SOS DEEP-LYING MARL. 



manner as is now done in coal mines. When sucli means shall be 

 resorted to, it is probable that there will be but a small proportion 

 of all the great tide-water region (or the region lying eastward of 

 the granite range), in which marl may not be found sufficiently 

 accessible for profitable use. For example : from a mile south of 

 Petersburg, along the line of the railway to the Roanoke, no marl 

 had been found either by the excavations for the road, or in the 

 much deeper wells dug long before in the vicinity of the route. 

 The well for the water-station nine miles from Petersburg did not 

 at all times supply enough water for the engines, and it was deter- 

 mined to dig one deep enough for that purpose. Disregarding the 

 small veins of water usually reached at less than 20 feet, the 

 digging was sunk to 50 feet, when marl was reached. Its quality 

 at top was rather poor ; but it became more and more rich, as well 

 as of firmer consistence (though never very hard), until the well 

 had been sunk to 80 feet, without reaching the bottom of the 

 marl, or finding any other vein of water. The lower part of this 

 marl was from eighty to ninety per cent, of carbonate of lime, as I 

 found by several analyses. It would have served to make good 

 lime, by burning, for cement or for manure, to be transported to 

 a distance on the railway ; besides being of more value to be used 

 unprepared to enrich the nearer land. Though covered by fifty 

 feet of earth, and the excavation impeded by the water from above, 

 this marl might have been profitably raised eighty feet, or as much 

 lower as the bed may extend. And so firm was its texture, that 

 the excavation might have been safely enlarged gradually as it was 

 deepened, as is done in the chalk-pits of England, so that the 

 digging should form a hollow cone, communicating from its apex 

 by the narrower cylindrical well through the fifty feet of earth 

 above to the surface. Thus, though the earth might have been 

 twice the thickness of the marl below, the greater diameter of ex- 

 cavation in the latter would have furnished much the greater quan- 

 tity of contents. Of this most valuable deposit, found in a region 

 before supposed destitute, and where its transportation to a long 

 line of destitute land was so convenient, no use has been made, 

 except of the quantity necessarily drawn up in digging this well. 

 And this means for enriching the undertaker, and fertilizing a vast 

 extent of surface of acid and poor land, will probably remain totally 

 neglected for the next fifty years. It is most probable that this 

 same thick and rich body of marl may be found at many miles' 

 distance on the line of railroad, and indeed wherever the surface 

 is in the same position relative to the granite range. (1842.) 



After marl has been found, whether by natural exposure or by 

 boring, it may still be difficult to distinguish it by the eye. If 

 fossil sea-shells are intermixed, and enough preserved in form to be 

 distinguishable, that is certain proof that the object sought has 



