East Haven-JBranford Region. 373 



N. 45° E., its dip 60° E. Thirty feet southwest of this point 

 the trap lies upon the edges of the upturned strata of sand- 

 stone, forming the contact-breccia from which thin section 

 No. 15 was made. In the old quarry east of the road the east- 

 ern sandstone has a westward dip. The o line of contact show- 

 ing the gradual overthrow of the dip may be traced from the 

 road into the quarry. North-northeast of this old quarry and 

 nearly half a mile distant on another road much coarse, hard, 

 dark-red sandstone is exposed, having its strike N. 45° E. and 

 its dip 40° E. This exposure is just west of the southern end 

 of the last member of the second eastern range of trap ridges. 

 Contact phenomena. — Contact with the underlying sand- 

 stone. The thin sections already mentioned as from con- 

 tacts between the trap and the sandstone, when examined 

 under the microscope, show no peculiar character that can 

 surely be assigned to the heated state of the trap at the 

 time of its rising. In No. 21a, which is from the contact 

 with the underlying sandstone in the railroad cut through 

 Pond Rock, the line of contact is strongly marked by an almost 

 black band of iron-stained trap. The trap and sandstone seem 

 to be cemented by the Fe 2 O s rather than by calcite, which 

 appears as amygdules in the trap. — Contact with the overlying 

 sandstone. No. 18, from the southern slope of the northern 

 hook of the same ridge, shows this contact. The trap is rather 

 uniformly stained with Fe 2 3 , but there is no band characteristic 

 of the contact, as in the slide just described. In the thin sec- 

 tion some small inclusions of trap appear in the sandstone near 

 the contact, but they are irregular in outline and show no signs 

 of having been at all water-worn before they were surrounded 

 by the sandstone. On the other hand particles of quartz, 

 orthoclase and mica are isolated in the trap near the contact. 

 No. 15, from the contact-breccia already described as occurring 

 on the east side of the second eastern trap range, shows small 

 angular masses of trap which appear to have been rolled up in 

 a soft sandy shale and consolidated by Fe 2 3 . There are iso- 

 lated inclusions of the shale in the trap. Hand specimens 

 from the same locality show fragments of sandstone intimately 

 mixed with the fragments of trap. This slide and No. 18 

 show a peculiar arrangement of the feldspar crystals in feathery 

 aggregates. These tufts are most noticeable at the contact, 

 but they are not confined to this position, and the ordinary 

 lath-shaped crystals alternate with these aggregates at the con- 

 tact, while some of the fragments in No. 15 do not show the 

 structure at all. The tufts show only aggregate polarization. 

 That they are composed of altered feldspar seems to be true 

 from the fact that they are seen occasionally to grade off into 

 the common lath-shaped crystals of plagioclase. They do not 



