EEVIEWS. 
235 
of Santandar, an area some GO miles by 25, and an outline of tlie .geology. 
Mountain- chains are its dominant physical feature, the southern boundary 
resting on the Cantabrian chain. The centre and south-west of the pro- 
vince are occupied, according to the authors, by two groups of rocks ; one, 
the most massive, and constituting some of the highest peaks of ihe south- 
west, is represented chiefly by a limestone remarkably jagged in its out- 
lines, hard and splintery, generally white externally, where exposed, but 
greyish internally, and often almost black in its lowest part. At its base 
this limestone seems to be associated with a hard grey sandstone rock, 
and both rest unconformably on thick beds of shite-clay. Beds of con- 
glomerate, formed chiefly of quartz pebbles, with an extremely hard 
siliceous cement, are associated with the slate-clay. The limestone rocks 
a])pear very much upheaved, and the strata are of the nearly vertical, and 
forming a succession of anliclinals, the general strike of which may be 
taken as E. a few degrees W. 
The second group of rocks consists of beds of variegated clays alter- 
nating with soft sandstone beds of slatc-clay, thin beds of marly limestone 
of a dark grey colour alternating with thin layers of black marly clay. 
The predominating colour of the sandstones is red. The limestone rocks, 
upon which the beds of clay, sandstone, etc. rest, rise to the south and 
south-west in the lofty mountains of the Picos de Europa. 
After detailing with full particulars numerous sections, the author 
attempt to summarize and deduce the stratigraphical succession and 
relative ages of the different rocks. To do this, they first take such hori- 
zons as are naturally suificiently definite. The nummulitic series offers 
one wliich is not only convenient as the newest or uppermost, but is also 
topographically the first, being near the sea-shore. The nummulitic rocks 
rest on cretaceous beds, a\ Inch occnp}^ a narrow band of country near the 
sea, in the west of the province, and become largely developed towards the 
east. Those on the north side of the Ba}-- of Santandar have been studied 
by M. de Verneuil, wlio considers the beds lying between the Bay and 
tlie lighthouse to belong to the Upper Chalk Marls, and the authors suffi- 
ciently establish their position as the first horizon below the nummulitic 
beds. Those beds which form the quay of Santandar strike off towards 
the west, and arc found not only to overlie the dolomite of Pefia Castillo 
and the immense mass of the same rock lying about the south-west of the 
Bay of Santandar, but may be traced along the coast up to San Pedro, 
and inland to Jveocin and La Florida. This dolomite is in some places 120 
metres thick. The beds which underlie contain Calamophi/llia Stokesii, 
RliynchoneUa rimom, O.strea delloidea, Photodomya lyraia. Ammonites 
hifrons. Ammonites .serpen tinus. Pectens and belemnites are seven, which 
are undoubtedly Jurassic, while in the dolomite itself ammonites similar to 
those of the underlying beds. The authors therefore put this dolomite at 
the top of the Jurassic series, and make of them a second well-defined 
horizon. 
About the upper boundary there can be no difficulty, but it is otherwise 
with the lower limits. Beneath the dolomite are a series of beds of hard 
shelly argillaceous limestone, w ith variegated clay-beds passing into red- 
dish-grey sandstone, beneath which are thick beds of red micaceous sand- 
stone ; next follow the beds of compact blue or black limestone, containing 
metalliferous deposits, and forming the axis of the east and west chain 
called the Dobra. Bevond Monte Dobra, in the valley of Los Corrales, 
there is a repetition of the thick beds of red sandstone. In the upper 
members of this scries many Jurassic fossils have been found ; but, accord- 
