THE HUILDINC OK AN ISLAXIJ. 1/ 



and like places, and nii^ht easily mislead an inexperienced observer to record 

 it as true stratification. After, however, he had seen thi' lines follow the surface, 

 even on tht' slojies of a hill on both sides, he would suspect it, and the t'xanii- 

 nation of a section like that at Cane (iarden would make the whole matter 

 clear. It has already been noted that the Cane Garden cliffs present alterna- 

 tions in the beds; in some of the layers we have the sea-sand with its minute 

 shells and spines of sea-eggs nearly as the whole was deposited; in others, 

 alternating with these, we see that the rocks have been hardened, while the 

 corals which they had contained are indicated by hollows only, the sid)stance 

 of them having been dissoKed away. If we ask why there should be these 

 alternations in the strata, it is only possible to reply in a general way that the 

 conditions must have been continuallv changing, a general statement which 

 admits of clear illustration, however, by taking a case from our harbour. Just 

 inside the reef itself several shoals have been formed, and some of these consist, 

 on the top at least, of finger-shaped corals, some alive but most of them dead. 

 It is plain that this layer of corals must rest on something else (sand, for 

 example), and if the surface conditions should later be changed the coral layer 

 would in turn be covered by a different accumulation. Now in the limestone 

 rocks at Evening Hill, west of Christiansted. a similar accumulation of finger- 

 shaped corals in beds mav be found, so that we have the ancient accumulation 

 and the modern accumulation not far from each other, the latter enlightening 

 us as to the origin of the former.* We may say then, that the hnver part of 

 the Cane Garden section, read in the light of an illustration from elsewdiere, 

 gives us a good deal of the history of our limestone formation, white the upper 

 part, as shown above, throws light on recent changes which io a large extent 

 obliterate the earlier record. 



Thinning Out. 



In connection with the above a condition which mav sometimes be seen in 

 a layer in a (|uarrv or roadside cutting should be mentioned. It is sometimes 

 noticeable that a layer does not continue through the whole length of the cut- 

 ting, but becomes gradually thinner and finally disappears, leaving the layers 

 below and above it to touch each other. An example may be seen at the cutting 

 to the south of the road at Anna's Hope, where a bed of fine gravel //i/ns out in 

 this way towards the southwest. If we could see the whole of our limestone 

 beds it is likelv indeed that most of them would be found to thin out before 

 they had extended over anv large area; that we do not more often see it arises 

 from the beds being generally exposed for rather short lengths. 



* It may be noted in passing that these Evening Hill rocks are of special interest, on account of their 

 containing the largest species of foraminiferous shell found on the island, and found, as far as the pre.sent 

 writer is aware, at this spot only. The shell commonly measures about a quarter of an inch acrcss, is round 

 and flat, with a bulge in the middle.' It contains a great number of very small oblong chambersor rather 

 chamberlets, which make it an interesting shell to examine, and it has a special scientific interest in con- 

 nection with the determination of the age of our limestone rocks in the world's geological history. 



