^4 Essay on the Transition Rocks of the Cataraqui. 



Art. VIII. — Continuation of the Essay on the Transition Rocks of 

 the Cataraqui; by Capt. R. H. Bonnycastle, R. E. Up. Can. 

 (With figures — see the plate.) 



(Continued from Vol. XVIII, p. 104.) 



In proceeding eastward from the hill on which the curious tablets 

 above mentioned laj, like monumental records of animal races, whose 

 very existence would have been otherwise unknown, we pass over a 

 rough and uneven portion of the limestone country, where Earth- 

 quake appears to have partially exerted his giant power, and here is 

 discovered another singular and, as far as I am avs^are, unusual dispo- 

 sition of the calcareous rock. 



In the upper parts of the denuded beds, at certain points, as, for 

 instance, at si short distance in front of the road which crosses Point 

 Henry and at about one hundred and ten feet above the level of the 

 lake, where the layers have been disunited in searching for quarries, 

 a sort of faintly marked Ludus Helmontii, resolvable into a series 

 of finely graven wavy septaria, may be discovered on the flat and 

 weather-worn surfaces. 



These septarian lines, depicted thus on the tabular surfaces, are 

 surrounded by undulations, through which the stone is roughened 

 into a continuity of little knobs and cups, which a smart blow causes 

 to separate along the tortuous lines of the wavy septae, and discloses 

 a beautiful series of extremely delicate and minute columns, which 

 penetrate, in some instances five or six inches, into the layer of stone, 

 but more commonly only to the depth of ha,lf an inch or an inch. 



These acicular columns, or rather fiutings, are perpendicular to 

 the plane of the bed, and are generally terminated by a folding, as it 

 were, of their inferior extremities into a crater, ' whilst however, the 

 needles or fibres retain their parallelism, which they, invariably, pre- 

 serve throughout their vertical position. The crater, or cup-shaped 

 termination is thicker as its hemisphere approaches its lowest part, 

 whilst the hair-like prisms are every where else very thin, and indeed, 

 are a mere coating to the limestone they envelope. These flutings 

 are sometimes very deeply channeled, at others the specimen has 

 the outward look of an imperfect prism or cylinder.* 



* I have one large piece, of which a drawing is subjoined, (.^ee the plate,) which 

 when reversed, or placed on tlic natural flat surface, originally uppermost, looks like 

 two fluted towers, joined by a fluted barbican, and crowned by rounded roofs; the total 

 height i,s about three inches, the total length near five and the thickne.5S nearly two. 



