421 



extends, with little interruption, from Shucknell Hill, four miles and 

 a half N.E. of Hereford, to Flaxley, near Westbury-on-Severn. He 

 shows that the formation consists of beds of limestone and shale, rest- 

 ing at May Hill on a central ridge of greywacke, and along its 

 western boundary underlying the old red sandstone ; but that along its 

 eastern, it is overlaid by that formation, the Newent coal-field, and 

 the new red sandstone. He also states that great irregularity occurs 

 in the dip of the beds. 



Old red sandstone. — This formation is shown to occupy a very great 

 part of southern Herefordshire and the district bordering on the Forest 

 of Dean. It is stated to consist of beds of sandstone, conglomerate, 

 nodular limestone, and clay ; the limestone occurring in the lower 

 part of the formation, and the conglomerate principally in the middle. 



The next deposit described is the carboniferous limestone. It is 

 shown to surround the coal-field of the Forest of Dean, with the ex- 

 ception of a district near the south-eastern extremity of the basin, 

 where it is cut off by a fault. The lower beds are said to be of a 

 crystalline texture, and separated from the upper or argillaceous and 

 sandy beds by a stratum of iron ore. From the southern extremity 

 of the coal-field, the limestone extends in a south-west direction by 

 Chepstow and Caerwent to Magor. 



Coal-measures. — The author then enters into a minute detail of the 

 beds composing the coal-field of the Forest of Dean. They are stated 

 to be divisible into two series ; the lower characterized by the seams 

 of coal being separated from each other by strata of coarse sandstone ; 

 and the upper, by the seams of coal being separated by strata of ar- 

 gillaceous shale. The field, it is said, rests upon the mountain lime- 

 stone. The author next describes the Newent coal-basin, and shows 

 that it differs in geological position from that of the Forest of Dean, 

 by resting along its western and southern edges upon the transition 

 strata, and along its north-western upon the old red sandstone ; and 

 that it is overlaid at its eastern boundary by a conglomerate belong- 

 ing to the new red sandstone. Two outliers of the Forest of Dean 

 coal-field are also alluded to, and shown to occur at Howl Hill and 

 Tidenham Chase. 



New red sandstone. — In describing this deposit, the author acknow- 

 ledges the great difficulty he experienced in endeavouring to separate 

 it from the old red sandstone, when in contact with that formation. 

 He states, that the only characters on which he could rely, were the 

 absence of beds of conglomerate, of flagstone and of gray clav con- 

 taining nodules of cornstone ; the presence, near Tidenham, of the 

 conglomerate belonging to the magnesian limestone ; and the occa- 

 sionally well-defined unconformity in the dip of the strata in the 

 older and newer deposits. 



The author then shows that extensive beds of superficial gravel 

 occur in the neighbourhood of Hereford, and along the valley of the 

 Wye as far as Ross. The boundaries of these accumulations are 

 accurately defined upon the map ; and he is of opinion, that the 



