INTRODUCTION. 



7 



„ t, , . , , . . rUpper group : Fymtha hme- 



6. .Palaeozoic formation, ranging " .,i , , , 



... . ' stone with fossils of lower 



probably trom the cam- ., . 



f . / < Silurian age. 



brian to the upper silu- T j i v 



rL Lower group : Mandalay lime- 

 nan system. .,, , , ., 

 J \_ stone without fossils. 



2 Submetamorphic formation. 

 1. Gneissic formation. 



Volcanic rocks : Porphyry of unknown age, granite of gneissic 

 age. 



The gneissic and submetamorphic formations of this classifica- 

 tion need not be discussed now, but the 

 Palaeozoic formations. . . , . . , . . 



palaeozoic formation requires a brief notice. 



Dr. Noetling includes in his lower group, the Mandalay limestone, 

 not only the crystalline limestones of Mandalay Hill and other 

 isolated hills in the Irrawaddy plain, but also the limestones form- 

 ing the western slopes of the edge of the plateau, and the great 

 bulk of those on the plateau itself. But the discovery of fossils, 

 including Fusulina, at the very edge of the scarp close to Tonbo 

 (B 5), has proved that these limestones are of very much later 

 geological age than those of Mandalay and the Sagyin Hills, which 

 belong to the gneissic series of Mogok. And the whole of the 

 great limestone formation of the plateau has now been shown to 

 belong to the Devonian and Carboniferous systems, and therefore 

 to be of later date, than Dr, Noetling's Pyintha limestone. This 

 latter group also has been found to be only one member of a 

 series of Ordovician rocks, which are well exposed in the broken 

 country along the western edge of the plateau. A single de- 

 terminable fossil was found by Dr. Noetling in this limestone, and 

 enabled him to fix the age of the bed correctly as that of the 

 lower Silurian (Ordovician) of northern Russia ; though his identi- 

 fication of the fossil as an Echinosphcerites, and his description of 

 it under the name of E. Kingi, 1 have now been shown to be 

 erroneous. 



The ' red sandstones of undetermined age,' which occupy a far 

 larger area than was supposed by Dr. Noetling. 



Red sandstones. . ° . , , . „ 



have now been lound, on the evidence 

 of fossils contained in interbedded bands of limestone, to be of 



1 Field Notes from the Shan Hill* ; Records, Geol. Surv. Ind., Vol XXIII FV 2, 

 p. 78. 



