1821.] situated at Calder Side. 25 



into each other are worn away, as it were, at their centres into 

 the form represented at fig. 2, and fig. 1, section of the perforated 

 stratum. 



The hollow parts of the stratum are filled with a fine earth; 

 which has much resemblance to Armenian bole, and is coloured 

 with iron, being stained and streaked, of various tints of red, 

 orange, and yellow. This fine earth is constantly moist, and as 

 soon as it is exposed to the air, it becomes covered with a luxu- 

 riant coating of vegetation, consisting of a minute species of 

 conferva, whose thin roots, resembhng the fibres of a spider?* 

 web, penetrate it in all directions. Such an appearance would 

 have afforded matter of speculation to Duhamel and Henkel, and 

 might have assisted these philosophers in their researches rela- 

 tive to what has been termed the equivocal generation of plants.* 

 Have the diminutive seeds of these confervse remained concealed 

 for ages, locked up in the interior of a stratum of limestone, and 

 bwried beneath various strata of schistus and ironstone, and still 

 retained the power of germinating as soon as exposed to the air 

 of the atmosphere ? 



The upper and under superficies of the perforated stratum are 

 thickly covered with petrifactions consisting of a lesser variety 

 of entrochi, and a quantity of shells of the genus ostrea, the 

 substance of which does not appear to have been much changed 

 by the petrifying process. At the time when these shells 

 became imbedded in their present situation, the animal inhabi- 

 ting them could not have been ahve, as tiie valves are all of 

 them found separate, and what is remarkable, those situated 

 both on the upper and under superficies of the stratum have the 

 interior superficies of the valve almost invariably turned towards 

 the stratum. In the body of the blocks only a few entrochi, 

 and none cf the bivalve shells occur. A few of the shells and 

 some of the entrochi coat the surface of the intersticial vacui- 

 ties. What a strange variety of causes must here have been 

 called into action to produce the effects to be observed here : 

 on the upper and under superficies of the stratum we have petri- 

 factions resembling each other in their nature. In what maybe 

 termed the body of the stratum, we entirely want the more 

 recent and perfect of these petrifactions ; viz. the bivalve shells, 

 and have only a few of the entrochi. 



The same law which seems first to have acted in the formation 

 of the perforated stratum seems also to have exerted its influence, 

 although only to a very limited extent, upon the superincumbent 

 strata of schistus and ironstone ; for these strata seem to show a 

 tendency to separate into somethiag of a crystalline structure, as 

 it were approaching to very imperfect basaltic columns in the 

 direction of the fines A B U, fig. 1. 



If we could suppose that previous to the blocks composing 



^ ♦ See Henkel's Flora Satumisans, chap. ii. p. 35 and 36. 



