44 Notices respecting New Booh. 



way stretching, a ponderous and frangible body, is to produce 

 a division of its parts in such order and direction as its varying 

 strength and tenacity dictates; the fractured parts taking their 

 places, according to their magnitude or gravity, or the disposition 

 of those which support them. This irregular fracture, alternate ele- 

 vation and subsidence, and settling of parts thus disturbed, are well 

 exemplified in the familiar operation of the heaving of the spade in 

 digging. If the earth be tenacious and the action steady, it tears 

 with such a divergence of the principal rents as will be here de- 

 scribed ; and the more friable parts are seen dropping in in such 

 a way, and in such proportion, as the moving power dictates, and 

 their structure allows. If another illustration were necessary, it 

 might be found in what we observe in the elevation and cracking of 

 the flour which covers the fermenting nucleus in a baker's trough. 



" Where opportunities occur for tracing these appearances in the 

 weald, they are found to be in perfect accordance with this theory. 

 These opportunities present themselves frequently in the clay 

 districts; but they are more distinctly traceable in the stony, in the 

 dip and variable lateral bearings of the several masses. It may 

 be safely said, that undulation, at the time of deposit, had very lit- 

 tle share in these phaenomena, or in the construction of the hills 

 and valleys of these districts. Every variation in dip or lateral 

 bearing has its commencement in a fracture, or if the displacement 

 be moderate, such a contortion as would be produced by the gra- 

 vitation of bodies like these, moving under great superincumbent 

 and lateral pressure. 



" The general dip of the chalk-hills is southward, but the lateral 

 bearings of the several masses are variable*, and the inclination 

 also different in different localities. Next to these succeed the more 

 broken strata of the green-sand ; and lastly, the smaller lacerations 

 of the wealden formation, the widely spreading transverse fissures 

 of which concur to produce the effect of longitudinal ones over all 

 the convexity of the ' forest ridge.' But it is not to be under- 

 stood, that there is any difference in the general disposition of all 

 these parts. The convexity extends from the bottom of the Eng- 

 lish Channel to the bottom of what is called the London basin. 

 This convexity may be likened to a dome, and the loss of a part of 

 the crown of the dome is the weald vacuity. In other words, the 

 commencement of each basin is in the anticlinal line of the weald 

 valley. From this point, all the strata begin to slope. Both basins, 

 therefore, may be said to be entire in a part of the wealden, al- 

 though they have lost a part of their rims in the chalk and the 

 glauconite. 



* " In ordinary geological language, there is not sufficient precision used 

 in these terms ; and lateral bearings are confounded with the dip, which 

 should express the backward and downward inclination only. Thus, of the 

 strata in question, sometimes we are told that they dip S.E., sometimes 

 S.W. The fact is, that they all dip to the south, generally speaking, but 

 the obliquity of the plane, or lateral bearing of the different masses, is some- 

 times east and sometimes west." 



" The 



