THE RAISIN INDUSTRY. 71 



regular stratified rocks, impenetrable to the roots of the vines, and 

 impervious to water. Other hardpans again are softer, and allow the 

 vine roots to penetrate more or less readily, while some again are so 

 soft that they dissolve in water and make good soil for the vines. If 

 the hardpan is very shallow, it may pay to blast holes through it, in 

 order to allow the roots of the vines to penetrate to lower soils. But 

 if the hardpan is thick and hard, and if there is no immediate pros- 

 pect of subirrigation, it is better to use such land for some other pur- 

 pose than for raisin-vines, which will only pay properly if grown 

 under the most favorable circumstances, and on the best and deepest 

 soils. 



As to the nature of the hardpan, a few remarks may prove of interest 

 The hardpan can best be compared to a stalactite formation similar to 

 those found in various caves. It has been formed very much in the 

 same way as they were. In caves the rainwater, that seeps down 

 from the top surface, dissolves various substances, especially carbonates 

 (and silicates even) which again are deposited on the underside of the 

 cave roof. This precipitation of hard material is caused both by evapo- 

 ration of the water, as well as by attraction and adhesion. Such redep- 

 osition of dissolved minerals is seen for instance if solutions of salt 

 in water are passed through tasteless and clean sand. The water will 

 come through sweet and tasteless, the salt having adhered to the 

 surface of the sand grains. Similarly, if a hole is dug near the sea- 

 shore in the sand, the salt water will seep through, and form a well of 

 more or less tasteless drinking water. In the formation of hardpan, 

 this is exactly what has taken place. The rainwater has dissolved 

 certain elements, such as carbonates of lime, or carbonates of sodium 

 and various other salts, and in its way through the lower strata of the 

 soil these dissolved elements have again been taken up by the sand 

 and cemented it together. Thus it is explained why hardpan upon 

 examination is so often found to resemble sand or sandstone: the 

 lower sandy strata of the soil have been especially effective in causing 

 the lime in the water to adhere to the numerous surfaces of every 

 individual grain of sand. In hog-wallow districts the hardpan is 

 found principally between the individual hog-wallows, but rarely in 

 or under them. The rainwater has here carried the minerals in the 

 soil to the deeper places betweeen the hog-wallows, in which it has 

 accumulated to a greater extent than anywhere else, and thus formed 

 a heavier hardpan. In flooding the hog-wallows, the top of every 

 hog- wallow is seen to settle and fall in, there being no hardpan below 

 it, if the sides of the hog-wallow are steep. Where the hardpan con- 

 sists principally of lime compounds, its chemical composition is not 

 detrimental to the vines. But where the hardpan is cemented by 

 alkalies more or less soluble in water, these deleterious substances will 

 dissolve and rise to the surface to the great detriment or even to the 

 total destruction of the vineyard. 



Comparative Value of Soils. The river bottom soils, or soils formed 

 by the deposit of creeks, are with few exceptions rich and deep, and 

 contain in abundance all the elements necessary to produce a superior 

 Muscat grape. Such soils are, however, often injured by subsoils 



