IN GLEN TILT. 323 



strata lying over the red sienite, of which a large mass follows 

 to the eastward. The strata have somewhat of the characters of 

 compact dolomite, and probably consist of this substance inti- 

 mately blended with a large proportion of others. Their 

 stretch is about N. 7c» E., and their dip southerly at a consi- 

 derable angle. Near the junction there are portions of the 

 strata included in the sienite, so a to produce some resem* 

 blance to an interstratification of the two substances. 



50. From hence rocks of the sienite appear on this side also, 

 near the water and beneath it, through the rest of the reach, 

 and forty or fifty yards farther. For about sixty yards, and to 

 a point marked 5 in the plan, a junction of the strata and the 

 sienite may be accurately traced in the bank ; beyond that, the 

 whole rock is of sienite. The strata, at the junction, lie over 

 the sienite, dipping into the bank at an angle of from 30° to 

 50°. In some places they are bent. No veins of the sienite 

 are here seen passing into the strata, and in the body of the 

 strata I observed only one small obscure vein of sienite, or per- 

 haps red felspar. 



51. But in some of the rocks along the northern bank, there 

 are junctions of strata and the sienite, attended with different 

 circumstances. We found there no continuous strata of 

 great extent, but various detached masses, consisting of granu- 

 lar limestone, gneiss, mica-slate, and hornblende-slate. These 

 masses lie very irregularly ; some of them are imbedded in the 

 sienite, and others intersected by veins of it. Two instances 

 deserve to be more particularly described. 



52. One occurs in some strata of mica-slate, near the edge 

 of the water, in a spot referred to by the figure 6. In. stretch 

 and dip, these were judged to agree nearly with the strata ly- 

 ing under the sienitic gneiss lower down ; and this makes their 

 stretch to be N. from 80° to 90° E., and their dip southerly 



about 



