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3. The author then traced the different rock formations from the 
Sierra Morena to the south and south-west. 
In this Sierra he found in the upper regions gray and red granite, 
the latter often containing crystals of andalucite ; and syenite also 
occurs in some places. These rocks are generally covered by a very 
shining mica-slate ; but in descending towards the south, this is 
succeeded by clay-slate. At S ta - Elena this slate contains many 
crystals of ehiastolite, exactly like that of Cumberland. A little 
south of S ta - Elena he found true grauwacke and grauwacke slate, 
or unmistakeable Silurian formations ; on which reposed oolitic lime- 
stone, containing ostracites, and other shells. 
The Oolite occurs in other parts of Andalucia, as already noticed ; 
and it forms extensive tracks between Tarifa and Conil. 
Still newer formations begin in the valley of the Guadalquivir, 
and in the country between Sevilla and Xeres. At Lebrija are hills 
of indurated chalk, containing flint. Tertiary formations occur 
between Cadiz and Gibraltar, as well as in other valleys of this pro- 
vince ; so that Andalucia presents formations belonging to all the 
great geological epochs. 
4. The Sulphur Mine lies near the sea, about three miles east of 
Conil. It occupies a small oval valley surrounded by oolitic rocks, 
and is filled with a bluish marl, the matrix of the sulphur. The 
sulphur is often finely crystallized in its cavities, and is accompanied 
by crystals of sulphate of lime and calc-spar. The mine was wrought 
until about the time of the French invasion of Spain. In 1814 it 
was not wrought ; but this seemed less from exhaustion of the 
sulphur, than from the troubles of the Peninsula, and the want of 
fuel to sublime the sulphur. Magnificent crystals of this sulphur 
are in the royal cabinet at Madrid. 
The author concluded by some speculations on the origin of the 
sulphur in the Mine of Conil. 
2. Remarks on a Slab of Sandstone containing numerous 
Cavities, apparently produced by Marine Animals. Ry 
Charles Maclaren, Esq. 
This slab was found lying on the sand about 150 yards within 
high-water mark, a little northward of the projecting headland 
called Whitberry Point, on the coast of East Lothian. The head- 
