulent Flow Over Topography With Applications to Sand-Wave Development.

Distribution, Morphology, and Origin of Ridges and Arches in Mare Serenitatis

Lunar mare ridges and arches in Mare Serenitatis were mapped to understand better their mode of formation. Mapping of these features indicates that several pre-mare impacts in the Serenitatis area may be responsible for the localization of the circular ridge systems and that the subsurface, pre-mare topography is more complex than previously recognized. Apollo Lunar Sounder cross sections of ridge systems in southern Serenitatis indicate 50 to 100 m of local relief on these features. Ridges in the southwestern part of the basin mark the boundary of a bench 200 m above the local mare level. As reflected in their orientation, arches and ridges are possibly controlled both by rings of pre-mare basins resulting from impacts and by a more widespread global stress system. Small-scale features of ridges, such as medial lineations and lobate margins, do not conclusively define the origin of the ridges. However, estimates of crustal shortening from Lunar Sounder data and the coincidence of the major ridge system with the Serenitatis mascon suggest that ridges and arches were formed by gravitational readjustments of the mare fill along four probable impact structures and along a north-trending fracture pattern.

Tertiary-Quaternary faulting and uplift in the northern Oman Hajar Mountains

Field mapping and remote sensing investigations reveal two new major fault sets cutting through Tertiary rocks, Quaternary terraces and a several-hundred-year-old irrigation canal system in the Hajar Mountains of northern Oman. They extend for tens of kilometres, forming fracture intensification zones several hundred metres wide. WNW- to NW-oriented faults run parallel to the mountain fronts in the plains adjoining the central Hajar range then obliquely crosscut the mountains in the north. Motion along these faults explains how Quaternary marine terraces became elevated 190 m above sea level. A second fault set strikes north to NNE. The associated juvenile topography suggests that they also accommodate recent uplift, subsidiary to the WNW-striking faults, with minor strike-slip and differential movement between various segments of the Hajar Mountains. Both fault systems, and the amount of Quaternary uplift (between 100 and 500 m), are similar to those in other active and ancient forebulge environments. Using the fracture patterns observed, it is proposed here that the Hajar range lies on the active forebulge of a collision zone between the NE margins of the Arabian plate, the Zagros fold belt and the Makran accretionary prism, which resulted in the recent uplift.

Deserts and arid lands

1. The desert in the space age.- 2. A classification of dunes based on aeolian dynamics and the sand budget.- 3. Space observations of Saharan aeolian dynamics.- 4. Landforms of the Australian deserts.- 5. The sandy deserts and the gobi of China.- 6. Analysis of desert terrain in China using Landsat imagery.- 7. Aeolian landforms in the Taklimakan Desert.- 8. North American deserts.- 9. Natural resource survey and environmental monitoring in arid- Raj asthan using remote sensing.- 10. Landsat surveys of southeastern Arabia.- 11. Measuring spectra of arid lands.

Thicknesses of lunar mare flow fronts

Lunar near-terminator and high-resolution panoramic camera photographs were searched for flow fronts, the edges of flow units in mare areas. Data for twenty areas, including fifteen previously unmeasured areas, are summarized. Height measurements of flow scarps present on the Moon range from 1 to 96 m. More than half (57%) of all flow fronts measured are less than 15 m thick. These observations agree well with other photogeological and experimental observations of flow unit thicknesses on the Moon.

Neotectonics and fluvial geomorphology of the northern Sinai peninsula.

Abstract Large anticlinal ridges of Jurassic-Tertiary limestone in the northern Sinai Peninsula are part of the Syrian Arc Fold Belt, parts of which have been active intermittently from Late Cretaceous through the present. Recent uplift of the Syrian Arc Fold Belt is supported by quantitative indices of active tectonics including low values of mountain front sinuosity and, by recent seismicity, extending southwest past Cairo into the Fayoum Depression. The northern Sinai Desert has a climate similar to that of the adjacent part of the eastern Sahara. Sand sheets and dune fields cover its northwestern part, which is a depression extending from the Suez Canal to Wadi El-Arish. Numerous dry channels of palaeorivers and streams lead into this depression, where several temporary palaeolakes and flood overbank deposits have been identified. Some of the temporary pluvial palaeolakes developed behind natural dams formed by folds of the Syrian Arc, whereas others filled deeply-eroded fault traces. Migration of sand dunes may have blocked some channels, but the location of the dunes seems to be controlled by Recent uplift of parts of the fold belt, with the dunes residing in synclinal depressions and adjacent to fault scarps. The palaeolakes are correlated more with structures than with active dune fields. Wadi El-Arish abandoned a channel west of its present-day course, perhaps because of recent growth and uplift of the Gebel Halal Fold. This abandonment was synchronous with down-cutting of a gorge through Gebel Halal, which follows conjugate faults formed during uplift of an anticline. The presence of standing water during wetter climates in the past is supported by silt deposits and archaeological evidence of previous human habitation. The newly identified lake margin and fluvial sediments could be important targets for studying early-modern human and Neanderthal activities. In the eastern Sahara, cycles of pluvial periods that date back 320,000 years appear to correspond to interglacial stages. These indicate major global climate changes resulting in alternation of wet and dry climate episodes, which interplayed with local tectonic uplift to dramatically change the physiography of the northern Sinai.

DEM-optical-radar data integration for palaeohydrological mapping in the northern Darfur, Sudan: implication for groundwater exploration

North‐western Sudan, as a part of the eastern Sahara, is among the driest places on earth. However, the region underwent drastic climatic changes through the alternation of dry and wet conditions in the past. During humid phases, when the rain was plentiful over a prolonged time period, the surface was veined by rivers and dotted by large lakes. The new Shuttle Radar Topography Mission data (SRTM ∼90 m) revealed a large endorheic drainage basin, which is centred by a large terminal palaeolake, in the northern Darfur State. The use of GIS methods allowed the delineation of the drainage basin and its associated palaeorivers. The SRTM data along with the Landsat (ETM+) and Radarsat‐1 images corroborate the presence of segments of palaeoshorelines associated with the palaeolake highstands. These constitute a convincing argument of the long‐term existence of a possible pre‐Holocene large water body in the region in the past. The remains of the highest palaeoshoreline have a constant altitude of 573±3 m asl. At its maximum extent, the mega Lake occupied an area of about 30 750 km2 (the same size as the Great Bear Lake, Canadas largest lake), which would have contained approximately 2530 km3 of water. This, ancestral lake, which we named the Northern Darfur Megalake (ND Megalake), represents indisputable evidence of the past pluvial conditions in the eastern Sahara. The discovered palaeoshorelines will have significant consequences for improving our knowledge of continental climate change and regional palaeohydorology, and should be taken into consideration in studies of past human habitation in the region. Much of the water carried by the Northern Darfur palaeorivers and the ND Megalake would have percolated into the underlying rocks feeding the Nubian Sandston aquifer. These findings show that the used approach of space‐data integration can help significantly in the groundwater exploration efforts in the Darfur region, where freshwater access is essential for refugee survival, and can be successfully adopted in other parts of Sudan and arid lands in general.

Radar topography data reveal drainage relics in the eastern Sahara

The Shuttle Radar Topographic Mission (SRTM) elevation data reveal segments of inactive drainage channel systems in the eastern Sahara. Four sites are investigated and their drainage networks are delineated and compared with processed Synthetic Aperture Radar (SAR) and Enhanced Thematic Mapper Plus (ETM+) images. These include parts of the drainage lines that lead to the Kufra Oasis in Libya; the eastern Gilf Kebir drainage system that straddles the border region between Egypt and Sudan; the lower reach of Wadi Howar, the extinct western Nile tributary in Sudan; and a reversed flow channel of Wadi Kubbaniya northwest of Aswan in Egypt. These features are delineated using SRTM data and a Geographic Information System (GIS) hydrologic routine. The results show that the SRTM signals penetrate the desert‐sandy surfaces and map ancient drainage systems in the same way as SAR. The study also demonstrates that SRTM data can be used to confirm or modify pathways of channel courses mapped from radar images alone. Because of this capability, it is also recommended that SRTM data be used in place of GTOPO30 elevation data in hydrologic modelling of sand‐covered deserts.

Journey to the Gilf Kebir and Uweinat, Southwest Egypt, 1978

A multidisciplinary group of sixteen scientists visited the southwestern desert of Egypt to verify interpretations of Earth-orbital photographs. The two-week journey started at Kharga Oasis and proceeded south-southwest to Bir Tarfawi, west to the Gilf Kebir plateau, and then to Gebel Uweinat, on the border between Egypt, Libya and Sudan. Members ofthe expedition discovered sites of prehistoric human settlements ranging in age from approximately 3000 to perhaps 200 000 years ago. The condition of plant remains in the Gilf Kebir area indicated a prolonged period of dryness of up to 20 years. However, a cloud mass observed on a weather satellite image in mid-December 1977 may have provided rainwater for numerous plants in the Uweinat region. The geological findings, including prospects for economic mineral deposits, were valuable. Fluvial and aeolian erosional patterns were studied at Gilf Kebir and also at Uweinat. Many of the desert landforms display similarities to those recently identified on Mars. Correlations of features in the Egyptian desert with those on the Martian surface will help us to a better understanding of surface processes on both Earth and Mars.