North of the Comcraghs, across the valley of the Suir, in Tipperary, the broad cone of Slievenaman (2295 ft.) rises solitary and dominates the country for many miles. Not many miles west of the Comcraghs, the Knock- mealdown Mountains form a bold east-and-wcst ridge, dropping into the Suir valley on the north and the valley of the Blackwater on the south. They present a bold row of peaks of over 2000 ft., the highest point being 2609 ft. A picturesque road climbs across the centre of the range, ascending to over 1100 ft.
A few miles north-west of the Knockmealdowns, across a limestone trough in which lie the celebrated Mitchelstown Caves, a loftier east-and-west ridge, the Galtees, towers up, with steep slopes especially to the north and west. They attain in Galtymore an elevation of 3015 ft.-a height reached elsewhere in Ireland only in Kerry and Wicklow. This is a compact and picturesque mountain group, with several fine coombs embosoming lakes on the northern slopes. Lower hills (up to 1700 ft.), known as the Ballyhoura Mountains, continue far to the west, and are conspicuous from the. train about Charleville, where the line to Cork passes round their flank and turns south to Mallow.
In North Tipperary (Bed and Breakfasts, Tipperary, Ireland), some 20 to 30 miles north of the Galtees, there is a large area of hilly country stretching north-westward to the Shannon at Killaloc and north-eastward to the Devils Bit, near the borders of Offaly. Much the highest point is Slicvc Kimalta, or Keeper Hill (2278 ft.). A western outlier of this range, the Arra Mountains, separated from the main mass by a deep narrow valley-possibly an old course of the Shannon-forms the eastern side of the deep Shannon gorge, where that river, passing between high hills, at length escapes from the plain and plunges down from Lough Derg to the sea.
The western side of the Shannon gorge is formed by a group of hills known as Slieve Bernagh (1746 ft.). Though separated from the Arra Mountains by the Shannon and Lough Derg, these two really form a single hill – group, through which the river has cut its way.
The river systems of Munster divide themselves into two groups. In the northern half the Shannon is the dominating feature, flowing south-westward through a wide plain only occasionally interrupted by hills, and draining the whole of Limerick, the greater part of Clare, and half of North Tipperary (Hotels, Tipperary, Ireland). In the southern
half the drainage has been profoundly affected by the east-and-west folding of the country, and the rivers conform in a very definite manner to conditions imposed by this ancient crumpling of the crust.
Munster touches the Shannon first where the Little Brosna river, separating Kings County from Tipperary, runs into the main stream at Meelick, where one of the few rapids of the Shannon interrupts the placid course of the river, and locks have been built to assist navigation. Thence the broad slow stream meanders down to Portumna, where it enters Lough Derg, the lower two- thirds of which belong wholly to Munster. Lough Derg is some 32 miles in length, and generally about l 1/2 mile wide, with occasional inlets on either hand which increase the width to about twice that amount-at one point to 9 miles.
Lough Derg is, in fact, a great river expansion rather than a lake, and has been produced mainly by solution of the limestone which forms the greater part of its shores. The upper end is shallow, with flat limestone country on either hand, but as one proceeds down its winding island- studded course the scenery gets bolder on account of the approach of uplands which close in on either hand, till at the lower end the lake lies in a gorge between steep hills. These hills are formed of slates, and the fact that the river has cut this deep gorge through them instead of following a different course eastward or westward across the low limestone country is the most remarkable feature of Shannon topography. Its course is believed to date from a time when the great limestone area to the north stood much higher, so that the route over Lough Derg formed the easiest way to the sea. The plain was lowered by denudation as the Shannon cut its way downward, the rate being determined by the rate at which the gorge could be cut, since this was the, outlet for the removed material. As seen now the topography of the middle Shannon is very striking. The traveller standing at Athlone sees all round him nothing but plain, save to the southward, where a distant rim of hills breaks the line of the horizon. Towards these hills the river takes its course. As one advances, the hills close in to right and left, and still the river goes straight on for their centre. One gets the idea that the Shannon is running uphill. As Lough Derg is entered, it is clear that the stream is heading for a deep narrow notch which appears far in front. Presently the hills approach so as to descend to the waters edge on either hand. Their dark heathery summits rise to 1500 and 1700 ft. on the east and west. And then at Killaloe the lake- like expanse narrows and the Shannon goes foaming over ledges of rock to resume further down its placid flow over the level limestones. Having in its middle course pursued its way for 130 miles over the Limestone Plain with a fall of only 51 ft., it now drops 97 ft. in 18 miles to reach sea-level at Limerick.
The Suir, rising in the hilly region of North Tipperary (Holiday Homes, Tipperary, Ireland), flows southward through flat limestone country past Thurles, and at Caher passes close by the eastern end of the high ridge of the Galtees. Ten miles further on, at Newcastle, it finds itself in a cul-de-sac, caused by the dominance of the east-and-west ridges already referred to frequently. The Suir may at one time, when the limestone floor occupied a higher level, have flowed on between the Knockmealdowns and Comeraghs to the sea at Dungarvan or Youghal. But now, carried off eastward by a tributary of the old consequent river that has its lower reach in Waterford Haven, it follows the limestone trough, above which the more resisting sandstones form mountain land,
bends sharply northward, and then turns eastward along the base of the. Comcraghs, through Clonmel and Carrick-on-Suir (where, it becomes tidal) to meet the sea at Waterford Haven. The monotony of its marshy upper reaches is fully compensated by the beauty of its middle course about Caher and Clonmel, with the lofty ridges of the Galtees, Knockmealdowns, and Comcraghs rising around. The west-to-east course of the Blackwater is one of the most striking features of the geography of the South of Ireland. Rising on the boggy Coal-measure hills of North Kerry, it flows south for some 10 miles to the foot of the high hills which are grouped round Caher- barnagh (2239 ft.). Then it strikes the upper end of a limestone trough which it follows almost due eastward for nearly 60 miles to Cappoquin. Then, deserting this trough, which continues eastward to meet the sea . at Dungarvan, it turns abruptly southward, cuts through the barrier of slates which all the way has formed its southern bank, and flows for 15 miles through an interesting and picturesque gorge in places 400 to 500 ft. deep to reach the sea at Youghal. This east- and-west trough is the best marked of those which characterise the South of Ireland, and is utilised from end to end by railways and main roads. A minor parallel valley lying a few miles south of the eastern part of the trough is occupied by an important tributary, the River Bride, which enters the main stream a few miles below Cappoquin. The gorge between Cappoquin and Youghal represents one of the few portions of the ancient north-to-south drainage channels which has been continuously occupied by a river. In old days it bore to the sea the rains which fell on areas to the north- ward ; possibly the Suir once continued its southern course, and passing between the Knockmealdowns and Comeraghs, debouched through this gorge ; now the lowering of the limestone troughs by solution has diverted it to the eastward, and the old gorge serves to discharge waters which, in their turn, reach the ocean far to the cast of their gathering-grounds.