Yol. 69. J TWO DEEP BOKIXGS AT CALVERT STATION. 323' 



the depth of 4S0 feet, the shales are traversed by small joints, the 

 walls of which are stained a bright red. In some beds where no 

 joints are discernible, narrow dull red bands are to be seen on 

 the bedding-planes ; and these, together with blotches of a similar 

 colour, give a mottled appearance to the shales. 



Below this point for a distance of 13 feet the core showed a 

 series of soft dark-red and green beds, which at the depth of 490 

 feet yielded a fragment of Qlonograptus (?) ; but a systematic search 

 through the beds revealed the fact that the reddening of the shales 

 was not original. It was noticed that the colour was deeper and 

 richer in beds which were more micaceous. Specimens were also 

 obtained which showed that while some portions were red, other 

 parts were merely tinged, the central part being greenish grey, so 

 that there is no doubt that the beds are stained. An explanation 

 of the staining is obtained, if we suppose that rocks of Triassic age 

 had originally extended over the Palceozoic floor beyond Calvert. 



The band of red and green shales passed gradually downwards, 

 through a thin belt of greenish-grey shales, into dark-grey shales 

 which persisted to the bottom of the boring without any important 

 change of colour, except where the beds were altered by the contact 

 of the two small sills. Below the depth of 496 feet some few 

 bauds are highly micaceous, and some (but not all) of these bands 

 are fossiliferous ; on the other hand, fossils are not confined to 

 them. The lamination is, in general, very imperfect, the rock 

 splitting with an uneven or sub-conchoidal fracture ; but, at 

 frequent intervals, it splits with a perfection suggestive of slaty 

 cleavage. That this fissility is not slaty cleavage is shown by its 

 remaining parallel to the bedding as the dip varies (even in such 

 a kink as that mentioned below). The planes of fissility are, in 

 fact, slickensided surfaces due to differential movement along 

 certain bedding-planes. Occasionally they show striations, in 

 approximately the direction of dip ; at other times the surface is 

 uniformly polished ; and in yet other cases there are irregularities 

 that project above the general level, and take a high polish. In 

 some cases the gradation from an ordinary rough bedding-plane to 

 a highly slickensided surface can be traced within the sectional 

 area of the core : the most beautiful example of this was at 

 1135 feet, in which case the zones of increasing polish were not 

 parallel to the direction of dip, but to one of the joint-planes, at 

 an angle of about 25° to the direction of dip. The distance apart 

 of the slickensided bedding-planes varies from 1| or 2 inches to as 

 much as 8 inches, in the higher part of the boring ; but towards 

 the bottom they come much closer together, being sometimes less 

 than half an inch apart. Slickensides oblique to the bedding are 

 sometimes seen. 



The bedding-planes in the grey shales are occasionally covered 

 by thin films of yellow-brown calcite : either in a continuous sheet, 

 -or in scattered circular patches which present a deceptive resem- 

 blance to crinoid-ossicles. 



Cone-in-cone structure appears at several levels. In one case 



