82 JOTTINGS OF A GENTLEMAN GARDENER 



Limestone, as it is called, is also good, but usually teeming 

 with fossils. Devonshire Limestone is quite good, Cre- 

 taceous Limestone (Chalk, etc.), is fair, and Tertiary 

 Limestone is fair. 



Jurassic Limestones must only be considered fair for 

 rock-garden making. Some of the oolites (Upper Jurassic), 

 are quite valuable for the purpose, but not nearly as 

 valuable as people sometimes make out. Many of the 

 oolites are too brashy, too fossiliferous, and too easily 

 disintegrated. The stone from the series knows as " The 

 Portland Beds " is the best. If, on the other hand, other 

 oolites have to be used, the hardest, closest-grained samples 

 should be chosen. Beds of hard oolite are generally found 

 at the base of every rubbly stone. This is also the case 

 to some extent with the Tertiary Limestones, such as the 

 stones known as " Crags." If these have to be used, always 

 obtain the hardest samples. On the other hand Limestones 

 which are very crystalline, as the Derbyshire Limestone 

 sometimes is, should not be used. 



Tufa : This is quite fairly good if obtainable. But in 

 my view does not look very natural. Holes may be made 

 in it, or through it, and filled with soil, and the plants set 

 in them. They thrive quite well. 



Artificial Stone : Burnt clay, burrs, and slag have been 

 used in some districts where stone is scarce, but the practice 

 cannot be recommended. Those who have seen rock- 

 gardens made of this class of material will know how ugly 

 it looks, and plants seldom thrive there. Allied to these 

 is the manufactured rock-garden stone. This is usually 

 made into rough irregular pieces. It consists of a mixture 

 of stone, sand, and cement. It may have a more or less 

 natural appearance, but I would far rather do without it 

 if possible. Of course if there is nothing better available, 

 it must be pressed into service, but it is a good rule to use 

 the very smallest quantity possible. If I were in a county 

 where stone is scarce I would rather use artificial concrete 

 rocks than such awkward materials as burnt clay, burrs, 

 or slag. 



