ON THE EERATIC BLOCKS OF ENGLAND, WALES, AND IRELAND. 117 



pronounce, the aspect of the slide reminds me rather of a modified 

 crystalline rock than a partially crystallised sedimentary rock. It is 

 therefore now a kind of gneiss — what I should call a pressure-gneiss — 

 resulting from the modification of a crystalline rock -which may have 

 been a quartziferous mica-diorite. The fragmental aspect I attribute to 

 the result of pressure which has acted on a crystalline rock, and has been 

 followed by a certain amount of mineral change in the constituents ; of 

 course an arlcose of the right constituents might give a similar appear- 

 ance, but though the enlargement of fragments in situ is not unknown, it 

 is not common and generally occurs (except in the case of quartz) in 

 very ancient rocks only. The boulder must have had a long journey, for 

 such a rock could not be found in situ nearer than the Scotch Highlands 

 or Scandinavia.' 



BouLDEKS IN Essex, N.W. 



District on the Ordnance Map, Little Saling, N. ; Great "W'altham, S. ; 

 Braintree, E. ; Dunmow, W. ; centre of district, Felstead ; radius, from 

 five to six miles. 



Parish, Great Saling, 4 miles N.B. 



1. In Village Street — Boulder of dolerite, 33x29x18 in.; roughly 

 conical in shape ; rounded and polished ; no striae visible ; olivine-dolerite. 



2. In Newbister Lane — Three smaller boulders of dolerite, less than 

 12 in. in diameter ; one olivine dolerite, the others plagioclase-augite rock. 



Parish, Little Baling, 5 miles N.N.E. 



1. By the church wall — Boulder of calcareous sandstone, 61 X 34 x 17 in. ; 

 circumference, 158 in. ; pudding-shaped ; rather soft loose texture ; dark 

 grey colour ; fine-grained, with fragments of shells. 



2. At farm near the church — Boulder of sandstone, 45x35x24 in.; 

 oblong ; slightly striated ; rather soft ; fine-grained ; buff-coloured ; 

 containing many Belemnites ; quite lately dug out of the bottom of a 

 pond; Kellaways rock (?). Boulder of dolerite, 37 x30 xl8 in.; roughly 

 triangular ; distinctly striated on two surfaces with parallel striae ; rest 

 polished ; olivine-dolerite. 



3. At "Woolpits Farm — Boulder of dolei-ite, 39x38x19 in.; nearly 

 square ; distinctly striated and polished ; dug out of a ditch on the farm ; 

 plagioclase and augite ; no olivine. 



Parish, Stehhing, 3 miles N. 



1. At Mount Farm — Boulder of sandstone, 64 x 63 X 14 in. ; flat, sub- 

 angular ; fine-grained ; white colour ; lately dug up on the farm. 

 Boulder of sandstone, 22x20x12 in. ; sub-angular; fossiliferous. Boulder 

 of sandstone, 23x19x9 in.; rounded; gritty; grey colour; unfossili- 

 ferous. Boulder of dolerite, 30x26x17 in.; columnar dolerite; shape 

 well marked ; microcrystalline ; no striaa, but highly polished. 



2. Stebbing Green — Boulder of dolerite, 30 X 27 X 24 in. ; conical 

 shape, with semicircular base ; no striae, but highly polished. 



3. In fields near the Green — Five smaller boulders of dolerite under 

 12 in. in diameter, one being a highly vitreous olivine-basalt. 



4. At Green Farm — Boulder of quartz rock, 20 x 16 x 11 in. ; rounded ; 

 polished ; yellow colour. Boulder of quartzite, 16 xl2 x 11 in. Boulder 

 of felsite, 12x10x9 in.; oblong ; dark grey ; very compact and hard. 



