712 
' Under every bed of coal which he examined, amounting to more. 
than twelve, Mr. Logan detected the stigmaria fire-clay ; and he 
was informed by Mr. Poole, the superintendent of the Albion mines, 
that similar strata occupy the same position in the coal-field of Cape 
Breton Island. 
The limits of the Nova Scotia coal deposits have not been de- 
fined, and Mr. Logan states that considerable difficulties would 
attend an attempt to trace them, in consequence of the overlying 
gypsiferous strata. He believes that the Pictou field extends west- 
ward across Colchester county to the north side of the Basin of 
Mines, and that the seams which dip to the north at Kemptown 
and Onslow may belong to its southern side; he also believes that 
a parallel trough ranges to the southward, from Hawkesbury in 
Cape Breton Island to Windsor, on the south side of the Basin of 
Mines (lat. 44° 49, long. 64° 19! west); and three miles further 
south he also discovered coal-measures, rising with a northwardly 
dip of 45° from below the gypsiferous rocks, and resting on granite. 
Coal is likewise reported to occur at Beaver Lake, south-east of 
the Albion mines, and to be brought down the East River during 
the spring floods, attached to floating ice. On the north side of 
the valley of the Stewiack, south-west of the Albion mines, coal- 
measures rest on a deep bed of limestone which dips to the south. 
The gypsiferous strata, and the associated shales, sandstones, and 
fossiliferous limestones, Mr. Logan is of opinion, are not only newer 
than the coal-measures, but overlie them unconformably, founding 
his conclusions respecting the geological age of the formation on its 
organic contents. ‘The fossils, he states, have been determined to be 
distinct from those of the carboniferous or any lower epoch, as well 
as from those of the lias or any superior deposit, but to have a de- 
cided generic agreement with the fossils of the triassic period. 
At Horton Bluff, ten miles north of Windsor, and not far from 
gypsum beds, but between which and the point in question is a 
fault, some dark-coloured argillaceous strata alternating with cal- 
careous bands are well exposed. Carbonized vegetable remains are 
not uncommon in these beds, which might easily be mistaken for 
coal-measures; but as one of the calcareous bands is nearly identical 
in character with the Windsor limestone, and as he also obtained a 
slab which appears to him to exhibit foot-marks, the author is in- 
clined to consider the deposit as affording collateral evidence of the 
age of the gypsiferous strata. 
A paper was afterwards read “‘ On the Tchornoi Zem, or Black Earth 
of Central Russia,” by R. I. Murchison, Esq., Pres. G.S. In this 
communication the author describes, first. the range and extent of 
the Black Earth; secondly, its chemical composition ; and thirdly, 
he offers some remarks respecting its origin. 
1. The northern boundary of the Tchornoi Zem may be defined 
by a line drawn in a curved direction from a little south of Lichwin 
(lat. 54° N. long. 33° 44’ E.) eastward to the Volga, in the 57th 
degree north latitude, occupying the left bank of that river west 
of Tcheboksar, between Nijni Novogorod and Kasan. It occurs 
