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 enclosing within Afghanistan the only approach to Seistan from India which is available during the seasons of Helmund overflow. Between Afghanistan and Persia the boundary was defined by Sir F. Goldsmid’s Commission in 1872 from the Malik-Siah-Koh to the Helmund Lagoons, and rectified by the Commission under Sir Henry MacMahon in 1903–1905. Beyond these lagoons to Hashtadan it is still indefinite. The eastern limits of Hashtadan had been previously fixed as far north as the Hari Rud river at Toman Agha. From this point to Zulfikar the Hari Rud is itself the boundary.

Within the limits of this boundary Afghanistan comprises four main provinces, Northern Afghanistan or Kabul, Southern Afghanistan or Kandahar, Herat and Afghan Turkestan, together with the minor dependencies of the Ghilzai and Hazara Highlands, Ghazni, Jalalabad and Kafiristan. All these are described in separate articles. The kingdom of Kabul is the historic Afghanistan; the link which unites it to Kandahar, Herat and the other outlying provinces having been frequently broken and again restored by amirs of sufficient strength and capability. The Herat province is largely Persian, while Afghan Turkestan is chiefly Usbeg; and in neither is the sentiment of loyalty to the central government very strong. The bond is geographical and political rather than racial. The geographical divisions of the country are created by the basins of its chief rivers, the Kabul, the Helmund, the Hari Rud and the Oxus. The Kabul river drains Northern Afghanistan, the Hari Rud the province of Herat, and the Oxus that of Afghan Turkestan. Afghanistan is largely a country of mountains and deserts; but there are wide tracts of highly irrigated and most productive country where fruit is grown in such abundance as to become an important item in the export trade. The Afghans are expert agriculturists and make profitable use of all the natural sources of water-supply. As practical irrigation engineers they are only rivalled by the Chinese.

The dominant mountain system of Afghanistan is the Hindu Kush, and that extension westwards of its water-divide which is indicated by the Koh-i-Baba to the north-west of Kabul, and by the Firozkhoi plateau (Karjistan), which merges still farther to the west by gentle gradients into the Paropamisus, and which may be traced across the Hari Rud to Mashad.

So far as we know at present the geological history of Afghanistan differs widely from that of India. When, somewhere at the commencement of the Cretaceous period, the peninsula of India was connected by land with Madagascar and Southern Africa, all Afghanistan, Baluchistan and Persia formed part of an area which was not continuously below sea-level, but exhibited alternations of land and sea. The end of the Cretaceous period saw the beginning of a series of great earth movements ushered in by volcanic eruptions on a scale such as the earth has never since witnessed, which resulted in the upheaval of the Himalayas by a process of crushing and folding of the sedimentary rocks till marine fossils were forced to an altitude of 20,000 ft. above the sea. It was not till the Tertiary age, and even late in that age, that much of the land area of Afghanistan was raised above the sea-level. Then the ocean gradually retired into the great Central Asian depressions.

Everywhere there have been great and constant changes of level since that period, and the process of flexure and the formation of anticlinals traversing the northern districts of Afghanistan is a process which is still in action. So rapid has been the land elevation of Central Afghanistan that the erosive action of rivers has not been able to keep pace with that of upheaval; and the result all through Afghanistan (but specially marked in the great central highlands between Kabul and Herat) is the formation of those immensely deep gorges and defiles which are locally known as daras. One of these, in the Astarab, to the south-east of Maimana, is but 30 yds. wide, and is enclosed between perpendicular limestone cliffs 1500 ft. high. C. L. Griesbach considers that the general outline of the land configuration has remained much the same since Pliocene times, and that the force which brought about the wrinkling of the older deposits still continues to add fold on fold. The highlands which shut off the Turkestan provinces from Southern Afghanistan have afforded the best opportunities for geological investigation, and as might be expected from their geographical position, the general result of the examination of exposed sections leads to the identification of geological affinity with Himalayan, Indian and Persian regions. The general configuration of the Turkestan highlands has been already indicated.

Against the last great fold which terminates this mountain area northwards are ranged the Tertiaries and recent deposits. North of Maimana they form low undulating loess hills, in which most of the Band-i-Turkestan drainage is lost. This wide-spreading loess area, formed partly of wind-blown sand and partly of detritus from the mountains, is known as Chul, and merges into the great plains south of the Oxus river, a great part of which is covered with modern aerial deposits. Beneath this Chul formation the older beds of the outer and Turkestan ranges dip and pass to an irregular outcrop near the banks of the Oxus. Between the Oxus and the hills there has already been formed a rise or flexure in the ground, which extends more or less parallel to the northern edge of the hills, and, shutting in the cultivated area of the plains, arrests all tributaries seeking to effect a junction with the Oxus from the south, and leads to the formation of marshes and swamps. This appears to be the beginning of a new anticlinal which has altered the levels of the Balkh plain, and is indicative of those elevating processes which