1835.] 



FARMERS' REGISTER. 



667 



the green sand abounds, is quite as beneficial as 

 the marl itself! Furl her observations respecting 

 the green sand will be given in treating of the 

 Eocene marls, of which it constitutes a very im- 

 portant ingredient. 



Sulphate of Iron and Sulphur. — In some parts 

 of the Miocene district, there occur beds of clay 

 more or less sandy, and usually of a dark color, 

 containing these substances in a minute but still 

 appreciable quantity. Such matter, there is rea- 

 son to believe would not in general prove direct- 

 ly beneficial to the soil. The former has been 

 thought positively detrimental to vegetation, and 

 certainly when applied in considerable quantity, 

 this is its effect. What agency it might exert in a 

 more diluted state, and mingled with other matter, 

 we are without the means of determining. Pro- 

 bably under such circumstances it might operate 

 as a stimulant: and thus contribute to the growth. 

 The same doubts are also applicable to the other 

 substance above named. Yet in some well au- 

 thenticated cases, the action of these copperas and 

 sulphur clays has been Ibund strikingly beneficial. 

 In these instances, however, it would seem that 

 much if not all the benefit was produced by the 

 effectual protection which even minute quantities 

 of these substances, especially the latter, afford 

 against the attacks of insects. In a cotton field 

 in which all the alternate rows were lightly sprink- 

 led with earth of this description, the plants so 

 treated grew up vigorous and healthy, while the 

 others became sickly and were nearly devoured 

 by insects. Much careful observation is required 

 to determine the kind and mode of influence which 

 these substances exert, and it would be premature, 

 in our present ignorance of the matter, to assert 

 any convictions on the subject. The presence of 

 the former of these ingredients, if not recognized 

 by the copperas flavor, will be readily discovered 

 by steeping the earth in water, decanting the clear 

 liquid, boiling il down to a small volume, and 

 then adding tincture of galls or prussiate of potash. 

 A black or brown color with the former, or a blue 

 one with the latter, would indicate its presence. 

 The experiment, however, should be made in a 

 glass or china vessel. The sulphur becomes 

 manifest, to the smell when the clay is heated, and 

 even at. ordinary temperatures its peculiar odor 

 may often be perceived. 



Eocene marl district. 



As already indicated, the extent, and boundaries 

 of this interesting portion of eastern Virginia are 

 as yet in a great depree matters of conjecture. 

 The discovery of an Eocene deposite in the state 

 first announced by me about eighteen months aw, 

 in a communication to the Farmers' Register, has 

 been followed up by a minute personal examination 

 of some parts of the district in which it occur?, 

 more especially on the James river and Pamun- 

 key. Its existence on the Rappahannock and 

 Potomac has also been ascertained, and speci- 

 mens have been obtained from a number of inter- 

 mediate points. With regard to the region south 

 of the James River, i hough facts have been pro- 

 cured which show conclusively that the deposite 

 continues to the southern boundaries of the state, 

 time has not admitted of such an investigation as 

 would be necessary in defining its extent. A reg- 

 ularly continuing line of observations on the Pa- 



munkey river, commencing below the point at 

 which the deposite appears above the water's edge, 

 and extending up the river to the junction of the 

 North and South Anna, where it terminates, has 

 served to develope the arrangement and compo- 

 sition of the strata, and to determine the width of 

 this portion of the formation. An inspection of 

 the most important Eocene localities on the James 

 River has also contributed many interesting and 

 valuable tacts, while the Rappahannock and Po- 

 tomac, its western limits, have been determined 

 with as much accuracy as could be attained by 

 transient observations directed only to a few local- 

 ities. 



Wherever observed, the arrangement of the 

 beds of the Eocene and the minerals and fossils 

 contained in them, have been found strikingly 

 alike, and hence the description of any transverse 

 line of the formation may be regarded as convey- 

 ing a just representation of its character through- 

 out. At the same time, however, it is by no 

 means to be assumed, that in all localities the 

 same arrangment or composition of the strata 

 must necessarily exist; for within a short distance 

 in observations already made, considerable diver- 

 sities have been observed to exist. But there can 

 be little doubt that the general order of the strata 

 already remarked, as well as the character of 1 he 

 fossils which they contain, will present much uni- 

 formity whenever the formation may be discovered 

 within the limits of the state. 



The existence of Miocene strata over the Eo- 

 cene, has been referred to under a former head, 

 and some account of this more recent overlying 

 deposite within the district of which we are now 

 treating, may, with propriety, be prefixed to thj 

 description of the Eocene itself 



Of the Miocene which overlies the Eocene. 



Westward of the limits of the Miocene pre- 

 viously defined, the general level of the country 

 continues gradually to rise. A surface more gene- 

 rally undulating, and strewed with water-worn 

 fragments of stone, sometimes of considerable 

 size, marks our approach to the region of bills 

 and rocks, whence these memorials of the destruc- 

 tive lories of a former period have been derived. 

 The superficial strata in the western portion of 

 this district is generally a coarse sand or gravel, 

 ofien containing large masses of rounded sand- 

 stone and other rocks, of which the parent strata 

 are generally to be found at no remote distance to 

 the northwest. An inspeciion of these pebbles i3 

 sufficient to show, that in many, if not nearly all 

 cases, they are derived from the grits and sand- 

 stones with which the bituminous coal of eastern 

 Virginia is associated, while from the similar na- 

 ture of the sand and gravel in which they are 

 embedded, we are entitled to conclude, that at 

 least in part, they also refer themselves to the 

 same reffion for their origin. In the hills at and 

 .below Richmond, and in many other places, these 

 bel^s of gravel have considerable depth, and pre- 

 sent a structure at once curious and instructive. 

 A series of strata at these places, in some of 

 which the pebbles are disposed in horizontal lines; 

 in otherc in lines oblique, but still generally paral- 

 lel, inclining downwards to various points in the 

 differenttlayers, give striking evidence of the 

 agency of those diluvial and oceanic currents, of 



