_Stony Loam._--Like the gravelly loam the stony loams are one-fourth to three-fourths sandy, silty or clay loam, the remainder being rock fragments of larger size than the gravel. These fragments are sometimes rough and irregular and sometimes rounded. The stones interfere seriously with tillage, and naturally the soils are best planted with forest or fruit. _Clay Soils._--Clay soils are mixtures of sand, silt, clay and humus, the clay existing in quite large quantities, there being a greater preponderance of the clay characteristics than in the clay loams; they are very heavy, sticky, and difficult to manage. Some clay soils are not worth farming. Those that can be profitably tilled are adapted to wheat, corn, hay and pasture. _Adobe Soils._--These are peculiar soils of the dry West. They are mixtures of clay, silt, some sand and large amounts of humus. Their peculiar characteristic is that they are very sticky when wet and bake very hard when dry and are, therefore, very difficult to manage, though they are generally very productive when they are moist enough to support crops. _Swamp Muck_ is a dark brown or black swamp soil consisting of large amounts of humus or decaying organic matter mixed with some fine sand and clay. It is found in low wet places. _Peat_ is also largely vegetable matter, consisting of tough roots, partially decayed leaves, moss, etc. It is quite dense and compact and in some regions is used for fuel. HOW WERE SOILS MADE? As a help in finding the answer to this question collect and examine a number of the following or similar specimens: _Brick._--Take pieces of brick and rub them together. A fine powder or dust will be the result. _Stones._--Rub together pieces of stone; the same result will follow, except that the dust will be finer and will be produced with greater difficulty because the stones are harder. Some stones will be found which will grind others without being much affected themselves. _Rock Salt or Cattle Salt._--This is a soft rock, easily broken. Place on a slate or platter one or two pieces about the size of an egg or the size of your fist. Slowly drop water on them till it runs down and partly covers the slate, then set away till the water dries up. Fine particles of salt will be found on the slate wherever the water ran and dried. This is because the water dissolved some of the rock. _Lime Stone._--This is harder. Crush two samples to a fine powder and place one in water and the other in vinegar. Water has apparently no effect on it, but small bubbles are seen to rise from the sample in vinegar. The vinegar which is a weak acid is slowly dissolving the rock. The chemists tell us water will also dissolve the limestone, but very slowly. There are large areas of soil which are the refuse from the dissolving of great masses of limestone.