306 Dr. John T. Plummer on the 



6. Siliceous limestone. Not very uncommon. 



7. Silicicalce, (Cieaveland.) Rare. 



8. Saccharoid block, with sulphur yellow stains and encrinites, 

 and large, somewhat stellar impressions. 



Where are the localities that furnished all this variety of bowl- 

 ders ? Were the masses transported to this place by direct, de- 

 flected, or converging currents? How do the bowlders remotely 

 east, west, and south of Richmond, differ from those in the above 

 catalogue? I hope that increased or continued attention to these 

 denizen rocks, will enable us ere long to answer these questions 

 satisfactorily. A strict examination in numerous districts, would 

 guide the inquirer into this subject with a great degree of pre- 

 cision. If the salient point of the rock containing Cytherinae 

 is ascertained, and fragments are found strewed in diminishing 

 quantities and lessening sizes from that point to Wayne County, 

 so that the last bowlder falls at Richmond, what forbids, with 

 the aid of collateral evidence, a close approximation to the nature 

 of the force producing the distribution, the direction, height and 

 width of its action, its violence, and its velocity ? In some dis- 

 tricts, serpentine is found out of place ; it will be perceived by 

 the foregoing enumeration, that none has been found here : where 

 shall the limits of its dispersion be drawn ? The same question 

 may be asked concerning every other bowlder ; and when cor- 

 rect answers shall have been obtained, a highly interesting and 

 comprehensive map may be constructed, from which the geolo- 

 gist may safely derive the elements of a theory. 



Water. — Springs and oozing banks are common all over this 

 section of country, and water may be obtained every where at 

 depths varying from two to thirty feet ; the average depth of 

 our wells being twelve to sixteen feet. The water is cold and 

 clear, and is acceptable to those who do not prefer soft water. 

 Being highly charged with carbonate of lime, our tea-kettles 

 are constantly encrusted with a calcareous deposit, which re- 

 quires occasional removal to prevent it from entirely obstructing 

 the spout. Similar incrustations take place in the open air on 

 stones, sticks, and earth, and over whatever the water runs, 

 whenever circumstances are favorable to the deposition of lime. 

 The fissures in our blue limestone are sometimes lined with a 

 tolerably pure alabaster J but the inlets to the water having been 

 closed long since by the calcareous deposition, these crevices are 



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