MAKYLAXD WEATHEK SERVICE 329 



including pasture types, hence dairying is extensively conducted 

 by the farmers along the railroads which cross this region. The 

 same soil and farm characteristics extend into Carroll County, es- 

 pecially in the part east of Parr's Eidge. 



Valleys. — The rock matter may be reduced to a soil of a high 

 degree of fertility with both composition and texture of a favorable 

 character. In this class fall the highly fertile valley lands along 

 the Monocacy and its tributaries, in the Middletown Valley, and in 

 the Hagerstown Valley, between the Blue Eidge and North Moun- 

 tain. Much of these lands are of limestone origin, and rank among 

 the richest of the State. Special bands of soils differing from the 

 type occur in sections where rocks of different composition form 

 outcrops in the general mass of more uniform character; such is 

 the belt of "red soil" in Frederick County, caused by the presence 

 of a rock containing more iron than is usually present in the vicinity. 

 A few miles above the "Fall-line" in the vicinity of Gaithersburg, 

 there is an outcrop of serpentine, that is almost useless for farming, 

 1 icing but little better than that mentioned before as forming the 

 "Bare Hills" area. 



The limestone soils are chiefly formed of the residue left behind 

 when the more soluble portions of the original rock were carried 

 away in flowing water. The process is continuing along the surface 

 of the limestone ledges, but so slowly that it is not conspicuous. 

 Soils so derived are much benefited by top dressing with burnt 

 lime. The explanation lies primarily in the physical action of the 

 lime, not in its fertilizing action. The soils are fine loams approach- 

 ing more or less closely to clay condition, and as such are largely 

 composed of the fine silt particles that become flocculated, or coagu- 

 lated by the action of the caustic property of the lime. The result 

 is to make the soil somewhat more of the nature of a coarser loam 

 in especial reference to the drainage and plant-growing power. Very 

 much the same result is attained when manure containing large 

 amounts of plant remains, bedding or other trash, is plowed into a 

 clay soil ; the addition of vegetable matter loosens the soil and gives 

 it a chance to become better drained, and lets in the air, all aiding 

 to increase the succeeding crops, as compared with those before the 

 treatment. 



