1822.] Mr. Winch on the Geology of Lindisfarn. 429 
with veins of white calcareous spar, and the casts of the encrinal, 
fossil, and obscure bivalve shells, are imbedded’ in it. Four 
inches of highly indurated shale, of an iron-grey colour, and 
breaking into angular fragments, may be remarked between the 
limestone and basalt. A little to the east of the boat houses, 
shale, containing marine exuviz, underlies the basalt, and at one 
point may be seen in the cliff, 20 feet above high water mark. 
To the eastward of the path which crosses the Heugh, shale 
or slate clay is the stratum on which the basalt again reposes. 
At the point of contact, the shale of the upper part of the bed 
is of an ash-grey colour, and its fragments are angular; it con- 
tains specks of calcareous spar, and is hard, when compared 
with the schistose layers under it. These are of a pale-grey, 
passing into reddish-brown by decomposition, and abound in 
casts of the following organic remains : 
Helix cirriformis, Sowerby .... T. 170, f. 2. 
Terebratula biplicata, ditto.... T. 90, f. 1. 
Terebratula Wilsoni, ditto .... T. 118, f. 3. 
Spirifer trigonalis, ditto ...... T. 265. 
Spirifer oblatus, ditto ........ T. 268. 
Productus longispinus, ditto .. T. 68, f. 1. 
Productus Flemingii, ditto.... T. 68, f. 2. 
Also a small bivalve, probably a Modiola, and a fossil, resem- 
bling a Belemnite, but not thicker than a quill, though of consi- 
derable length. 
The bed of shale lying at some distance from this part of the 
Heugh, and covered by the sea at high water, is very hard, 
black, and encloses calcareous casts of the encrinal fossil, and 
cubic pyrites, and the organic remains before enumerated. 
The basaltic eminence on which the castle stands is the most 
striking feature of the island, the summit of the rock being 
decidedly columnar : it is of the same nature as the Heugh, and 
rests upon shale of the same description; but on the beach 
immediately below the gate leading into the castle field, a small 
portion of very beautiful limestone may be noticed ; its colour is 
pale reddish-brown passing into bluish-white ; its lustre pearly ; 
and texture highly crystalline, similar to the last mentioned 
limestone, when in the vicinity of basalt. The strata of lime- 
stone and shale along this side of the harbour from the Heugh 
to the castle, where exposed to view at low water, may be 
observed to possess an undulating form, the ridges rising at 
right angles to the inclination of the beds, but this phenomenon 
is more remarkable at the Coves. 
From the castle point to Red Brea, the cultivated land is 
defended from the mroads of the sea by a barrier of boulder 
stones thrown up during easterly gales of wind. On examination, 
these will be found to consist of the same varieties of rocks as 
those imbedded inthediluvium. From this stony beach to beyond 
