54 Mr. Farey’s Geological Observations in Durham, &c. 
whose massive straia appear to me to form part of the cone 
tinuous edge of Basalt, stretching (generally with a north 
western dip I believe) from near Montrost on the German 
Ocean, to Dunbarton on the Clyde, (and perhaps thence 
across Arran, &c to Rothlin and Antrim?) covering and 
limiting the great Coal-field of the Forth and Clyde; 
great part of which, it seems once to have covered, before 
the vast and complicated denudations were performed, 
which have in many parts cut deep into the Coal measures, 
and left numerous detached Hummocks of Basalt, like that, 
of Arthur’s Seat, and all others which I saw thence to near. 
Kinross, idan 
From Edinburgh [ returned by Haddington, Dunbar, 
Berwick, and Belford, to Newcastle; a day which I spent 
here, was lost as to any observations on the strata, owing 
to a dismal thick fog: next day I was more fortunate at, 
Sunderland and Durham: at West Bolden, I lett the Coal- 
Measures and ascended the regular edge of the lower yellow 
Limestone Rock, which I at once recognised, and descended 
it_again a mile NE of Houghton le Spring. At Ferry 
Hill f again ascended the edge of the lower yellow Lime- 
stone Rock, and was there hospitably entertained and 
much tastructed, by Mr. Thomas Arrowsmith, who works a, 
colliery through the lower Limestone Rock, as at Parling~ 
ton, Knitaker, Skegby, Nuthall, Bilborough, &c. are or hag 
been done, Derb. Rep. 1, 156, and Phil. Mag. vol. xxxix. 
p- 99 and 103. South of Ferry-Hill, I seon ascended an 
indistinct edge of the Red Marl between the Limestone 
Rocks, such as had often deceived me in Notts, and Der- - 
byshire, as mentioned Phil. Mag. vol. xxxix. p. 104, and 
then the edge of the upper Yellow Limestone, which dips. 
into. a trough at Rushyford, and is there covered by a 
clayey soil (perhaps alluvial?) which trough and covering 
Stratum, seems tome from my inquiries, to extend east-. 
waid by Sedgefield, or south of it, to the coast SW of 
Hartlepool ;-but these are points on which I am extremely 
desirous of precise information from your Correspondents. 
On the S of Aycliff I again descended the edge of the 
upper Rock, and came upon the Red Marl, here not am- 
biguous or doubtful, being thicker than at Fairburn (Phil, 
Mag. vol xxxix. p. 104), and thereon (or its imbedded grit- 
stone) I travelled, through Darlington, Croft, North-Cawe 
ton, Catterick-Bridge,, Leeming, and Ripon; soon after 
which, I descended again on to the top of the lower yele. 
Jow Lime Rock. (left on the S of Ferry Hill), and after 
seeing several large Lime-works therein, which Ne 
