Dr Hibbert on the Rocks of Shetland. ^97 
be placed between 59° 53', and 60° 56' north latitude, and be- 
tween 52 ' and 1° 57 ' of west longitude from London. 
The stratification of Shetland cannot be considered as fallings 
under the particular views of the celebrated Werner, who sup- 
posed that strata lay over each other like the coats of an onion, 
whilst the whole had reference to an unstratified fundamental 
rock, as for instance, to Granite. But in the progress of obser- 
vation, certain other conditions of stratification have been pointed 
out, particularly by the Professor of Natural Plistory in the 
University of Edinburgh, to whom we are indebted no less for 
the introduction in this country of the W eriierian System, than 
for several important modifications which it has undergone, and 
which he has been accustomed so ably to illustrate in his lectures. 
The denuded state of the rocks in Shetland, recommends 
this country as a particular object of geological study. It is, 
however, a country which, by the few geologists who have visi- 
ted it, has been considered as possessing the greatest }3ossible in- 
tricacy of structure. Indeed, on this account, I feel myself un- 
der the necessity of employing more precise language than is 
commonly deemed necessary in subjects of this nature, in order 
to explain with less difficulty the different circumstances of stra- 
tification which presented themselves to me in these islands. 
In the first place, in describing strata which are vertical, we 
may conceive of them as the metallic plates which are ranged 
in the usual manner in a galvanic trough ; or, we may so alter 
the condition of the series of the plates, as to cause their planes 
to represent any angle of inclination between a horizontal and 
vertical position, which a stratum may form with the horizon. 
A stratum may ^ then be described as having two lateral planes^ 
the eastern coast of Unst, as given in Arrowsmith’s map; and, lastly, an excellent 
survey of Balta Harbour, published last year by Captain Ramage of the Royal 
Navy. With this paucity of materials necessary for producing a geological map 
of Shetland, it is proper to premise, that the sketch annexed to this communi- 
cation, is the result of observations made with no other instrument than a pocket 
compass. Still I flatter myself, that, though intended for a country exceeded 
by no other in the number and tortuous course of its inlets, the sketch will he 
found adequate to the purpose for which it was designed. I have occas^ionally avail- 
ed myself of observations, with which I was favoured by the late Thomas M^.<uatp 
Esq. of Garth, a gentleman of considerable intelligence, and particularly versed in 
the ancient history of his country. 
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