90 REPORT—1840. 
lowest members of the lower coal series at Crossbasket. It is not tra- 
versed in Lanarkshire as in Ayrshire by trapdykes. 
2nd. The upper or fresh-water coal series contains about thirty 
seams of coal, seven or eight of which are workable. The first work- 
able coal lies generally about forty-five or fifty fathoms below the red 
sandstone ; but at Rosehall the red colour prevails as low in the series 
as the third workable coal. The first or upper coal seam is from 23 
to 3 feet thick in the parishes of Old and New Monkland ; but in those 
of Dalziel, Dalserf, and Hamilton, it sometimes measures from six to 
ten feet. When so thick, it is probably a junction of the first and 
second seams. The second and third coal, when separate, average 
each about four feet; when united, as is sometimes the case, they form 
eight or nine feet of coal. The fourth coal is generally too thin to be 
workable; but in the neighbourhood of Glasgow it measures 23 feet. 
The fifth or splint coal measures from 24 to 6 feet thick. The coals 
that underlie the splint are not so regular, either as to thickness or 
geographical distribution. There are three seams workable in the 
Monklands—the first is 2} feet, the next four feet, and the lowest two 
feet thick. Below these, in the parish of Shotts, there is a cannel coal. 
The distance from the first or ell coal, to the fifth or splint coal, is 
about thirty fathoms. The area in which these valuable beds of coal 
occur, extends in Lanarkshire from Glasgow to Carluke, a distance of 
twenty miles. In breadth it varies from six to fifteen miles: fifteen to 
twenty square miles of this area is occupied by the upper red sand- 
stone. 
The fossil shells found in this formation are all of fresh-water origin. 
There are from seven to ten varieties of the genus Unio. The different 
species are characteristic of different portions of the stratification, the 
larger species being lowest and the smaller highest in the series. The 
remains of the Megalichthys Hibbertii prevail from the lowest coal to 
the upper black-band ironstone. This is also the case with the Gyra- 
canthus formosus of Agassiz. The Ctenacanthus and two other species 
not yet described, are also found in the upper ironstone, and in the roof 
of the splint coal. These and other ichthyological remains are found in 
great abundance in the roof of the Shott’s coal, which is the second 
seam below the splint coal. The shales of this series abound in fossil 
ferns, Stigmaria, Lepidodendra, Asterophyllites, Sigillaria, and other 
coal plants. 
The Sternbergia approximata has been found in the roof of the 
splint coal. It is worthy of remark, that the Stigmaria ficoides is very 
frequently found in the shales, with the leaves attached to the stem 
and spread out laterally, in a manner which never could have occurred 
had the plant been drifted from a distance. The ripple-marks which 
are observable on almost all the shales and laminated sandstones, not 
only in the upper series, but through the whole of the carboniferous 
formation, tend also to show that these portions of the coal strata, at 
least, were deposited in shallow water. Fossil trees in a vertical situa- 
tion are rare. Mr. Craig had only seen them in three places,—that at 
Balgray Quarry, near Glasgow, is the most remarkable, as there were 
