70 SEVENTH REPORT—1837. 
On the Geology of Spain. By Dr. 'TRariu. 
In the sketch of the geology of the Spanish peninsula laid before 
the British Association in Dublin, the author gave a general yiew of 
its principal mountain chains, and a more particular account of the 
structure of Andalusia and New Castile. The basis of the mountains 
on the S.W. and N. of the latter is granite; which in the southern 
and western boundaries is directly covered by clay slate, and in the 
Guadarrama chain by gneiss and mica slate. In the Sierra Morena, 
the clay slate, reposing on the granite, strongly resembles the slate of 
Cumberland; and at Santa Elena, in the pass of the Sierra Morena, 
contains crystals of chiastolite. The primitive rocks of the central 
ridges of Spain are, on all sides, quickly succeeded by the old sand- 
stone formations ; on which we often find a very compact, greyish 
white limestone, with an imperfectly conchoidal fracture, which the 
author, from its geological relations, considers to belong to the Jurassic 
formation. This limestone is very widely distributed in the eastern 
provinces, from the mountains of Jaen and Granada to Gibraltar, and 
covers the flanks and peaks of the Sierra Nevada to the height of 
9000 feet, the highest point he was able to reach in the end of May, 
on account of the state of the perennial snow which invests it for 2000 
feet higher. This limestone is seen in the Sierra Carbonera, near 
Gibraltar, to rest upon old sandstone. Another limestone formation, 
of a more friable and gritty aspect, abounds on the flanks of the 
mountains, which he considers as the representative of the oolite of 
England. True chalk forms considerable tracks in Western Anda- 
lusia, especially near Lebrija; and considerable tertiary deposits 
occur in the plains and valleys south of the Sierra Morena. 
In that portion of his paper read before the Geological Section in 
Liverpool, Dr. Traill described the northern part of New Castile, part 
of Aragon, and Catalufia, including the celebrated salt mine of Car- 
dona. 
The plains between Madrid, the Somosierra, and the mountains 
dividing Castile from Aragon, chiefly consist of vast beds of marl, 
gypsum, and sandstone, over which, in some places, lies a limestone, 
which he considers as oolitic. He traced these formations through 
Grajanejos and Maranchon to Uset, the first village in Aragon. At 
Uset they disappear, and their place is supplied by a quartzose 
sandstone, splitting into thin layers, which may be used as roofing 
flags, and contain many crinoidal remains. This sandstone appears to 
rest on a well-characterized greywacke slate, devoid of organic re- 
mains. This last rock is well seen at the pass named Puerta de 
Daroca, where it contains thin beds of a very pure quartzose sand- 
stone flag ; and these strata are seen dipping below the more common 
sandstone that occurs near Uset. In descending from this pass, the 
sandstone may be traced to the banks of the Rio Xiloca, where it is 
covered bya thick bed of coarse argillaceous conglomerate, forming 
stupendous cliffs, overhanging the city of Daroca and its narrow 
valley. Red marl and gypsum reappear in the wider parts of the 
