STRATIGRAPHIC GEOLOGY 213 



"Upon the shales rest the red sandstones like those near Abaete on the 

 banks of the Borrachudo and the Chumbo. They belong to a formation above 

 the clay shales. Between the serra do Capacete and the banks of the Indaia 

 there are rolled stones on the tops of the mountains that show the great 

 action of water in this part of the province. . . . Finally, intercalated with 

 the clay shales are enormous beds of limestone, and above them ferruginous 

 conglomerates. These conglomerates are seen near the village of Dores along 

 much of the road leading from the village of Carmo to the town of Dores." 



The conglomerates and water-worn rocks mentioned by Dr. Oliveira 

 are in the region in which Dr. Lisboa later found the faceted pebbles. 



Dr. Antonio Olyntho, speaking of the watershed between the Abaete 

 and the Borrachndo, mentions "nma argilla branca com caprichosos 

 arabescos." ^- 



In connection with the subject of Permian glaciation in Minas the fol- 

 lowing is of especial interest : The French geologist Francis de Castelnan, 

 who went from Pitanguy to Bom Despacho, in the State of Minas, in 

 January, 1844, made the follomng notes on the geology: After leaving 

 the city of Pitanguy, he crossed the Eio Para and passed fazenda Santa 

 Cruz. He then says :-^ 



"On the 22d we made three leagues in the same direction. The formation 

 is clay shale, probably resting upon gneiss. One league from Santa Cruz 

 (fazenda) one begins to find scattered about a great quantity of granite 

 blocks that look like erratics; they can not come from slides ('d'eboulement') 

 from the mountain, for there are none in the vicinity. Never having seen any- 

 thing of the kind in the whole course of our expedition, it is only with doubt 

 that we refer the rocks in question to such an origin; it is very likely that 

 they owe their origin to some local phenomenon. . . . The formation in 

 general is clay shale (schiste), gray, ochreous, and reddish, dipping to the 

 east, but half way between Trigueira and Bom Despacho the ground is cov- 

 ered by a sheet (coulee) of rose-colored granite which looks like a kind of 

 syenite. On both sides of the road one sees over the plain a considerable 

 quantity of granite blocks that have the appearance of being erratic. The 

 land is rather flat on the whole, and one sees these blocks on the steep slopes 

 right away up to the hilltops." 



These observations by Castelnau must be regarded as especially sug- 

 gestive and valuable in connection with the subject of Permian glaciation 

 in Minas. A little farther southwest, on the road between Formiga and 

 Bambuhy, Pohl noted red and yellow clays and clay shales.^* 



Mr. H. E. Williams, of the Servico Geologico do Brasil, in a private 

 letter dated August 26, 1918, writes : 



" Viagem aos terrenos diamantiferos do Ahaete. Annaes da Escola de Minas, no. 4, 

 p. 141. 



-•'' Francis de Castelnau : Expedition dans les parties centrales de I'Amerique du Sud. 

 Hi^*-orie dn Vovaee. vol. i. pp. 276-278. Paris. 18.^0. 



2* Job. Em. Pohl : Beytrage znr Gebirgskiinde Braziliens. Wien, 18.32. 



