838 PRINCIPLES OF STRATIGRAPHY 



are several smaller cuestas, less continuous, but still in places quite 

 pronounced. These are carved out of the Ordovicic limestones, 

 where they rest on softer shales or sandstones. (Wilson-31.) 

 South of the Niagara cuesta are several others cut into the De- 

 vonic strata. The most pronounced is that of the Onondaga lime- 

 stone crossing the Niagara River at North Buffalo and extending 

 east across the State until it culminates in the Helderberg edge 

 northwest of Albany. This extends northwestward from Buffalo, 

 and crosses Lake Huron as a submerged ridge, finally reappearing 

 in Mackinac Island, beyond which it merges with the cuesta formed 

 by the Hamilton strata, which continues southward along the east- 

 ern border of Lake Michigan. 



Throughout western New York and Canada this cuesta is buried 

 under drift, but in Lake Huron, though submerged, it forms a 

 cliff 400 feet high, (Fig. 211.) A still higher but generally less 



Fig. 211. Cross-section of Lake Huron, from Point au Sable (a) across nine- 

 fathom ledge (b) to Cape Hurd (c), showing the submerged 

 cuesta and inner lowland. 



pronounced cuesta extends eastward across central and southern 

 New York, formed by the sandy Upper Devonic strata. Eastward 

 this, too, merges into the Helderberg escarpment. 



The Palfeozoic outcrops of northern Europe also fall into line as 

 parts of a series of discontinuous cuestas. Thus the drowned region 

 of the Baltic shows an Ordovicic cuesta series, partly submerged in 

 the islands of Oland, Dago and the coast of Esthonia, the infaces 

 of which faced the old land of Sweden and Finland. The drowned 

 inner lowland includes the Kalmar Sund in Sweden and the Gulf of 

 Finland in Russia. A second discontinuous cuesta formed of Silu- 

 ric rocks runs in a general way parallel to the first and farther to 

 the south and east. This comprises the islands of Gotland and Osel, 

 and continues in the Baltic provinces of Russia. Central Europe 

 has its main Mesozoic cuestas in the Swabian Alp which extends 

 across southern Germany as a bold escarpment of horizontal Juras- 

 sic limestones from Wiirttemberg to the borders of the Bohemian 

 forest. 



England, too, has its Palaeozoic cuesta in the westward facing 

 Wenlock Edge of Siluric strata. It has two distinct Mesozoic 

 cuestas : one in the range of oolite cliffs which extends from Dorset 



