Chapter I: Physical Geography (2)

The province of Zaria lies almost entirely within the drainage basin of the Kaduna river, only a narrow belt of country in the south and south- west being drained by the rivers Gurara and Bako. With the exception of the uppermost springs of the Kaduna and the lower navigable portion of its valley below Wushishi, the whole course of the river is included within the province. At Wushishi the river narrows and its channel becomes much obstructed by rocks and rapids, as it winds through the belt of hills which separate the rocky plains of western Zaria from the lower plains of Nupe. At Zungeru the Kaduna flows in the dry season in a narrow picturesque gorge between white walls of quartzite, which in the rains are buried under a rushing foaming torrent. (Plate VIII, Fig. 2.) From the bend of the river above Girku in the east of the province, the Kaduna flows south-westward over stretches of drift-covered plain and through scattered groups of hills with its channel marked by frequent rocks and rapids, while beyond Girku the river meanders peacefully over the lofty plains which stretch eastward to the boundary of the province. The larger tributaries of the Kaduna on the north bank, the Kara, Koriga, Tubo, and Shika, take their rise upon the high plains of Hausaland, along whose crest runs the primary watershed between the systems of the Niger and Lake Chad, and, like the Kaduna itself, they flow in their middle and lower courses over broken plains and between groups of hills which separate the minor streams. The Leri river in the east rises on the high plains of the Bauchi border, while the Dunia and Serakin Pawa, the principal tributaries on the left bank, as well as the headwaters of the Gurara, take their rise amidst the scattered hills upon the lofty plains of the south-east. The Bako river rises in the hilly ground around Fuka and, with the Gurara, drains the extreme southern portion of the province.

The hills in Zaria province are of two types; (1) ranges or belts of low rounded and somewhat broken hills, composed largely of the more resistant schists, or of a mixture of granite and schist; (2) kopjes, inselberge and small detached groups of rounded granite hills, with here and there an extensive elongated mass of granite with a more or less flattened tabular summit and steep though worn and rounded slopes rising abruptly from the plains which encircle its base. To the first type belong the tract of hilly country in the west of the province which stretches from Mikonkeli to the south of the Kaduna as far as Kagara to the north, the belt of hills between Gwari and Koriga in the north of the province, the broken stony country around Fuka in the south, and the line of hills in the centre of the province from Dorka to Kaserimi. To the second type belong the solitary turtlebacks and detached masses of granite hills which so abundantly diversify the plains, while the Kudaru, Ruruma, and Kerko hills are somewhat worn examples of the steep- sided granite massifs, whose flattened though hummocky summits form the retreat of numerous pagan tribes.

Over the greater part of the province the configuration of the surface presents a very close resemblance to the characteristic scenery of the plains of Kabba (p. 17). Between and around the island mountains and groups of hills and tracts of hilly country, spread undulating thinly- wooded drift-covered plains. The towns and villages are set picturesquely on the slopes and summits of the hills or in patches of thick forest in the midst of the plain. For long distances round the bases of the hills the plains are cleared and cultivated, and from the summit of any of the isolated mounts the peculiar character of the landscape impresses itself, as before, upon the observer. Here and there the solitary hills raise their rounded crests in lonely grandeur, while around and between them the rivers pick their sluggish course over the monotonous plain. The lofty drift-covered levels of the south-east are largely uninhabited and cultivated only by the pagans who daily descend from their rocky strongholds in the Ruruma Hills or on the margin of the Bauchi plateau. Only in the north-east between Girku, Leri, and Zaria do the plains assume the typical aspect of Hausaland (p. 21). The gently undulating surface is deeply buried in sandy drift, and in places floored with surface ironstone: extensive stretches of the grassy plains become swampland in the rains: the landscape is diversified only at long intervals by occasional turtlebacks and groups of granite hills, while well-walled towns and villages are set here and there upon the open plains or built round the bases of the solitary hills themselves, which serve as watch-towers in times of danger.

The major part of the province of Zaria may be conceived as a shallow, elongated basin, draining westward, and shut in on the north and north- east by the high plains of Hausaland and on the south-east by the Amo, Piti, and Chawai hills, the lofty plains of Katab, and the tableland of Nassarawa. The greater part of Bauchi province, on the other hand, may be looked upon as an undulating plain sloping gently towards the north- east. The south-western portion of the province is occupied by the great plateau of Bauchi, which is limited on the north and south by well- defined walls of rock. (Map p. 40). The plateau, however, is not a true tableland in the sense of an elevated plain marked off on all sides by precipitous walls from the lower plains around. Like the tablelands of Kabba, Nassarawa, and Southern Yola, which are at most inclined plains bounded by escarpments on one side only, the Bauchi plateau from its summit at Bukuru slopes gently eastward and merges gradually into the plains of the Gongola, while on the west between the northern and southern escarpments it is continuous for a short distance between Kwoll and Assab with the highest portion of the tableland of Nassarawa. The intimate relation which exists between the Bauchi plateau and the tableland of Nassarawa is further demonstrated by the continuation of the escarpment of the tableland beyond Assab to form the southern wall of the plateau. From Assab the escarpment, here 1,500 to 2,000 feet in height, runs south-eastward to the neighbourhood of the ninth parallel before swinging round to the north-east and losing itself amongst the rocks of Angass, where the single escarpment appears to be replaced by a succession of rocky steps leading down to the tract of broken country between Angass and Kanna, which is drained by the headwaters of the Wase river.

The northern margin of the plateau is more irregular than the southern and marked by projecting spurs which have now assumed the character of mountain ranges. In the west the escarpment begins in the neighbourhood of Kwoll and Miango and stretches westward as a somewhat worn and rounded cliff, 1,000 feet in height, separating the lofty plains of Rukuba from the lower plains of Zaria. Beyond Chawai and Piti the escarpment is continued as the western slope of the Amo, Jengre, and Gura hills, which run out upon the broken plains to the north, while the eastern slope of the hills again assumes the character of an escarpment and bounds the valley of the Delimi as far as the gorge of the river below Naraguta. To the east of the Delimi, however, the single escarpment is replaced by at least two steps which interpose the broken plains of Toro and the summits of the Kwandokaya hills between the plateau and the northern plains, while to the south-east of Polchi the escarpments run out upon the plains of the upper Gongola in groups of picturesquely rounded hills. There is some reason also to believe that the plateau is stepped or broken in the neighbourhood of Basak in the Rukuba country, but this point must await further investigation.

The surface of the plateau reaches its highest elevation of about 4,100 feet in the neighbourhood of Ngell and Bukuru, whence the headwaters of the Delimi, Sungo, Gongola, and Kaduna radiate approximately north, south, east, and west. Of these rivers the Delimi ultimately joins the Yo and falls into Lake Chad, the Gongola and Sungo join the Benue, and the Kaduna the Niger. Thus the few square miles in the neighbourhood of Ngell and Bukuru may rightly be claimed as the hydrographical centre of the Protectorate (p. 3), and even the most casual observer cannot fail to be impressed here with that peculiar character of the primary watershed which has already been remarked in the case of the western tributaries of the Niger and the northern tributaries of the Kaduna. There is no group of rocky mountains, no rugged peak at the hydrographical centre of the Protectorate, no lofty ranges forming the watersheds between the radiating rivers: only an undulating, swampy, alluvial plain, diversified by a few short, broken ridges and low kopjes of granite boulders. Into these plains, however, the rivers which flow north, west, and south are rapidly carving narrow rocky valleys, and their descent to the lower plains is marked in every case by picturesque waterfalls and narrow gorges cut back for considerable distances into the plateau itself. The wooded gorge of the Delimi below Naraguta, the steep waterfalls of the Kaduna between Kwoll and Miango, and the deep rocky channel of the Kogin Rim above Assab afford striking evidence of the activity of the rivers. Only in the east where the plateau inclines gently towards the Gongola do the streams flow in sandy beds between deep banks of alluvium, with broad stretches of swamp on either bank wherever the slope is insufficient to drain the summer floods.

MAP No. 2.

London. Macmillan & Co., Ltd.

_Face p._ 40.]

The Bauchi plateau, in the more restricted sense, may be taken to include all those portions of the elevated plains which rise above 3,500 feet. Upon this definition the plateau is bounded on the south by the continuous escarpment which stretches from Sura to Assab, and on the west by a line drawn northward from Assab to Kwoll and Miango. Beyond Miango the plateau is again limited by an escarpment as far as the Jengre Hills, whence the boundary runs southward to Naraguta and thence eastward along the higher escarpment behind Toro. The eastern boundary of the plateau is formed by a line drawn approximately from south to north from Kereng to Toro. The most striking feature of the greater part of the plateau as thus defined, with the exception of the Rukuba country to the north, is the bare and treeless aspect of the surface, which assumes the character of undulating grassy downs extensively cultivated in the neighbourhood of the towns and villages (Plate IX, Figs. 1, 2). Only amidst the clusters of rocky hills which diversify the surface do a few wind-worn trees bear witness to the former extent of the forest, while round the bases of the hills and among the boulders on their slopes are set the rectangular compounds of the pagan villages, whose dark green hedges of prickly cactus add a pleasing touch of colour to the mellow landscape. The low hills which rise from the plateau have also a peculiarity all their own, which is to be directly correlated with the greater diurnal variation in temperature. The turtlebacks and domes and rounded hills of the lower plains are here conspicuously absent, and in their place appear heaps of boulders and jagged ridges of granite, with picturesque peaks and pinnacles and perched blocks adorning their crests. Here and there, also, in the Rukuba and Kibyen country in the west and in Sura in the south-east, more or less worn and rounded volcanic cones rise above the general level of the plateau (Plate X, Fig. 1). The craters of Kereng (Plate X, Fig. 2) in the south- east, however, are remarkably well preserved. The surface of the plateau itself is, moreover, deeply covered with drifted alluvium and provided in places with a crust of surface ironstone through which the rivers and streams have in many cases cut to the rock below. Above Assab the drift has been largely removed from the surface, and between Rim and Woran numerous grassy, flat-topped hills of red, gritty earth, capped by a hard ferruginous crust, rise in places to a height of at least 300 feet above the level of the plateau margin. These hillocks recall in appearance the tabular sandstone hills of the Niger valley, and bear striking witness to the former extent and thickness of the superficial accumulations (Plate XI, Fig. 1). The broken, rocky character of the marginal belt of plateau on the north in the neighbourhood of Zammagan, Basak and Naraguta is probably also largely due to the removal of the covering of drift which formerly obscured many of the irregularities of the surface. Isolated hillocks of drift indeed are common throughout Rukuba to the west of Jos and Naraguta (Plate XI, Fig. 2), while at Basak they may be seen capping the very summit of the cliffs.

Beyond the limits of the plateau proper, a thinly wooded drift-covered plain, in places somewhat broken and hummocky and diversified in the usual manner by inselberge and scattered groups of granite hills and drained by the headwaters of the Gongola, stretches eastward to the meridian of Bauchi. Similarly, beyond the worn and rounded escarpments and projecting spurs which form the northern margin of the plateau, an undulating wooded plain, drained by the Delimi and its tributaries, extends north-eastward towards the Kano border. The western watershed of the Delimi valley runs along the hummocky drift-covered plain which stretches northward between the Gura hills and the detached mass of the Liruei-Kano hills, and thence through the rocky hilly country round Tirkunya into the Ningi hills, which form the most striking feature of the north-western portion of the province. This elongated mass of hills, which stretches from Bura in the west to Ari in the east, is a typical instance of those steep-sided and more or less tabular granite massifs, of which examples have already been noted in the Ruruma hills of Zaria, the Kagoro hills of Nassarawa and the Vere hills of Yola. The Ningi massif reaches a higher elevation in the west than in the east, its slopes are much rounded and incised by narrow valleys, its summit is broken and hummocky with a scanty soil of disintegrated granite, while wooded drift-covered plains stretch outward from its base towards Zaria on the west, towards Kano and Katagum on the north, and towards the Delimi valley on the east and south.

The surface of these wooded plains rises gently in the north to form the low watershed between the valleys of the Delimi and the Shidya. The headwaters of the Shidya rise in the tract of broken hilly country which lies to the north and north-east of Bauchi, and forms in part the northern watershed of the Gongola basin. Around Bauchi itself domes and turtlebacks and groups of rounded hills, rising from the stony and drift-covered plains, are particularly numerous and often remarkably picturesque in their outlines, the lion couchant being one of the commonest forms which the bare granite hills assume. (Plate XII, Figs. 1 and 2.) South of the Gongola the plains slope gently upward to the base of the Jarawa and Kanna hills, becoming more and more broken and stony as they approach the watershed of the Wase river. The granite massif of the Wadai hills between Angass and Sura is only known along the northern margin, while Angass[13] itself is a particularly broken and rugged district separated from the Murchison Range by a series of rocky valleys still largely unexplored. Between Angass and Kanna the high drift- covered plains of Bauchi pass into a tract of broken country which is drained by the headwaters of the Wase river and falls rapidly to the plains of Yergum.[14] The line of fracture to the west which forms the margin of the plateau appears to be replaced here by a simple flexure or perhaps by a succession of worn and broken steps. Farther east rise the Kanna and Kantana hills, with their projecting spur towards Kwankyam, whose steep though worn escarpments interpose an ascent of 700 to 1,000 feet between the lower and higher plains. The western hills, which are prolonged northward into the Jarawa country, are composed of crystalline rocks, and the more prominent peaks possess the usual rounded outlines of granite hills. The Kantana hills to the east, however, are sedimentary in origin, and from a distance show the familiar tabular outlines of horizontal sandstone hills, the narrow plateau on top being, however, much eroded and incised. Eastward the escarpment appears to be much stepped, and in the neighbourhood of Tukkur wheels northward to form the eastern slope of the Jarawa hills which run out upon the plain of the Gongola.

The eastern portion of the province is almost entirely covered with sedimentary rocks. In the centre, a little to the south of the parallel of Bauchi, broad plains stretch eastward from Goram and Lafiangale to Deba Habe and the Gongola, bounded on the north by the broken sandstone plateaux which are enclosed within the bend of the Gongola, and on the south by the slopes of the Kudu valley, the rounded hills of Gateri and the picturesque peaks of Tangale. In the west the plains are deeply covered with sandy drift, through which the headwaters of the Kudu have cut narrow canyon valleys into the sandstones below. Farther east the summer rains render the plains for long distances almost impassable swamps which drain imperceptibly east or west, and leave in the dry season a gently undulating surface of black, gritty clay, baked and fissured by the summer sun. To the north of the central plain and within the bend of the Gongola lies a region of detached tabular masses of elongated or irregular outline, together with groups of worn and rounded sandstone hills, separated by stretches of sandy plain, presenting all the familiar scenic features of the dissected sandstone plateaux of the Niger. The narrow valley of the Gongola, between Deu and Gombe, bounded by flat-topped ranges on either side, presents a marked contrast in scenery to the upper course of the river above Baddera, where it threads its way over the high plains of Bauchi between turtlebacks and domes of granite. Below Gombe, however, the valley opens out and the river flows as far as Nafada through an open sandy plain, diversified by occasional flat-topped sandstone hills. Between Nafada and Ashaka the channel winds between detached hills and short tabular ranges which rise from an undulating, thinly-wooded plain, while below Ashaka the river enters the deeply drift-covered plain which stretches from the base of the Tilde and Dukul hills on the west to the foot of the escarpment of the Barbur plateau in Bornu on the east. As far as Jurara and Deba Filani the plain is thickly populated, well-cleared and cultivated; southward, however, within the Habe country, the scattered villages are separated by longer stretches of bush, while the plain is diversified by hummocks of sandstone and worn hillocks of basalt with the intervening irregularities of the surface deeply buried in drift. Beyond Deba Habe, the plain of the Gongola forms the eastward continuation of the central plain of Bauchi, whose sandy and swampy surface stretches southward to the base of the Tangale hills.

The south-eastern portion of the province is occupied in part by the upper valley of the Kudu river and in part by the extensive mass of hills which, with the exception of the outer margin around Gateri, Tangale, and Waja, is still largely unentered and unexplored. A series of narrow valleys, terminated by canyon-like gorges, have been cut by the headwaters of the Kudu into the elevated plains of Pali and Lafiangale. The difference in level between the upper plains and the river bed is greatest in Dugari in the west, where the streams flow in narrow flat-bottomed valleys, bounded by perpendicular walls of white sandstone three to five hundred feet in height. From the cliffs above Tongolan the scenery recalls in miniature the chasms, amphitheatres, and canyons of Colorado, with their promontories and projecting buttresses, steep slopes and vertical ledges, while south-eastward towards Yuli the remnants of a lower plateau mark a former pause in the activity of the river. Farther east, by Panguru and Putu, the relative height of the upper plains decreases, the sandstones become broken and inclined, and the tributary valleys are bounded, not by cliffs, but by rounded, drift- covered slopes leading upward to the higher undulating plains. The folded sandstones of Gateri and Ligri give rise to a group of rounded hills deeply incised by narrow valleys and backed by the ridges and peaks of the unexplored Wurkum and Pero hills, which stretch north- eastward towards the Gongola. From Gateri northward to Putu the track leads over somewhat broken country, while eastward from Putu to Tangalto stretch open, undulating, swampy plains, diversified only by occasional conical stumps of basalt.

PLATE IV

The tract of country which lies between Tangale and the Gongola is one of the most picturesque within the Protectorate. The hills rise in detached groups from an irregular hummocky plain, and form the advanced guard of the belt of lofty highlands which intervene between the northern plains and the Benue. While the whole district may be spoken of generally as Tangale, the Tangale tribe itself occupies a very restricted area and is lodged within only the westernmost group of hills, the successive groups to the east and south being inhabited by the kindred but mutually hostile tribes of Chongwom, Ture, Awok, Tula, and Waja. Tangalto and Tall, the strongholds of the Tangale tribe, are set on the slopes of rounded granite hills, picturesquely pierced by worn pillars of trachyte and basalt, and separated by a narrow undulating plain from the neighbouring group of granite hills inhabited by the pagans of Chongwom and Kaltungo. Beyond Chongwom the character of the scenery entirely changes. In place of the rounded crystalline hills there rise precipitous and more or less tabular masses of well-bedded sedimentary rock, forming natural fortresses in the midst of an undulating park-like plain, diversified by knobs and hummocks and standing rocks of sandstone (Plate XIII, Fig. 1). At times the summit ridges are gently curved and the hills are bounded on one side by a steep escarpment and on the other by a dip slope sinking gradually to the plains below, while the whole landscape is dominated by the Ture or Tangale Peak, a picturesque pillar of trachyte rising from a worn and flattened basal cone of sandstone (Plate XIII, Fig. 2). Eastward, around Jelengu and Reme, somewhat similar pillars of volcanic rock project here and there above the sandstone hills, while the worn escarpments of Waja appear to be continuous with those which form the western boundary of the lower Gongola valley. The country which lies to the south of Tangale and Waja is quite unknown. From the upper slopes of the Ture Peak, a second distant range of hills can be seen running parallel with the jagged ridge in the foreground, and it is probable that, instead of a mass of hills or a continuous plateau, there is within this unexplored land a succession of broken valleys and rocky ridges, forming one of the last strongholds of paganism within the Protectorate.

_The Northern Provinces.—Bornu, Kano, and Sokoto._

The southern portion of Bornu, which lies immediately east of the Gongola, presents, so far as the character of its physical features is concerned, a greater affinity with the central provinces of Bauchi and Zaria than with the northern Hausa States or with the northern portion of Bornu itself. The valley of the Gongola to the east of the river is more broken and hummocky than it is to the west. The sandstones are much faulted and variously inclined and form belts of rocky plain between the swampy valleys of the tributary streams. Here and there, as at Wuyo and Gulani, a circle of jagged ridges forms a natural battlement round a pagan town, or, as at Balbea, a flattened sandstone hill forms a natural stronghold in the midst of the plain. More striking, however, are the level crests, the dip slopes and the steep escarpments of the Bima and Wadi hills, which form the landmarks of the Gongola plain from Ashaka to Wuyo. From Gulani north-westward to Ashaka stretches an extensive undulating plain, broken only by an occasional ridge of sandstone, with black swamp earth covering all the minor irregularities of the surface and creeping up the slopes of the sandstone hills themselves. Eastward the broken plain of the Gongola is bounded by the worn escarpment of the Barbur volcanic plateau which becomes higher towards the north, and between Bilaraba and Dukshi is fringed with a series of flat-topped and conical outliers of basalt. To the east of Gulani and Balbea the ascent to the plateau is over basal sandstones capped by black volcanic rock. Farther north, however, in the neighbourhood of Dukshi, the escarpment is entirely composed of basalt and rises from an irregular crystalline floor. The summit of the plateau is broken and rocky in the west, deeply trenched by the tributary streams of the Gongola, and diversified by numerous worn and rounded cones of ash and lava. Eastward towards Buratai the plateau descends by a series of low rocky steps separated by drift-covered levels to the plains of Hong and Ajigin, whose deep covering of dark gritty clay, hard and fissured in the dry season, forms an almost impassable swamp in the rains. In the south-east, towards Biu and the little-known Burra country, the volcanic cones become higher and more conspicuous, while the surface of the plateau, according to native information, becomes much dissected and broken up into narrow plains and rocky valleys.

Two tracts of hilly country, separated by the swamps of Hong and Ajigin, lie respectively to the north-west and north-east of the volcanic plateau. The worn and flattened hills of sandstone and ironstone, which stretch westward from Buni and Ligdar towards Gabai, pass northward into the high, drift-covered plains of Mutwe and Gujba, which form the watershed between the Gongola and Lake Chad. In the east the Tagum and other groups of flat-topped hills around Lua, Ndufa, and Korode represent the remains of a sandstone plateau once continuous with the hills of Buni and Ligdar across the swamps of Ajigin. To the north and north-east of the Tagum hills stretch the great wooded plains of Bornu, with their gently undulating surface sloping imperceptibly towards Lake Chad, and with not a single hill nor even a hummock of boulders to relieve the monotony of the scenery. To the south-east of the Tagum hills the sandstones run out upon a crystalline floor which stretches southward into Yola province, with its surface diversified only at long intervals by island mountains and groups of granite hills.

The plains of Bornu, which stretch northward from the rocks of Chibuk and the Tagum hills to Lake Chad and the river Yo, are in the east so imperfectly drained that extensive tracts of their surface become marshy and swampy during the rainy season. The swamps reach their greatest development in the valley of the Yedseram and in the immediate neighbourhood of Chad, where the whole country is flooded after the rains. Barth[15] has described in a sufficiently vivid manner the featureless and cheerless aspect of the swampy plains to the south and south-east of Chad. Along the caravan road from Maidugari to Kukawa transverse stretches of swamp land (firki) alternate with belts of slightly higher ground, hard and smooth on the surface, or thinly coated with loose yellow sand or dark grey loam. The character of the vegetation reflects immediately the changes in the nature of the surface soil. In the dry season, after the grass is burnt, the cracked and fissured surface of the firki land is absolutely bare and treeless, the hard and smooth surfaces of sandy clay are covered with thin mimosa bush, while the stretches of loose sandy loam support a more abundant growth of trees and scrub. The ancient dunes and the undulating sandy plains which bound the northern basin of Chad support an open forest growth, while recent accumulations of blown sand are now found only within the towns themselves, or in places which have been cleared of forest for purposes of cultivation.

The Maidugari river, which rises on the Yola border and loses itself in swamp a few miles to the north of Maidugari, has cut deeply into the superficial sandy drift in the neighbourhood of Maidugari and Maifoni and formed a comparatively narrow valley with steeply-rounded slopes. From Maifoni a gently rolling plain stretches westward to Gujba, with occasional thick-stemmed kukas rising prominently above the low growth of scrubby trees and prickly mimosa which covers the surface, and with here and there a dry “tubka” or shallow swampy hollow forming an open space within the forest. At Murguba, and again at Gujba, the plain is broken by shallow water-courses, bounded by low and ill-defined ridges of rising ground. These extended swampy hollows are flooded during the rains, and in the dry season marked by a line of wells and occasional pools separated by sandy bars. Beyond Gujba the rolling plains become again marked by a rapid alternation of sandy rising ground and clayey shallows draining southward in the rains. Between Chumga and Abakri, however, rock begins to appear in places on the surface of the drift- covered undulations which separate the swampy valleys, while a few isolated flat-topped or rounded hills are scattered over the plains. From Abakri can be seen to the west the long flattened and rounded ridges and tabular hills, half buried in sandy drift, which introduce the Kerri Kerri plateau. Daura and Durua are set within this broken country, each at the base of a low flat-topped range of ironstone hills, while the track leads over a succession of stony ridges and shallow cultivated valleys to the continuous plateau surface which is reached about half-way between Durua and Momdo. The plateau itself is no higher than the summits of the marginal hills, which with their drift-filled valleys represent merely the dissected eastern front of the tableland. The surface of the plateau, at first thinly wooded and in places somewhat stony, passes westward into the open sandy undulating plains around Potiskum, which fall away gently to the north and west into the valley of the Kogin Shidya. Here and there a low hill or a rounded ridge of sandstone or ironstone rises above the general level, with the sandy drift which obscures all the minor irregularities of the surface deeply banked against its slopes.

The Kerri Kerri plateau, like the tableland of Nassarawa and the elevated plains of Bauchi, is not a true plateau in the strict sense of the term, but rather an inclined plane, bounded by more or less worn escarpments on the south and passing gradually northward into the plains of Ngizem. The escarpments which stretch from the neighbourhood of Daura south-westward to the provincial boundary reach their greatest elevation behind Dozi, Lewe, and Gamari to the north-west of Nafada, where precipitous cliffs of white sandstone 500 to 600 feet high rise abruptly from the sandy plains which stretch southward to the Gongola. The escarpment, however, is in no sense a continuous one, for, as already noted in the neighbourhood of Daura, the margin of the plateau has been much cut up and dissected, especially in the east, into a system of more or less detached flat-topped ranges and tabular masses separated by narrow valleys or by short stretches of open plain.

Westward where the escarpment is higher, as in the neighbourhood of Dozi and Kadi, the cliffs are furnished with the characteristic buttresses and indentations of horizontal sandstone rocks, while the margin of the plateau is fringed with a series of detached tabular and conical outliers of varying size and elevation (Plate XIV, Fig. 1), the larger of which form natural strongholds for pagan villages.[16] The most remarkable feature, however, about the margin of the plateau is that, behind the fringing belt of detached ranges and outlying groups of hills, the main mass of the plateau has been grooved or incised by a series of narrow flat-bottomed trench-like valleys, bounded by perpendicular walls of white sandstone and notched and indented by lateral gullies (Plate XIV, Fig. 2). For long distances the narrow valleys preserve a very constant breadth, while frequently they turn abruptly at right angles or are joined by lateral valleys of similar character which unite the whole series into an interlacing system through which it is possible to travel from Daura to Zai without once ascending to the level of the plateau above. At their upper ends the valleys rapidly contract and run out upon the plateau as steep and rocky gullies. Their floors, like the surface of the plateau above, are well cleared for cultivation and studded with scattered trees, while the villages are set aloft on the margin of the cliffs overlooking the wells in the valley below.

Beyond the western boundary of Bornu the escarpments die down, and the drift-covered surface of the plateau falls gently to the swampy valley of the Kogin Shidya. The last trace of the sandstones of Kerri Kerri is found in the low hills of conglomerate and grit around Hardawa, while twenty miles to the north according to native information the sandstones disappear in the neighbourhood of Lise under the sands and swamps of Katagum. Beyond Hardawa begin the undulating plains of Hausaland (pp. 21, 38), which stretch westward, to the north of the Ningi massif, through the heart of Kano and the north-eastern portion of Zaria into Kontagora and Sokoto. Here and there a heap of granite boulders or an isolated group of rounded hills, as at Shira, Fagam and Kila, rise out of the red sandy drift which is deeply banked against their slopes, and which elsewhere effectually buries the irregularities of the crystalline floor. Occasionally a smooth and rounded surface of gneiss or granite outcrops level with the plain, while the rivers which flow in broad, shallow and ill-defined valleys, indistinguishable at a distance from the rest of the plain, have here and there succeeded in cutting their channels through the sandy drift to the solid rock below. Where uncultivated the plains are covered with prickly mimosa bush, or with trees well spaced or in bushy clumps with open grass around. The farm- land, however, is well cleared and comparatively bare with a few large trees scattered here and there amongst the furrows, while the fallow is thickly covered with tall aromatic grass and low scrubby trees of a few seasons’ growth.

From Jemaari north-eastward to Katagum, and thence westward to the immediate neighbourhood of Kano, not a single rock is anywhere exposed, and not a single block or boulder or even a pebble of quartz is to be found in the sandy loam which covers the surface. North of Jemaari the track leads through gently undulating country presenting the usual alternations of farm-land and thinly wooded plain. Between Itas and Murmur the surface becomes in places quite hummocky with ancient dunes in the form of low rounded ridges of loose sandy drift, extended approximately east and west, rising in succession upon the level plain and bearing witness to the former prevalence of desert conditions. Around Katagum the drainage is so imperfect that long stretches of the plain are under water in the rains, while westward beyond Kwotolu the surface resumes its undulating aspect with its alternation of sandy rising ground and clayey shallows. Here and there, as at Koya, a rounded ridge of loose sand, now covered with grass and scattered trees, affords evidence of the former activity of the wind, while in places in the hollows are small sheets of fresh water forming lakes which are more or less permanent throughout the year.

Around Kano and north-westward towards Katsina the open undulating plain presents all the characteristic features of a crystalline floor. For long distances round the towns the red sandy loam which covers the surface has been cleared of all but the larger trees and subjected for generations to intense cultivation. Here and there around Kano smooth surfaces of rock appear level with the plain, or rise into low rounded turtlebacks or heaps of granite boulders. The two prominent tabular hills of weathered diorite, Dala and Kogon Dutsi,[17] within the walls of Kano, have a peculiar interest of their own which will be related in the sequel (p. 201). Northward between Kano and Kazaure the undulating sandy plain is diversified only by the low flat-topped hillocks of earthy grit and conglomerate in the neighbourhood of Sai and Ingogo and by the broken ridges of amethystine quartz which rise from the plain immediately south of Kunchi. Kazaure is set in the midst of rocky ridges of blue quartzite with red sandy drift filling up the valleys and banked against the slopes of the hills. Around Rauni rise low extended flattened ridges, which appear to be composed throughout of dark red vesicular ironstone. At Tummas, half way to Ingawa, low granite knobs and heaps of boulders project above the surface, but from Ingawa north- westward to Katsina the undulating plains are featureless, with no prominent granite hills or kopjes to break the monotony of the landscape. Smooth surfaces of rock are here and there exposed level with the plain or in the channels of the streams, but otherwise the deep sandy drift which covers the surface effectually obscures all the minor irregularities.

Around Katsina both sandstones and granites are exposed upon the surface of the plain, but it is not until the neighbourhood of Kurefi is reached that a decided change takes place in the character of the scenery. From Kurefi to Runka the track leads through rocky granite country which assumes its wildest aspect in the neighbourhood of Tummo, where the landscape, as far as one can see, is made up of an assemblage of low rounded hills, domes, tors, heaps of boulders, perched blocks and smooth surfaces of granite, with no particularly high or prominent peaks. On the margin of the mass near Kurefi and Runka the aspect of the country is smoother; the turtlebacks and rounded hills are separated by narrow stretches of plain, and often half-buried under the sandy drift which is banked up against their slopes. From Runka south-westward to Kotorkoshi, and thence north-westward to Karakai, the landscape assumes its familiar aspect of a gently undulating thinly-wooded surface, diversified by isolated groups of granite hills which, at Duru and Kotorkoshi, rise abruptly and picturesquely from the drift-covered plain. A belt of broken hilly country stretches N.N.E. and S.S.W. between Karakai and Maradu, parallel with the strike of the quartzites, phyllites, and gneisses out of which the hills are carved. Immediately beyond Maradu knobs and hummocks of volcanic agglomerate project from the surface of the plain, while northward the track leaves the hummocky crystalline floor in the neighbourhood of Gora and follows the level swampy plain of the Gulbin Gandi as far as Dankaiwa. At Dankaiwa, in the cliff which faces the river, is the first exposure of the red earthy sandstones of Sokoto, while at Dampo, a little farther on, the first flat-topped sandstone hill rises above the sandy plain. From Dampo the track again runs along the swampy valley of the river as far as Rara, whence it leads across undulating park-like plains to the broken sandstone hills of Sokoto.

The northern and western portions of Sokoto province, which consist of a dissected plateau of horizontal sandstones, possess in general all the familiar scenic features of such a formation as already described from other parts of the Protectorate. The apparent differences are differences more in degree than in kind. Like the Niger above Lokoja, the Benue in its lower and upper course and the Gongola above Gombe, the Gulbin Kebbi or Sokoto river flows in a broad flat-bottomed trench-like valley between two steep and worn escarpments, which lead up to the plateau on either side. The breadth of the valley of the Gulbin Kebbi is, however, out of all proportion both to the height of the bounding walls and to the volume of the river itself. The floor of the valley is usually several miles in breadth, while the cliffs on either side rarely reach 200 feet in height. In the rainy season a sluggish flood covers the bottom of the valley, but in the dry season the river is represented by one or more diminutive streams, which disappear from time to time in stretches of swamp. The continuity of the flat-topped escarpments is much broken by lateral valleys, and here and there the vertical walls are replaced for long distances by steeply-rounded rising ground. The tributaries of the Gulbin Kebbi, where they flow through sandstone country, are likewise bounded by worn and broken escarpments. Similar broad flat-bottomed valleys with diminutive streams are common also within the French Sudan to the north of Sokoto, and are there generally known as “dallols.” Of them all, however, the Gulbin Kebbi possesses the greatest volume of water, which is contributed practically entirely by its numerous southern affluents which rise on the high and well-watered plains on the borders of Kano, Zaria, Kontagora and Sokoto.

PLATE V

The plateau areas between the larger valleys are themselves much dissected, especially in the east and north, by the smaller tributary streams. In the west there are some fairly extensive stretches of continuous tableland, whose gently undulating and thinly-wooded surface is diversified by occasional flat-topped and conical hills, the relics of a former plain which has now been almost entirely removed in the course of denudation. To the north and north-east of Sokoto the irregularities of the dissected plateau are softened in contour by accumulations of blown sand which covers the floors of the smaller valleys and creeps up their lateral slopes, rounding off the steeper cliffs of the flattened ridges on either side.

[Footnote 1: Mungo Park; Denham and Clapperton; R. and J. Lander; Laird and Oldfield; Allen and Thomson; Baikie; Crowther; Barth; Vogel; Passarge; Lenfant; Lugard; Wallace; Boyd-Alexander.]

[Footnote 2: “Hausaland,” in the general sense of the term, may be taken to include the provinces of Sokoto, Kano, Kontagora, Zaria and Bauchi.]

[Footnote 3: _Cf._ Laird and Oldfield, _Expedition to Africa_, 1837, p. 136. The hills between Itobe and Igbo are here erroneously described as the eastward prolongation of the Kong Mountains.]

[Footnote 4: _Cf._ Vandeleur, _Geographical Journal_, X, 1897, p. 349.]

[Footnote 5: _Vide_ Lenfant, _Le Niger_, 1905, illus., pp. 72, 73.]

[Footnote 6: Lenfant, _op. cit._, p. 78 _et seq._]

[Footnote 7: Boyd-Alexander, _From the Niger to the Nile_, 1908, p. 47.]

[Footnote 8: An excellent illustration of this peculiar type of scenery (Inselberglandschaft) is given by Bornhardt, _Deutsch-Ost- Afrika—Géologie_, Bd. VII, 1900, Taf. 3, p. 30.]

[Footnote 9: Erroneously designated lava by the earlier explorers.]

[Footnote 10: _Cf._ Boyd-Alexander, _From the Niger to the Nile_, 1908, p. 86.]

[Footnote 11: _Cf._ Boyd-Alexander, _op. cit._, p. 46.]

[Footnote 12: _Cf._ Whitlock, “The Yola-Cross River Boundary Commission,” _G. J._, XXXVI, 1910, p. 426.]

[Footnote 13: _Cf._ Boyd-Alexander, _op. cit._, p. 98.]

[Footnote 14: _Ibid._, p. 94.]

[Footnote 15: Barth, _Central Africa_, 1857, II, p. 355.]

[Footnote 16: _Cf._ Boyd-Alexander, _From the Niger to the Nile_, pp. 112, 164.]

[Footnote 17: _Cf._ Barth, _Central Africa_, 1857, p. 96.]