ance of the earth changes ; instead of a blue, we have a dark 

 red clayey soil, formed from the decomposition of the argilla- 

 ceous schists which are seen alternating with, and always upon 

 the confines of the sandstone, which predominates as you ascend 

 the Conewago hills. It changes its aspect at almost every step ; 

 it is sometimes a hard ferruginous quartz rock, compact, white, 

 red, gray, and of a variety of hues, even to a black ; at other 

 times it is a well-eharacterised sandstone, with small crystals 

 of hyalin quartz. The grains of quartz vary in size, and it 

 passes into a conglomerate; the base being argillaceous, red, 

 with perceptible scales of mica, the imbedded pebbles are gene- 

 rally rolled quartz, varying from the size of a millet seed up. 

 It is occasionally of a light color, free from iron. The imbedded 

 pebbles are uniform in size ; the whole rock is hard, and em- 

 ployed in the county for making millstones for the various uses \ 

 to which the Burr millstones are employed. Compact ferrugi- 

 nous varieties of the rock are used for gudgeons or boxes sup- 

 porting the axis of water and other wheels ; they are found to 

 answer this end admirably well, and have superseded those of 

 iron or steel. In building furnaces for the smelting of iron ores, 

 a proper hearth stone is considered a very great desideratum 

 The crucible is often built of bad materials, causing the furnace 

 to be put out of blast at very short intervals, to the very great 

 loss of the proprietors. The campaign of certain furnaces in 

 our country is called good if the hearth has resisted one year ; 

 we know of furnaces that have been in blast constantly for 

 twenty years, and one of the principal causes of this astonishing 

 success is undoubtedly owing to the very great attention that 

 was paid to the choice of the hearth stones. We will not here 

 discuss the merits of such materials, but let it suffice to say that 

 the quartz rock of York county has the appearance of being 

 well fitted for this purpose, and by a proper choice we think 

 that superior hearth stones might be here procured, if not equal 

 to those found and used in the Hartz mountains, much better 

 than many we have seen used for these ends in the United 

 States. 



The greywacke quartz rock caps the summit of the general- 

 ity of the highlands throughout the county, there are also hills 



