ON THE ERRATIC BLOCiS OF ENGLAND, WALES, AND IRELAND. 103 



(9) No. 98— Ingleby Mill Dam; hard, sabangular ; 13x12x6 in. 

 No. 158 — Ingleby Mill Dam ; angular; ? x 7 x5 in. ' Felsite or porphy- 

 rite (Bonney). These blocks may not improbably have been derived 

 from the quartz-felsite of St. John's Vale, Cumberland. 



(10) No. 93 — Ingleby Mill Dam; sabangular; 8x4x3 in. 



(11) No. 125 — Ingleby Mill Dam ; sabangular; 17x8x? in. ' Por- 

 phyrite — old andesite (Cheviot?)' (Bonney). ' Possibly from the Che- 

 viots, but not a common type there, and should think more probably from 

 some of the porphyritic areas in the S. of Scotland ' (Clough). No. 138 

 — Ingleby Mill Dam; moderately rounded; 24 x 15 X Pin. No. 139 — 

 Ingleby Mill Dam ; subangular ; 21 x 18 x 10 in. The above are some of 

 the largest of these common blocks which so strongly characterise oar 

 local drift. 



(18) No. 839 — On right bank of stream below Ingleby Mill Dam ; 

 snbangular; 16x?xl4in. ' Porphyrite — probably an old andesite ' 

 (Bonney). ' Very like some of the upper Old Red traps of the neigh- 

 bourhood of Kelso. I have also noticed these rocks mixed with Cheviot 

 rocks in considerable quantities in Bridlington Bay boulders ' (Clough). 



(14) No. 2.32— Ingleby Mill Dam; angular; 8x7x5 in. 'Might 

 well be from the Lower Old Red porphyritic district of the Cheviot Hills ' 

 (Clough). 



(15) No. 275 — In Mr. Gill's field, Ingleby ; subangnlar ; smoothed ; 

 4 X 8 x 6 in. ' Felsite or porphyrite — Scotch ' (Bonney). 



(16) No. 303 — In stream below Ingleby Mill Dam; subangular; 

 10 X 6 X 6 in. ' Hornblendic porphyrite — S. Scotland ' (Bonney). ' Not 

 unlike portions of the lowest of the porphyritic flows at the head of 

 Coquetdale, Cheviot Hills ' (Clough). 



(17) No. 319 — -In stream near Mr. H. Bainbridge's farm, Greenhow ; 

 rounded ; 21 X 17 X 14 in. ' Hornblendic felsite or porphyrite ' (Bonney). 

 ' Very like some igneous masses in the Highlands near the head of Loch 

 Katrine, Loch Lomond, &c.' (Clough). 



(18) The largest of these is No. 302. In stream below Ingleby Mill 

 Dam; subangular; 17x10x6 in. 



(21) As the Cleveland Dyke at its nearest point, near the village of 

 Great Ayton, is distant only some four miles from the present position of 

 the boulders to which these notes refer, and as the ice-sheet must have 

 ploughed across it almost at right angles in the immediate direction of 

 our locality, we should naturally expect to find what, in point of fact, we 

 do find — numerous angular and subangular fragments derived from it, 

 intermixed with the other boulders. The ' Whinstone,' as it is locally 

 termed, is described in the memoir of the Geological Survey relating to 

 the district as ' a bluish-grey augite-andesite, consisting of a ground mass 

 apparently made up of angitic and felsitic mattej', with small crystals of 

 felspar and augite. Scattered through this are glassy crystals of triclinic 

 felspar of much larger size, very distinctly visible to the unaided eye, 

 and which give the rock a distinctive character by which it can be easily 

 recognised.' As other dykes of a very similar character occur in the 

 direction from which the ice-sheet came, it is possible that one or two 

 from other sources may have been put down as from this source. The 

 largest measures 48x35x34 in. Others measure respectively 39 in., 

 33 in., 29 in., 28 in., 27 in. in their longest diameter. 



(22) No. 113 — Ingleby Mill Dam ; imperfectly rounded, with smooth 

 faces ; 11 x 8 x 6 in. 



