183G.] 



FARMERS' REGISTER 



627 



Now, since covering prevents running together 

 — and this injures the crop — it must be a good 

 thing to cover the soil against this bad effect of 

 beating rains. 



Secondly; covering is also a protection ngainst 

 the pressure of the hoof— and I would adJ, it is 

 injured more or less, in proportion to the quantity 

 of the litter — more in the spring and summer, than 

 in the fall; land newly turned out more than that 

 which has been resting; poor land more than rich; 

 old land more than newly cleared, as the roots in 

 the latter, prevent ihe effect. The truth of the 

 first proposition in this paragraph, will not he dis- 

 puted by any one — and the others are plain infer- 

 ences from the first. 



Thirdly; the moisture that constantly rises from 

 the pores of the earth, which i would call the 

 earth-sweat, is retained on its surface, by covering, 

 which prevents evaporation. This may be seen, 

 by putting down a plank upon the ground and let- 

 ting it remain but a short time. May not this per- 

 spiration of the earth contain something that con- 

 tributes to the growth or health of the plant? I 

 have observed that a very slight cracking over 

 with the hoe, so as merely to open the pores, pro- 

 duced fine effects. At any rate, (he retaining of 

 this moisture, by covering, keeps the skin of the 

 earth (if I may use the expression,) supple — and 

 plants, which resemble hair of the human body, 

 grow better. And observe, when the soil is made 

 close by heavy rains, the hoof, or any other cause, 

 it breaks up in clods, and a great part of the soil is 

 in an inactive state — and until they are pulver- 

 ized, remain dead capital. These clods have 

 often reminded me of the worthless and idle part 

 of the community, whose room would be better 

 than their company, unless they could, by some 

 pulverizing process, be brought to assimilate with 

 the active mass of our population. 



J. R. 



EXTRACTS FROM THE REPORT OF THE GE- 

 OLOGICAL RECONNOISSANCE OF THE STATE 

 OF VIRGINIA, MADE UNDER THE APPOINT- 

 MENT OF THE BOARD OF PUBLIC WORKS. 



By William B. Rogers, Professor of Natural Phi- 

 losophy in the University of Virginia. 



TERTIARY MARL REGION. 



The extensive area embraced in this division of 

 the state, though presenting comparatively little 

 diversity in external aspect, includes strata, which 

 bv their fossil contents, unequivocally refer them- 

 selves to two distinct geological periods, though 

 they are all without doubt comprised in the gen- 

 eral class of tertiary formations. Adopting the 

 names which have been recently applied in Europe 

 to parts of the tertiary series, to which the strata 

 referred to may he regarded as probably equivalent, 

 though without implying any conviction on our 

 part, that such equivalence is in general to be ex- 

 pected in the two continents, we shall indicate by 

 the term Miocene the. strata which occur in the 

 eastern and greater portion of this region, and 

 from which the ordinary shell marl is procured, 

 while we will apply the name Eocene to the depo- 

 eite of an older dale existing beneath and west of 

 the preceding, containing fossils of a different cha- 

 racter, and characterized by the prevalence in 



considerable proportion of the peculiar mineral 

 called green sand. 



The first of these, or the Miocene marl district, 

 comprehends all the area from the seaboard or 

 water boundary of the state on the east, to a line 

 conceived to be drawn through Northbury on the 

 Pamunkey, and Coggin's Point on the James Ri- 

 ver, in a direction nearly meridianal, but through 

 what precise points, further observations are ne- 

 cessary to determine. 



The other or Eocene marl district is compre- 

 hended between the imaginary line above, descri- 

 bed and another line passing from the mouth of 

 Acquia creek, through Wales, at the junction of 

 North and South Anna Rivers, and thence through 

 City Point, and further south in a direction not 

 yet precisely ascertained. Much of the district 

 here defined exhibits Miocene as well as Eocene 

 marl, the former being found either in highlands 

 remote from the rivers, or in the superior parts of 

 the river cliffs overlying the latter. The localities 

 above named were selected as points marking the 

 eastern boundary of this region, because at those 

 places the Eocene mail was observed to disap- 

 pear below the water line by a gentle dip to the 

 east. Its existence extensively beneath the Mio- 

 cene district may be looked upon as highly proba- 

 ble, though under what circumstances as to depth 

 and inclination of the beds, we have no positive 

 data to determine. 



Miocene marl district. 



In the most eastern portion of this division of 

 the tertiary, the general level of the surface is but 

 little elevated above tide. The country is a uni- 

 form flat, in some places subject, to be occasionally 

 overflowed. The rest of the region in question 

 has an elevation above tide, varying from twenty 

 to eighty feet. But few points, however, in the 

 district have a level corresponding to either of 

 these extremes, and by far the larger portion of 

 the surface preserves a height of from forty to 

 fifty feet. 



The surface of this more elevated portion, 

 though preserving a general level of remarkable 

 uniformity, is deeply channelled by innumerable 

 ravines. The smaller of these connect themselves 

 with large ones, and these with the wider and 

 deeper excavations forming the beds of the creeks 

 flowing into the neighboring rivers. The system 

 of ravines connected with one river are separated 

 by a narrow central tract from those connected 

 with the next, and in a general view of the dis- 

 trict, these systems present the appearance of 

 mere creeks or inlets subordinate to the great ri- 

 vers by which this region is broken into peninsu- 

 las. The number and extent of the large rivers 

 and the navigable streams of this portion of the 

 state, constitute the most inestimable of its natu- 

 ral advantages. The numerous creeks indenting 

 its peninsulas furnish the cheapest and readiest 

 avenues for a commerce which comes home to the 

 abodes even of its rural inhabitants, while its 

 surface scooped into ravines and its river cliffs 

 washed by the tides, disclose ihe rich materials 

 which are hereafter to bestow the highest rewards 

 upon its enterprise, by spreading fertility and 

 wealth to its remotest boundaries. 



The superficial stratum of the region we are de- 

 scribing i< an argillaceous and ferruginous sand of 



