Wiestling.] ^gQ [December. 



back of the South Mountains ; and a closer date for the Lignite of 

 Mont Alto. 



In Fig. 11, plate X, where such a reconstruction of an ancient sur- 

 face of the Great Valley is attempted, there is noticeable, 1. How 

 vast an amount of Palaeozoic rock-substance has been swept away ; 

 and, yet, that amount represents only the waste of the four lower 

 Palaeozoic formations ; superposed upon these at a still older date, 

 eight others, including the Coal Measures, must have formed their 

 surfaces; supposing no cataclysm. 2. How fine a chance was given 

 for collecting towards the present surface the ferruginous elements 

 of the slowly decomposing and cavernous-becoming limestone layers ; 

 and 3. How the erosion must have acted, for some reason or other, 

 more upon the Pala30zoic surface outside, than upon the Palaeozoic 

 surface inside the limits of the New Red ; the reason probably being, 

 simply, this : that the latter was under the New Red waters, and 

 was being covered up, while the other was being eroded ; but the 

 erosion had not yet brought the valley surface down to the New Red 

 water-level, when the uplift of the New Red took place. After 

 which, the two erosions went on with different velocities proportional 

 to the different solubilities, &c., of the Silurian limestone, and of the 

 New Red sandstone, formations. 



As for the lignite, therefore, it must have been subsequent to the 

 erosion of the New Red, that is, certainly not older than the Cretace- 

 ous lignites of the United States ; and when we consider the im- 

 mense lapse of time needful for carrying the Silurian Valley surface 

 from a level with the tops of the New Red Hills, down to a level 

 with their feet, we may well believe that the precise condition of the 

 ore deposits as we see it, while it commenced before New Red times, 

 was not perfected until the latest tertiary age, and, therefore, this 

 last must be the age of the lignite — apart from all consideration of 

 fossils. 



[Captain Geo. B. Wiestling, Superintendent at Mont Alto, writes 

 under date of Jan. 20, 1865, as follows : 



" Our pit No. 1, primitive iron ore (Pond-bank), lies at the south- 

 west foot of the 'Little Mountain,' close by the township road lead- 

 ing from Greenwood, on the Baltimore turnpike, to Altodale, near 

 our works. About seven hundred (700) feet south of this pit, 

 we have another larger pit. No. 2. These are about three-fourths 

 of a mile west of a spur (Mont Alto) of the South Mountain. The 

 neighborhood is dotted with a number of ponds, from which it de- 

 rives its name, ' Pond-bank.' In order to drain the water from and 



