284 BOARD OF AGRICULTURE. 



portion of the Silurian system, and more probably the Upper than 

 the Lower Silurian. On Moosehead Lake there is very little dif- 

 ference lithologically between the mica schists at the south end of 

 the lake, and the schistose sandstones at Soccatean Point contain- 

 ing Oriskany fossils. And as Mr. Hodges, Jackson's Assistant, 

 found "madrepores" at the base of Squaw mountain, which are 

 without doubt the common Favosite coral of the Upper Silurian, 

 we have some evidence upon which to tound our conjecture of the 

 Silurian age of these slates and schists. 



Our observations of the dip at the Forks are scanty. East of 

 the Forks Hotel there is a long bluff of slates interstratified with 

 limestone, dipping 40° S. E. The rocks alternate in great measure, 

 yet occasionally the limestone is three or four feet thick. Dr. 

 Jackson analyzed this limestone and found it to contain Carbonate 

 of lime 50.0, Silica 27.0, Magnesia 9.0, Alumina 8.4, Carbonate of 

 iron 2.8, and Oxides of iron and manganese 2.4; total, 99.6, He 

 recommended that this rock be burnt at a red heat, then pulverized 

 and mixed with fifteen per cent, of clay and ten of manganese, so as 

 to form a hydraulic cement equal in value to that imported from 

 England. We know not whether this anticipation has ever been 

 realized. This limestone is more or less abundant in the ledges on 

 both sides of the river, so much so that it must form a part of the 

 lithological name of the formation, if it shall be found to occur over 

 a wide region. The dip is higher in going east from the bluff, and 

 the formation extends certainly to Moxie Falls. 



On the west side of the Kennebec river we found a great many 

 ledges of slate with a high south-easterly dip, as we supposed at 

 first ; but we soon discovered a ledge showing this view to be 

 erroneous. We found traces of a gentle dip, say 20°, to the north- 

 east, which we suppose, to be the true one, while the very promi- 

 nent highly-inclined planes are those of cleavage. To illustrate 

 this fact, we introduce here in Fig. 45, a sketch of a small curve 

 of the strata cutting across the cleavage planes. It is a sharp 

 synclinal fold. There are two beds of limestone, the upper two, 

 and the lower one foot thick, found interstratified with slates. 

 Onl}' the latter have planes of cleavage, and these are represented by 

 the finer lines inclined to the right (south-east) at a high angle, while 

 the two beds of limestone rest each upon a bed of slate. Several 

 very crooked veins of white quartz occur in the upper limestone 

 bed, while the layers of limestone are not very much contorted. 



