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or of the locally baselevelled tracts developed between 

 the more resistent members of the tableland. The an- 

 nexed diagram of the mountain crests as seen rising 

 above the lowland east of Curityba is typical of the 

 region for many leagues northward into the state of Sao 

 Paulo. 



Isolated summits in this region rise somewhat above the 

 level of the trap plateau. It is probable that in the late 

 Mesozoic baselevelling of the region the granitic bosses 

 and some of the gneissic areas were not reduced to the 

 general level. On the north the lofty Serra da INIantiqueira 

 culminating in Mt. Itatiaia nearly 10,000 feet in eleva- 

 tion, warrants this statement. 



The slope from the crest of the Serra do Mar to the sea 

 is generally steep. It is deeply ravined by short streams. 

 The interstream areas form sharp spurs which in some 

 portions of the slope are deeply dissected, standing out as 

 isolated peaks and mountain blocks as on the south side 

 of the harbor of Rio de Janeiro. The immediate descent 

 to the sea is often so precipitous and the relief so high 

 that where the geological structure is permissive of the 

 hypothesis down-faulting on the ocean side has been advo- 

 cated as by Dr. Derb\- as a factor in the production of 

 the topography. 



This deeply dissected slope has been depressed beneath 

 sea-level since its dissection arrived at an advanced stage. 

 The submerged valleys form harbors and reentrants such 

 as those of Rio de Janeiro,Santos, Itajahy, Sao Francisco, 

 and Florianopolis.^ Since this depression in relation to 

 sea-level took place, a slight uplift of about ten feet (3 

 meters) has occurred, raising up in the form of a plat- 

 form about bay shores a recent deposit of littoral sands, 



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1 The frequent repetition of tlie circumlocutions one is obliged to 

 employ in expressing concisely the fact of our ignorance as to whether 

 the land has stmk or the sea-surface risen when reference is made to a 

 change of level of land and sea becomes intolerable in writing at length 

 of such matters. Suess's terminology partially avoids the embarrass- 

 ment but does not pro\ide a name for a change of level of land and sea. 

 The French term denivellement, a variation of level, suggests the use in 

 English of its natural equivalent deleveUing in analogy with baseletelling. 

 A positive delevelling thus becomes a depression of the land in relation 

 to the sea-level, and a negative deleveUing an apparent elevation of the 

 land in relation to the surface of the sea. 



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