270 Geology and Mineralogy of the 



jasper,* red, green, ash, and greenish brown and black, en 

 ther uniform, or in stripes and clouds. The first and last 

 of these species often run into each other. 



The greenstone conglomerates are also of three kinds — 

 that of quartz nodules, of the granitous compound, of the 

 " Serpent rock," and of greenstone nodules. 



Breccias of the same composition with these conglome- 

 rates are not uncommon. 



Near Colher's Harbour and on an islet near the Grand 

 Manitou a curious mineral occurs in rolled fragments of close 

 grained granite. 



It is in the form of octohedral crystals with rounded edg- 

 es—one specimen was found three inches in length and two 

 and a half in breadth. A section discovers the following 

 appearances. The external coating is a slender layer of 

 dark copper colored mica in promiscuously arranged frag- 

 ments, succeeded by an inner ring of a substance resem- 

 bling hornblende, which insensibly passes into a yellowish 

 green mass of fibres radiating from the centre of the crystal, 

 where, however they disappear in the form of a whitish 

 yellow powder. [See plate, fig. 4.] 



The organic remains of the limestone of St. Joseph in- 

 clude numerous and very extraordinary appearances similar 

 to what Dr. Lloyd of Oxford in his Ichnographia calls Al- 

 veoli — cylindrical tubes or cases, of various sizes — sometimes 

 giving off branches, — belemnites, coralites, impressions of 

 weeds, four species of entrocite, five of bivalves, trochites 

 and turbinites.f There are also, honey comb and chain 

 madrepores, and many singular impressions &ic. which are 

 perhaps non-descript; but no adequate idea can be formed 

 of them without accompanying sketches. 



Drawing No. 5, is one fourth of the size of a relic ta- 

 ken from a small island off the river Thessalon on the north 

 coast of Lake Huron. It was found imbedded in a large 

 fragment of limestone. The raised and more perfect por- 

 tion is elevated above the matrix, one and a half inches. 

 The mass separates into two parts in the fine of the delin- 



* In some rai'e examples, masses of greenstone accompany the jasper, in- 

 dicating the destruction of a greenstone, previous to the formation of the 

 jasper conglomerate. 



t The shells in Lake Huron, at present existing, are tellinites, nautilites, 

 cochlites, turbinites and various bivalves. 



