SKY. GEOLOGY. RED SANDSTONE. 311 



spot, these irregularities may perhaps safely be attributed 

 to their presence. Still tracing the beds to the south- 

 ward as far as Daalvil we find no material alteration ; 

 nor does any reason appear for suspecting that we have 

 quitted the sandstone series, till we arrive at that point 

 beyond it where a portion of trap is laid down in the 

 accompanying map. I shall describe this portion here, 

 on account of its, minuteness, instead of deferring the 

 account to its systematic place. 



It forms a bed distinctly overlying the sandstone, of 

 an irregularly columnar structure with a schistose tend- 

 ency and a slightly porphyritic character; the laminar 

 direction being parallel to the axes of the columns, 

 whereas in the claystone porphyry of Arran, it lies at right 

 angles to them. The space it occupies appears to extend 

 about a mile. There occurs under it a single insulated 

 mass of conglomerate, consisting of a calcareous basis 

 with imbedded fragments of red sandstone, sometimes 

 angular at others rounded. The want of connexion be- 

 tween this mass and the accompanying strata, and the 

 small space which it occupies, render it difficult to under- 

 stand its relation to the sandstone ; but it is probably 

 the sole remaining part of a more extensive tract once 

 continuous with the leading mass of secondary rocks that 

 will be described hereafter. 



Where this trap ceases, the sandstone series is again 

 found, in no way altered, and from this place throughout 

 all the remaining space it presents all the members formerly 

 described except the white quartz ; namely, the hard blue 

 rock, the grey varieties, the common red sandstone, and 

 the schist, in endless alternations. The dip still con- 

 tinues easterly, but the regularity which ceased at Dun- 

 scaich is never recovered ; the beds undergoing undulations 

 which at length increase to contortions and flexures such 

 as are of common occurrence in micaceous schist and 

 gneiss. Approaching still nearer to the point of Sleat, 

 the alternations become so frequent that the laminse 



