22 POPULAR GEOLOGY. 



to have been brought down to the sea in which they were deposited from 

 a distance, by rivers and ocean currents. They are the first pioneers of 

 that gigantic flora which reached its full perfection in the middle coal 

 measures. 



The dip or inclination of strata. If we go into any of oiu- 

 quarries, or examine the surface of any exposed rocks we shall see that 

 they are not exactly level, but that they incline in some direction or other. 

 This inclination is called the dip of the strata. The general dip of the 

 strata of this neighbourhood accords with Professor Phillip's observations, 

 viz., about 3 degrees to the south-east, or as the miners say " it falls 

 about one yard in twenty towards the ten o'clock sun." Thus while the 

 grit-rocks occupy the high moorlands of Ogden and Warley, where they 

 crop, or strike out towards the west, at an elevation of 1,450 feet above the 

 level of the sea at Skirden Head, and other places, they gi-adually incline 

 down towards Halifax, and disappear under the semicircular range of hills, 

 of Ringby, Beacon, Southowram, Rastrick and the Ainleys, and at length 

 just below Elland the Calder flows over them at a height of only 250 feet 

 above the level of the sea. Here, we see, they have fallen 1,200 feet in 

 about seven or eight miles direct south. They dij) still more rapidly 

 towards the south-east. I have given the above illustration of the dip of 

 the strata because any person who wishes to study the subject may 

 examine it easily for himself by taking a pleasant afternoon's walk from 

 Halifax to Ogden Kirk, or from Halifax to Elland, without any other aid 

 than an ordinance survey map. A hammer to detach specimens of rocks, 

 and a clinometer compass to measure the dij), &c., are hoAvever indispeusibJe 

 for accurate observation. 



The Lower Coal measures, occupy the slopes of the above range of hUls 

 and the valleys of Shibden and Mytholm, Cromwell Bottom and Brighouse. 

 This series of beds consists of a great thickness of shale, interstratified 

 with shelly rag and beds of coal, fire clay, and a few layers of ironstone, 

 altogether nearly 600 feet in thickness. The following section of the 

 Lower Coal measures, is taken from the Halifax Museum list (strata of 

 Bank Top Pit.) 



FLAGSTONE ROCK ABO^T^ Feet. Inchs. Feet. Inchs. 



1 Shale and Rag 192 



2 4 score yards Band Coal j 6 



3 ShaleandRag | 77 



4 48 yards Band Coal 01' 6 



