US Scientific Intelligence* 



greatest breadth of the trunk of the larger tree was about one foot, and 

 it diminished from this very gradually for about fifteen feet, which is 

 the extreme length to which they have been uncovered. The stem of 

 the larger tree was divided transversely at nearly regular intervals of 

 about fourteen inches by a cleft or notch, which corresponded to a sim- 

 ilar ridge or prominence in the sandstone, both above and below. The 

 two trees are not in the same plane, as may be seen in the sketch 

 which correctly represents the smaller tree in the foreground as about 

 two feet below the larger and three feet distant from it. The cast or 

 impression of the larger tree gives its characters more distinctly than 

 the stem itself: and this impression also measures in diameter consid- 

 erably more than the trunk which it represents, showing that the latter 

 has shrunk from its original dimensions. 



The thickness of deposits over these trees is not more than six feet 

 of sandstone and the same amount of diluvium; but this gives us no 

 idea of the thickness which has undoubtedly been removed by denuda- 

 tion. A microscopical examination of specimens of the trunks of these 

 two trees has been kindly undertaken by my friend, Prof. J. W. Bailey 

 of West Point, who confirms the supposition that they were coniferous. 



No cones or leaves could be detected in this locality, nor had any 

 such, or in fact any other fossils, been obtained by the quarrymen, 

 although there is a tradition that many years since, trunks of trees 

 were found in a quarry near the present one. Mr. Manross has 

 made particular search here for footmarks similar to those found in 

 other parts of this deposit, but without success. By the zeal and good 

 management of this young gentleman, about four feet in length of 

 the larger tree was successfully removed with its corresponding cap- 

 ping of sandstone, and now forms one of the ornaments of the geolog- 

 ical collection of Yale College. The writer supposes that this is the 

 first instance in which the trunks of hard-wooded trees have been ob- 

 served in situ in the Connecticut sandstone. Fragments of agatized 

 wood have been found in Massachusetts by Prof. Hitchcock, and'in the 

 smaller secondary basin of Southbury, Ct., and large stems of reed-like 

 plants are found in the beds which furnish the fish at Middlefield in 



th Z S , a ^ e i f tate - B. SlLLIMAN, Jr. 



\ ale College Laboratory, June 1, 1847. 



7. Observation on the Basaltic Formation on the northern shore of 

 Lake Superior ; by T. R. Dutton, (communicated for this Journal.)^ 

 The display of igneous rocks on the north shore of Lake Superior is 

 one of great interest to the geologist, both on account of the variety of 

 the different formations, their relations to the adjacent slates, and the 

 fact that some of them are the repositories of copper and silver.— 

 Among these instructive rocks may be found, granite of a more recent 

 dale than the Devonian strata, sienite, porphyry, greenstone and trap, 

 both compact, amygdaloidal and basaltic. It is of the last-mentioned 

 formation that we now speak. 



The numerous islands which occupy the most northern part of the 

 lake are composed of trap and porphyry with underlying sandstone, 

 and must be considered as one of the most important parts of the met- 

 alliferous region of the northern shore. On the southern shore of 

 ktrapsoQ's Island and the southeastern of St. Ignace, the two largest of 



