6 SIDNEY POWERS 



have sunk or been carried down over 2,000 feet, and the Laurentian 

 fragments in the same breccia brought up over 2,500 feet. In the 

 La Trappe dike the movement in each direction was probably not 

 as great, but the distance from the Beekmantown down to the con- 

 tact of the Grenville and Laurentian must have been several thou- 

 sand feet. 



Marblehead, Massachusetts: At Marblehead, Massachusetts, 

 half-way between Peaches Point and Naugus Head, are a number 

 of dikes of pulaskite cutting an igneous complex. These dikes range 

 in width from a few inches to 50 feet. In many cases they appear 

 to follow the course of earlier diabase dikes, all stages being present, 

 from a network of pulaskite veins in a solid diabase dike to a shat- 

 ter breccia of diabase in pulaskite and finally to a band of schistose 

 streaks of diabase in the center of a broad dike of pulaskite, show- 

 ing the former position of a diabase dike. In one case there are 

 remnants of two such dikes in a wide pulaskite dike. The diabase 

 fragments are lenticular schistose bands, sometimes several inches 

 in width, in a coarse-grained pulaskite, which grows finer-grained 

 in the small tongues which permeate the diabase inclusions. The 

 dark constituents of the pulaskite appear to have been derived 

 largely from the absorbed diabase. The width of the original dikes 

 was from i to 3 feet. 



Southern Sweden: At Brevik and at Karlsham-n, southern 

 Sweden, diabase dikes filled with rounded inclusions occur. They 

 have been described by Hedstrom^ and Eichstadt^ on whose papers 

 the following description is based. Two of these dikes are known, 

 being mapped on the Eskjo and Karlshamn sheets of the Swedish 

 Geological Survey. 



The dike at Karlshamn is 3 miles long and in places several 

 hundred feet wide. The inclusions are all on the west side of the 

 dike and consist wholly of quartzite and quartzitic sandstone. 

 Cataclastic structure is characteristic of all the inclusions, but this 

 texture was caused by metamorphism before the quartzites were 



' "The Pebble-Diabase of Brevik," Eleventh Internat. Geol. Cong., Guide Book 18, 

 1907, pp. 47-51- 



= "0m quartsit-diabas-konglomeratet i Smaland och Skane," Sveriges Geol. 

 Unters., Ser. c, No. 74, 1885. 



