AGRICULTURE 



away south to Barnard Castle. The soils lying directly on these are usually 

 thin and poor sandy soils on the sandstones, and poor stiff clays on the shales 

 of this system. While there are considerable areas of these sandy soils, there 

 are thousands of acres of these poor clays, but Boulder Clay covers the 

 greater part of this system, affording soils which are usually poor and shallow 

 clays, but with some good sandy loams on the Glacial Sands. Very large 

 areas of these, to the west, are overlaid by moorland and peat. The Mill- 

 stone Grit occupies large areas of the high-lying land above the upper valleys 

 of the Wear and the Tees in the west of the county, while this is the 

 principal underlying formation for a few miles to the north of the Tees from 

 Barnard Castle to Gainford. In this latter district dryer clay loams are found 

 on the overlying Boulder Clay, but there are extensive tracts of poor sandy 

 soil on the sandstones of this formation, and some poor clays on the shales 

 with which the sandstones are interbedded. These poor sands and clays 

 usually occur on high-lying areas, chiefly as moorland, much of which is 

 of a peaty character. The sandy soils are usually very deficient in plant 

 food, and are in great need of potash manuring, as has been shown by 

 recent experiments. The valleys of the Wear and the Tees in this western 

 part of Durham, as well as the flanks of the hills, lie chiefly on the 

 Mountain Limestone, which here consists of a great succession of sand- 

 stones and limestones, the former to the largest extent. Strong reddish soils 

 of a good character are formed from the limestones, which are especially 

 healthy for stock raising, while poorer sandy soils are formed from the sand- 

 stones. Again, very much of this formation is overlaid by peat and moor- 

 land. The extent of the Boulder Clay deposits may be realized from the 

 fact that of about 435,000 acres under crops and pasture (exclusive of moun- 

 tain pasturage) in the county, at least 250,000 acres lie on Boulder Clay. 

 This differs from a sedimentary clay in that it was deposited under ice 

 during the Glacial Period, without being subjected to weathering agencies. 

 Its character usually depends to a large extent on the underlying and 

 adjacent rock, although it may contain other rocks transported from con- 

 siderable distances. These soils are, as already stated, of a better character 

 in the south-east of the county, where they are derived largely from New 

 Red Sandstone, but are as a rule poor and cold when derived from the shales 

 of the Coal Measures. When they contain limestone rock they are usually of 

 a valuable character. The great bulk of these Boulder Clay soils in the 

 county however are thin, and are lying on a poor clay subsoil. On these 

 soils deep ploughing is inadvisable, as this mixes with the small amount of 

 surface soil the poor and unhealthy subsoil material. Some good sandy loams 

 are found on the Glacial Sands and Gravels associated with this clay, which in 

 places extend to quite considerable areas. The areas of good alluvial soil in 

 the river basins are not extensive, as there are practically no wide and open 

 valleys. 



A reference to Professor Lebour's geological map^ will show the relative 

 position of the underlying formations, but not of the drift deposits. 



y.CH Dur. i. 



363 



