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of Exmoor, but a distinct formation superior to the floriferous grits 
or culm measures (No. 9,) of central Devonshire, and consequently 
the newest deposits of the country. For this formation he proposes 
the name of Killas or Cornish, and he considers it as No. 10 in the 
ascending series. According to the new arrangement therefore, in 
proceeding from those parts of West Somerset bordering the Bristol 
Channel to the south of Devon and Cornwall, he conceives a regular 
ascending series is passed over, the central portion of which he is of 
opinion, consists of the floriferous grit or culm measures (9). He 
places the whole series also in the graywacke system. 
Mr. Williams’s reasons for this arrangement are drawn from ob- 
servations made at several localities in South Devon. 
At Doddiscombe Leigh, about four miles to the north of Chud- 
leigh, the Posidonia limestone, a member of No. 8, the Coddon Hill 
grit, underlies, Mr. Williams says, a long series of alternations, 
exposed on the turnpike road towards Chudleigh, and consisting of 
high hills of Coddon and floriferous grits with intercalated killas, 
the whole dipping beneath the coral limestones of Chudleigh, which 
pass under the ridge of Ugbrook considered by Mr. Williams to be 
composed of floriferous grits. On closely examining the limestones 
about Chudleigh, the author discovered minor alternations, which 
exhibited in juxtaposition the several varieties of Cornish killas, pale 
green, light blue, and purple volcanic ash and Coddon Hill grits (the 
two latter containing plants), interstratified beyond any doubt among 
the coral limestones, and these limestones inclosing carbonaceous — 
beds, underlaid and overlaid by thick accumulations of Coddon Hill 
and floriferous grits. On the road by Grayleigh, and descend- 
ing further on to Waddon Burton, Mr. Williams has traced these 
alternations foot by foot, and he says the sequents are so manifestly 
palpable in their interchanges, great and small, that nothing is left 
for inference or conjecture. 
The inseparable connexion of the coral limestone and Cornish 
killas with the floriferous series, he states, is also most plainly ex- 
hibited to the N.E. of Kingsteignton, at Ashburton, Newton 
Bushel, Abbots, and King’s Kerswell, Marldon, Berry Pomeroy, 
Higher and Lower Yalberton, and thence to Brixham and Berry 
Head. At Meadfort sands, on the south, the author says, there is 
a strange intermixture, yet in regular stratified order, of Cornish clay 
slate, and buff-coloured, finely arenaceous beds inclosing shells and 
corals, with true floriferous sandstones containing plants, also with 
culmy slates, and strata of volcanic ash and coral limestones, forming 
an anticlinal axis, ranging north and south, and throwing off the great 
mass of the Torquay limestones to the east and west. 
To the east of Dartmoor, Mr. Williams has little doubt the same 
alternations on a great and small scale occur, as far as the parallel 
of Torquay, immediately to the south of which line, but west of the 
bay, are said to be lofty conspicuous hills of the floriferous strata (No. 
9), which he conceives “‘ may be abruptions’; but their bases are 
commonly concealed by a thick mantle of new red sandstone. To 
the west of Dartmoor, independent of what he believes to be an axis 
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