OF THE SERGIPE-ALAGOAS BASIN OF BKAZFL. 421 



2. Oil the hill-tops -west of Maroim, and beyond (from the town) the church 

 Maroini de Cirau. 



3. Fazenda de Sto. Antonio, three-quarters of a mile west of the church. These 

 (iiKut/iti's are also on the hill-tops. 



4. East of Sto. Antonio, and visible from the church of Maroim de Cima is a 

 hill covered with quartzite. 



5. Immediately north-west of Maroim on the hill-top, exfoliating in blocks. 

 Along- the Estrada Real also north-west of Maroim, a bed one to two feet thick is 

 exposed. The Santa Cruz chuich north-west of Maroim is on a hill of ferruginous 

 conglomerate, bare of vegetation. 



SUKFACE GEOLOGY. 



Post- tertiary. — On the hills west of the Cotinguiba at a sitio near Maroim known 

 as Sitio de Bclcmges, and again along the hills about the Santa Cruz church north- 

 west of Maroim, are types of a formation overlying the teiliary. This formation ia 

 spread over the hills and valleys of the Scrgipe-Alagoas basin and over the adjacent 

 counti-y in the form of a thin coating of cobblestones, pebbles and sand, sometimes 

 loose and sometimes cemented into a pudding-stone as much as ten feet in thickness, 

 and, when exposed, stained black by manganese. It caps the summits of the tertiary 

 plateaux or their outliers, and it is frequently strewn along down the sides of hills 

 and accumulated in the valleys. It is not confined to the geographic limits of the 

 cretaceous or tertiary, but is found further inland and far beyond the present limits of 

 these formations. It is everywhere more or less irregular in thickness, and nowhere 

 can it be said to be univcisal or continuous. The writer has seen this material 

 throughout Sergipe and Alagoas, in Parahyba, and as far inland as the headwaters of 

 the Kio Ipancma in the interior of the province of Pernambuco, where there is no 

 remnant of stratified tertiary beds. Between the lower Rio Sao Francisco and the 

 frontier of the province of Alagoas, and indeed in many parts of the province of Per- 

 nambuco, this water-worn material is found minfjled in boirs with the remains of ex- 

 linct, gigantic mammals. 



One of the marked characteristics of this post-tertiary formation is that it is 

 much coarser inland, and grows finer as the coast is approached. The explanation 

 of this water-woin material seems to be that the tertiary i)eriod was closed by a 

 dci)ression along the present coast, which carried the beach liue far inland, or that 

 it was already there. Then followed a gradual emergence, during which the whole 

 aica MOW covered by this widely distributed water-worn material was passed gradu- 



