116 
HUDLESTON: EXCUKSION. 
rivers of the West Riding have to pass on their way into the Vale 
of York. Most of these earthy varieties contain probably about 
25 per cent, of carbonate of magnesia ; they are quite useless as 
building stones, but make excellent mortar. This porous, spongy 
sort of rock passes into yellow crystalline dolomite, frequently 
showing coloured bands ; the more ferruginous varieties being- 
studded with radiations of a metallic oxide, which is probably 
magnetite.* No purer form of dolomite than this would seem to 
occur in the Knaresboroug'h district. But a few miles further 
south the crystalline dolomites of Huddleston Quarry are famous ; 
there occurs also in Towton Field a form of Magnesian Limestone 
which is concretionary in small ovoids, almost resembling an 
oolite. 
The Middle Marl succeeds the Magnesian Limestone, and in 
some cases must overlap it. This sub-division consists of red 
marls, and soft red sandstone, with some gypsum. Above it some 
small remains of the Upper Limestone are visable in a cutting to 
the west of Knaresborough. 
The association of gypseous marls with beds of magnesian 
limestone is worthy of attention as having an important bearing on 
the origin of magnesian limestones, regarding which there are so 
many rival theories. Is the double carbonate a contemporaneous 
product, or the result of subsequent dolomitisation ? Some are 
disposed to regard the formation of magnesian Kmestone as the 
Sir William Plumpton, the commander of the Knaresborough contingent, was 
taken prisoner, and his son slain along with many others of less degree, so 
that days of mourning fell upon the manor and forest. 
The bloody Lord of Skipton, Shakespeare notwithstanding, had fallen in a 
prehminary skirmish, but his youthful son, afterwards known as the Shepherd 
Earl, found refuge under the care of Sir Launcelot Threlkeld in the wilds of 
Saddleback, whence he emerged to resume his rank and estates on the final 
triumph of the House of Lancaster. 
The part played by the royal castles of Knaresborough and Skipton, during 
the Parhamentary wars, is too well known to require fuilher mention. 
* These markings, on examination are seen not to be dendritic : still they 
may contain some oxide of mangnanese. 
