170 
NATURE 
[OcToBER 9, 1913 
distinguishes it from the bituminous shales found 
throughout the Estuarine Series, all of which 
crumble into small fragments. It is so far known 
only from natural exposures, where through 
weathering, it assumes a lilac or yellowish 
coating. 
The thickness of the seam at the outcrops may 
be taken té be from seven to ten feet, but its 
passage into the overlying sediments is gradual. 
The samples so far analysed were much 
weathered, so that we are not yet in possession 
of exact data concerning the yield of oil and bye- 
products from the fresh shale. That the fresh 
shale might be expected to yield more than 
weathered portions seems probable, but to what 
FEET 
LOWER PORTION OF 
GREAT 
* | ESTUARINE SERIES 
‘| LOWER 
OOLITE 
| SANDSTONES 
2001" 
ER LIAS SHALES 
| Lilie Bnbag Oolitic Limestone 
MIDDLE LIAS SANDSTONE 
SEA LEVEL 
Diagrammatic section illustrating the sequence of the 
Jurassic rocks in the cliff between Holm and Prince 
Chailes’s Cave, Isle of Skye. 
extent is not known, and it is on that that the 
industrial possibilities of the find depend. 
A sample from the outcrop where the shale was 
first detected in Raasay gave 12 gallons of crude 
oil per ton of shale, with 6'2 Ibs. of sulphate of 
ammonia, which is equivalent to at least 12 lbs. in 
a works retort. 
A compound sample from the Skye coast be- 
tween Holm and Prince Charles’ Cave yielded 
12°8 gallons of crude oil per ton, and 7-4 lbs. of 
sulphate of ammonia. Mr. D. R. Steuart, who 
kindly undertook these tests, states that the 
samples were so weathered that he did not expect 
to get any -oil. Consequently these results in- 
dicate that the shale is worth further investiga- 
tion. 
NO. 2293, VOL. 92] 
Before the period of denudation which removed 
so much of the Scottish Jurassic rocks, the shale 
probably extended over a largé area. Still, the 
portions that escaped denudation are not incon- 
siderable. In Raasay the field occupies an oblong 
area stretching from Dun Caan northwards to the 
boundary fault which throws the Mesozoic rocks 
against the Torridonian. It is three miles long, 
with an average width of seven-eighths of a mile, 
which diminishes southwards. The strata are not 
folded, but have a dip of about 10 degrees to the 
west. 
In the Portree district of Skye there was. once. 
ofOLM 
ISLAND 
Sketch map showing the outcrops of the Oil Shale. 
Oil Shale. 
=—<—== Oil Shale, where burnt by contact action of igneous rocks. 
Faults, 
an extensive field, of which much has been de- 
stroyed by the contact action of intrusive rocks, 
The crop has been traced from Ollach—five miles. 
south of Portree—to the Holm burn—five miles 
north of Portree. The outcrop south of Portree 
shows much alteration from heat, except between 
the Tom cave and the Clach Dubh. North of 
Portree the destructive action of the intrusions is 
felt as far as Prince Charles’ cave, but between 
that point and the Holm burn—one and a half 
miles further north—the shale has escaped the 
action of igneous rocks. There is no inland ex- 
posure of the oil shale horizon, which is every- 
where covered by higher beds; consequently the 
