1 889.] Geology and Palceontology. 257 
the present peninsula had emerged, including part of the 
Basque provinces, eastern Castile and northern Andalucia, 
while the remainder of Andalucia was occupied by many- 
islands. 
Subsequent submergence made the Cretaceous seas larger,the 
eastern coast of the principal mass receding to the line of San- 
tander, Reinosa, Burgos and Segovia, while a gulf extended in 
the north from Santander almost to Oviedo, and the Pyrenees 
were partly submerged. Yet in the same period the islands of 
Aragon and the eastern part of Castile became united into a 
peninsula, joined to the mainland by a narrow Isthmus at 
Avilar. This peninsula extended southward to the Sierra 
Albarracin. At the same time the islands between Burgos and 
Calatayud became united into one, those along the coast from 
Gerona to Fortora also joined, and those of Murcia became 
united to the great southeastern island. 
At the end of the Cretaceous period the peninsula was com- 
pleted almost as it now stands, except that the sea covered the 
entire basin of the Ebro, penetrating between the islands of 
the coast from Gerona to Murcia (again partially submerged) 
and through passes opened in the Pyrenees. There was also 
a narrow lake in the center of Galicia. During this period 
immense nummulitic deposits accumulated in the Ebro 
basin, until the sea finally shallowed into a series of lakes, 
which in Eocene times filled up with a different series of de- 
posits. 
In Miocene times, the sea penetrated only between the 
Murcian and Andalucian islands, into the basin of the Guadal- 
quivir, in the north at some points in Galacia, and along a 
narrow zone on the eastern coast. Lakes still existed in the 
basin of the Ebro, and also through most of the provinces of 
the Castilles and Leon. In Portugal a number of smaller lakes 
occupied much of the area about Leiria, Lisboa, Evora and 
Castro-Verde. 
In the Pliocene age the sea still penetrated by various 
points, especially into the valley bed of the Guadalquiver. 
Many small deposits occur in the valleys. All that the Post- 
pliocene has done has been to fill up various depressions with 
extensive diluvial and alluvial deposits. 
