i 



Vol. 50.] THE GEOLOGY OF MATTO GROSSO. 85 



1. The Geology o/Matto Grosso (particularly the Region drained 

 by the Upper Paraguay). By J. W. Evans, D.Sc, LL.B., F.Gr.S. 

 (Read November 8th, 1893.) 



[Plate VIII.— Map.] 



Contents. Page 



I. Introduction 85 



IT. Bibliography 8(i 



III. Physical Features of Matto Grosso 87 



Succession of Strata 88 



IV. Pre-Devonian Bocks 88 



CI. Ancient Crystalline Rocks 88 



| 2. Cuyaba Slates 90 



■{ 3. Corumba and Arara Limestones 91 



4. Rizarua Sandstone 93 



5. Matto Shales 93 



V. Devonian Rocks (Ohapada Sandstones) 95 



VI. Carboniferous, Trias, and Cretaceous 97 



VII. Quaternary ., 98 



VIII. Unclassified Rocks 99 



IX. Igneous Rocks 10(J 



X. Historical Summary 101 



XL Economic Products 102 



[Note. — The italic numerals in parentheses, throughout this paper, refer to 

 the works quoted in the bibliographical list.] 



I. Introduction. 



I spent some time in this part of South America in the years 1891 

 arid 1892, but unforeseen circumstauces seriously interfered with 

 geological work. The present paper is the result of such observa- 

 tions as I was able to make, and I have to thank the other members 

 of the expedition (including the leader, Lieut. 0. T. Storm, of the 

 Scandinavian Navy ; his brother, Mr. Johan Storm ; and Mr. 

 Spencer Moore, the well-known botanist) for doing all that was 

 possible to facilitate my labours. 



Very little has hitherto been known geologically of most of 

 the country I traversed. A short account of A. d'Orbigny's 

 valuable work in the adjoining portion of Bolivia in the year 1842 

 (1) is given in the present paper (p. 96). Castelnau visited Matto 

 Grosso in 1843-44 (#), Chandless about 1864 (<?), the Brazilian and 

 Bolivian Joint Boundary Commission in 1875-78 (5), and Von den 

 Steinen with Clauss in 1884 and subsequently (6) & (7) ; but they 

 have not given us any very definite geological information. Several 

 years ago Mr. Herbert H. Smith resided for about two years in tho 

 Chapada near Cuyaba, being engaged in zoological collecting. Some 

 fossils obtained by him were described by Mr. Orville A. Derby 

 in an important paper in which he summarized all that was then 

 known of the geology of Matto Grosso (8). 



