Notice of a Scientific Expedition. 351 



the same structure may be seen at the Digby light house. The fu- 

 sion seems not to have been sufficient to produce a freedom of mo- 

 tion among the particles of composition. It is well known that a 

 concretionary structure is sometimes given to hearth stones, which 

 have long been subjected to heat. So far as this fact goes, it may be 

 applied as an explanation of the kind of structure here spoken of. 

 Different degrees of heat, we believe, we are warranted in saying, 

 have acted on the greenstone of Nova Scotia. Sometimes it is per- 

 fectly columnar, in masses composed of separate columns piled up 

 one above another ; again, the same structure is distinct, but there 

 is no separation of the mass into separate columns, there is still an 

 adherence of their sides. It would be interesting to describe all the 

 appearances the trap assumes, but the field is too wide for us at 

 present. We wish others to go and see for themselves. The form- 

 ation is on a large scale, — it is grandly exposed and laid open to 

 view, — frequently the whole thickness of the amygdaloid and green- 

 stone, is raised up for inspection, and every year they scatter their 

 treasures profusely on the shore. It is fitted, therefore, by nature 

 to instruct and enlighten, and to open to us the great mysteries which 

 shroud the origin of these rocks. In conclusion, we ask the indul- 

 gence of the reader, while we make a ievi remarks on two or three 

 topics which have been briefly alluded to or connected with subjects 

 discussed in the preceding pages. 



1st. Geologists as a body, seem to have overlooked too muchy 

 those causes now in operation, which tend to modify the surface of 

 the globe. It may never be proved absolutely, that the earth has 

 been brought into its present state by the slow operations of agents 

 now at work, although these very agents working at their present 

 slow rate, have done much to alter the earth's surface. But does it 

 contradict either experience or observation, or both, to assert, that 

 a given agent accomplished more formerly than now, although it 

 operated with the same energy only. If an extensive island should 

 be thrown up from the deep, would not the first rain which fell upon 

 it, wash down more sediment to the sea than the same quantity of 

 falling water afterwards. May we not suppose that the upper layers 

 of rocks were softer and more easily abraded than the deeper ones ? 

 if so, they must have been more deeply worn and furrowed soon 

 after their elevation than in these days. If the reasoning is correct, 

 then we have furnished a greater quantity of detritus in early times 

 for the formation of transition, secondary and tertiary deposits. With 



