The Geography and Geology of South-Eastern Egypt

Chapter I. — Introduction 1

„ II. — General Description of South-Eastern Egypt 18

„ III. — Surveying Methods and Principal Geographical Results 39

„ IV. — The Wadis draining Westwards to the Nile 78

„ V. — The Wadis draining Eastwards to the Sea 94

„ VI. — The Mountains and Hills 164

„ VII. — Water Supplies 234

„ VIII. — Geology.—Sedimentary Rocks 251

„ IX. — Igneous Rocks 262

„ X. — Metamorphic Rocks 331

„ XI. — Tectonics and General Geology 354

„ XII. — Tribal Boundaries 366

„ XIII. — Notes on the Road from Halaib to Port Sudan 372

INDEX 379

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LIST OF PLATES. * * * * *

Plate. To face page

I. — Orographical Map of South-Eastern Egypt FRONTISPIECE.

II. — Sketch Map showing Drainage Basins 22

III. — Sketch Map showing Water Sources and Roads 26

IV. — Views of Ruins at Um Eleiga and in Wadi 30 Shenshef

V. — Views of Tomb of Sheikh Shadli and Bir Shadli 32

VI. — Map of the District of Nugrus and Sikait 106

VII. — Summit Views of Gebels Nugrus and Abu Hamamid 166

VIII. — Views from Gebel Migif 168

IX. — Descending Gebel Zabara 170

X. — Views from the Summit of Gebel Atut 172

XI. — Views in Wadi Muelih and of Gebel Selaia 172

XII. — Typical Views among the Mountains of Hamata and Abu Hamamid 176

XIII. — Views on Gebel Kahfa 178

XIV. — Views of Gebel Kalalat and the Summit of Gebel Faraid 192

XV. — Map of the District of Abraq and Abu Saafa 202

XVI. — Panoramas from the Summits of Gebels Niqrub and Gerf 206

XVII. — Map of the District of Gebel Gerf 210

XVIII. — Map of the District of Meisah and Wadi Di-ib 218

XIX. — Map of the District of Elba and Halaib 226

XX. — Geological Map of South-Eastern Egypt 250

XXI. — Geological Map of Ras Benas 258

XXII. — Acid Igneous Rocks 268

XXIII. — Intermediate Igneous Rocks 284

XXIV. — Basic and Ultra-basic Igneous Rocks 300

XXV. — Metamorphic Rocks 334

XXVI. — Sketch Map showing Tribal Boundaries 368

XXVII. — Sketch Map of Route from Halaib to Mohamed Ghul 372

XXVIII. — Sketch Map of Route from Mohamed Ghul to Port Sudan 372

LIST OF ILLUSTRATIONS IN THE TEXT. * * * * *

FIG. PAGE.

1. Sketch-map showing position of area described 1

2. Map of Abraq Springs 123

3. View from the summit of Gebel Elba 229

4. Granite of Gebel Fereyid 269

5. Red pegmatitic granite of Wadi Gemal 271

6. Biotite-granite of Gebel Abu Hegilig 273

7. Hornblende-granite of Gebel Elba 275

8. Hornblende-granite of Gebel Hamata 275

9. Granite-porphyry of Kreishim Hill 276

10. Quartz-felsite of the Wadi Huluz 277

11. Quartz-felsite from a dyke at Gebel Kolaiqo 278

12. Altered quartz-felsite of Gebel Igli el Iswid 281

13. Microperthitic structure in felspar of quartz-felsite of Gebel Hadarba 282

14. Fractured felspar crystals in crushed quartz-felsite of Wadi Huluz 282

15. Syenite of Gebel Zergat Naam 284

16. Syenite-porphyry of Gebel Zergat Naam 284

17. Trachyte from a dyke at Gebel Kahfa 285

18. Diorite of Gebel Allawi 287

19. Diorite of Wadi Baaneit 287

20. Augite-diorite of Wadi Um Hargal 289

21. Augite-diorite of Gebel el Anbat 290

22. Mica-diorite from a dyke at Gebel Abu Hegilig 291

23. Diorite-porphyrite of Gebel Abu Hodeid 292

24. Augite-porphyrite of Wadi Muelih 293

25. Kersantite of Gebel Fereyid 294

26. View near the top of Gebel Sufra 296

27. Andesite of Gebel Sufra 296

28. Gabbro of Gebel Dahanib 298

29. Gabbro of Um Eleiga 299

30. Hypersthene-gabbro of Hadal Aweib Meisah 300

31. Olivine-gabbro of Gebel Um Bisilla 301

32. Olivine-gabbro of Gebel Atut 302

33. Olivine-gabbro from hill S.-E. of Gebel Selaia 303

34. Troctolite of Gebel Um Bisilla 304

35. Pyroxene-granulite of Kolmanab Hill 305

36. Diabase from under the Nubian sandstone, Rod el Nagi 306

37. Diabase from Gebel Abu Hamamid 308

38. Olivine-diabase from a dyke at the junction of Wadis Gemal and Huluz 308

39. Diabase from a dyke in Wadi Kreiga 309

40. Mica-diabase of Gebel Um Khariga 310

41. Basalt of Gimeida Hill 311

42. Basalt of Einiwai Hill 312

43. Amphibolite from hills near Gebel Um Gunud 317

44. Amphibolite containing olivine and bronzite, Qrein Salama 319

45. Serpentine (probably from a mica-peridotite), east of Erf el Fahid 321

46. Serpentine (from lherzolite), hills near Wadi Um Khariga 322

47. Serpentine (from dunite), low hills near Bir Abraq 326

48. Serpentine (from dunite), low hills near Bir Abraq 326

49. Serpentine (from wehrlite), Gebel Gerf 327

50. Bronzite passing into serpentine, Gebel Gerf 327

51. Serpentine (from harzburgite,), Gebel Korabkansi 329

52. Crushing of quartz and felspar in granite-gneiss, Gebel Um Rasein 334

53. Diorite-gneiss, Wadi Muelih 334

54. Crushed and altered syenite (schist), near Gebel el Anbat 339

55. Hornblende schist, Wadi Muelih 340

56. Schist composed of crushed volcanic rocks, Gebel Abu Hamamid 341

57. Hornblende schist, near Gebel Eqrun 343

58. Emerald and quartz, near Sikait 345

59. Tourmaline in talc-schist, Sikait 346

60. Section of sandstone at Gebel Um Khafur 358

61. Junction of sandstone and granite, west of Gebel Um Reit 359

62. Faulting near Wadi Saalek 359

* * * * *

=THE GEOGRAPHY AND GEOLOGY OF SOUTH-EASTERN EGYPT.= * * * * *

CHAPTER I.. * * * * *

* * * * * =INTRODUCTION.= * * * * *

The district treated of in this volume constitutes the extreme south-east corner of Egypt, lying between the parallels of 22° and 25° of north latitude, and between the meridian of 34° E. and the Red Sea coast. It comprises an area of about 56,000 square kilometres, and includes some of the most mountainous and least accessible portions of the Khedive’s dominions.

The district has been comparatively little visited by travellers, and the literature concerning it is not very extensive. Berenice (Jh) was founded by Ptolemy II (285-247 B.C.), who named the town after his mother, as a station at one end of the road for transporting goods from the Red Sea to the Nile at Koptos (Quft). The emerald mines in the Zabara area were worked at least as early as Ptolemaic times, and gold mines in the south at a much earlier date.

References to this part of Egypt occur in the writings of STRABO, DIODORUS SICULUS, and PLINY, as well as in PTOLEMY’s Geography and the ANTONINE ITINERARY. Both Strabo and Pliny state that in Berenice, as in Syene, the sun cast no shadow at the summer solstice from which they inferred the town to be on the tropic of Cancer, though in reality it lay in their day some twenty-five kilometres, and is now about 28′, or some fifty-two kilometres, north of the tropic, the difference being caused by the secular change in the obliquity of the ecliptic since the beginning of the Christian era. Ptolemy gives the latitude of Berenice as 23° 50′, which is only 5′ too low; the Smaragdus mons, or emerald mountain, he places in latitude 25°, which is about 15′ higher than the true position of Gebel Zabara (Ec). Diodorus gives a very clear description of the working of gold mines in the Eastern Desert in his day, by miserable convict labour. The road from Koptos to Berenice is mentioned, with lists of stations and water reservoirs and their distances from each other, both by Pliny and the writer of the Antonine Itinerary; and though Pliny gives fewer stations than the Itinerary, the two accounts agree very closely in estimating the total distance at about 258 Roman miles, which, so far as can be judged from a partial identification of the stations marking the route, is pretty correct. The island of Zeberged (Ok), on which occurs the green gem called peridot, is probably the Topazos Insula of Diodorus, and the Agathon of Ptolemy; but Diodorus gives its length as eighty stades (about twelve kilometres), which is three times greater than its present size, and Ptolemy’s latitude of 23½° is some 16′ too low. Ptolemy states that the coast was inhabited by the Ichthyophages, or fish-eaters, while the Troglodytes, or cave-dwellers, of Strabo, were probably the workers in the mines.

The books of the Arab geographers, EDRISI and ABU EL FEDA, contain some references to the roads and mines of the Eastern Desert, but their descriptions are unimportant and contain frequent palpable errors.

D’ANVILLE, in his Mémoires sur l’Egypte, Paris, 1766, pp. 230-235, attempted to construct a map of the coast of the Red Sea by combining the classical records with some early Portuguese and other charts, but the latter were too crude to enable any approach to be made to an accurate map.

It has been thought that BRUCE discovered the island of Zeberged and the emerald mines of Zabara in 1769, but it is tolerably certain that he saw neither of these places. He estimated the latitude of the island he saw “pretty exactly” as 25° 3′, and its distance from the coast as three miles, whereas Zeberged is really in latitude 23° 36′, and is over thirty miles from the nearest coast. The mines he saw were so close to the coast that he could walk to them from his boat and back in less than a day (in fact he states that they were only three miles from the coast), while both the Sikait and the Zabara mines are over a day’s journey from the sea. Nor could the mines have been the sulphur workings near El Ranga (He), unless Bruce made a large error in his observation for latitude, for the sulphur mines are about in latitude 24° 25′, and, moreover, Bruce states that he found “brittle green crystals,” not sulphur.

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