,85,. AGRICULTURAL MUSEUMS. 373 



and reaping at the proper seasons, and that is all. But, possibly, 

 a little more intimate acquaintance with them would be found to 

 repay the trouble. Now this museum of ours brings clearly out the 

 fundamental fact that soils are the outcome of the disintegration of 

 rocks, and it does this in the simplest manner possible, i.e., by showing 

 every stage in the process from the rock to the resultant soil. The 

 parent rocks may be distant, as in the case of alluvial soils, or the 

 glacial subsoils with which the lowlands of this district are so largely 

 covered, but, near or distant, the relationship exists. The scheme 

 reaches even further back than the rock. Some rocks are of com- 

 paratively simple structure — for instance. Sandstone ; others are 

 comparatively complex, as Gneiss, and Granite. In the first row of 

 boxes are placed the minerals which enter into the composition of 

 the common rocks, as rock crystal, calcite, felspar, hornblende, mica, 

 augite, olivine. In the second row follow a few of the typical rocks, 

 built up out of one or more of these minerals, those common to the 

 district, as Old Red Sandstone, quartz, limestone, gneiss, granite, 

 dolerite, being preferred. A few of these typical rocks have been 

 selected to illustrate the process of decomposition. In succeeding 

 rows of boxes the gradual formation of the more familiar soils is 

 illustrated, and it is shown whether this happens with or without 

 chemical change. Sandstone, dolerite, and granite already occupy 

 the fourth, fifth, and sixth rows, and the other rocks of the county 

 remain to be added. 



The composition of the minerals which make up the rocks is 

 clearly stated both in words and in chemical symbols, and every 

 stage in the progress of decay is made plain in the same way. It. 

 thus appears that soils are largely made up of alumina and silica 

 According to the preponderance of one or other of these, the soil is 

 known as sandy or clayey. When neither is in excess the result is 

 a loam. In addition, there are often minute varying proportions of 

 iron, lime, manganese, sodium, potassium, sulphur, and in some 

 cases phosphorus. In the last of these boxes, illustrating the process 

 of decomposition, the surface layer, the soil proper — darkened by 

 the decay of animal and vegetable organisms (humus) — is placed, 

 A rough outline of one of these cases which will show the arrange- 

 ment followed is given on the next page : — 



