1816.} Scientific Intelligence. 81 
lay, and contains Leds and veins of granite. I remained several days 
at Fort William waiting for clear weather to ascend Ben Nevis; but 
the continuation of the fog and the rain confined my labours to the 
examination of Glen Nevis and the base of Ben Nevis. The beds 
of granite, syenite, and porphyry, are truly magnificent, and in a 
geognostic point of view highly interesting. Near Balahelish ferry, 
noticed various alternations of clay-slate with lime-stone; vast beds 
of quartz and trap. The country around Mr. Stewart, of Balahelish, 
I knew from my young friend Mr. Walter Adam to be well deserving 
the particular attention of the mineralogist, and the few hours I 
spent there proved highly gratifying to me. The geognostic rela~ 
tions of the granite, syenite, porphyry, quartz, and other rocks, 
correspond with those I observed in Glen Nevis. At the great slate 
quarries belonging to Mr. Stewart I observed fine examples of clay- 
slate in distinct concretions of various magnitudes and forms, and 
which appeared to me to be illustrative of the chemical nature of 
clay-slate. _Glenco exceeds in grandeur and magnificence all the 
mountainous scenery I have hitherto visited in Scotland. In this 
valley a great bed of a singular rock attracted my particular atten- 
tion. It is composed of red granite, syenite, and porphyry, inter- 
mixed with enormous masses of quartz, which is sometimes pure, 
sometimes mixed with felspar or with mica ; and it is to be observed 
passing into granite, or into gneiss, or mica-slate. This curious 
mass. has sometimes a conglomerated character; and, when not 
viewed on the great scale, might in some places be considered as 
granite, in others as quartz rock, or gneiss, or mica-slate, or por- 
phyry ; whereas the whole énormous mass is probably a conglome- 
rated bed belonging to the mica-slate or clay-slate formation. The 
upper part of this glen, as remarked by Dr. Macknight, presents a 
grand display of porphyry rocks, and also those of the syenite for- 
mation ; and few quarters in Scotland afford so fine a field for the 
study of their various geognostic relations. Here, as in Glen Nevis, 
&c. many appearances occur which show how cautious we ought to 
be in inferring the relative position of rocks from the direction and 
dip of the neighbouring strata. From the dreary inn of King’s 
House the geognost can examine with ease the grand granite and 
syenite mountains that extend to Glenco and Inverouran; and 
at this latter place the connexion of the gneiss with these rocks can 
be satisfactorily ascertained. 
1 spent some time in examining the lead mine in the vast bed of 
quartz at Tyndrum. ‘The great conglomerate cliffs at Callender are 
trap tuff. Italternates with old red sand-stone. In Roxburghshire 
I find the predominating rocks to be greywacke-slate, greywacke, 
transition clay-slate, and red sand-stone, with its subordinate rocks. 
The transition rocks in this county agree with those which occur so 
abundantly in Peeblesshire, Berwickshire, Selkirkshire, Dumfries- 
shire, and Galloway. In Dumfriesshire [ traced the coal field under 
the red sand-stone. In Lanarkshire the red sand-stone contains beds 
Vov. VII. N° I. F 
