BY W N. BENSON. 545 



seventeen miles, and, with a small area south of the river, it 

 comprises eighty square miles, including the Parishes of Woolo- 

 mol, Tamworth, and Nemingha, and portions of the Parishes of 

 Moonbi and Calala. A topographical and geological map of this 

 was prepared by a survey with a plane-table, and contour-lines 

 were drawn thereon at intervals of two hundred feet, determined 

 by aneroid-readings. The datum-points were the railway stations 

 of Tamworth, Nemingha, Tintinhull, and Moonbi (now^ renamed 

 Kootingal), which are respectively 1279, 1351, 1330, and 1381 

 feet above sea-level. The results of the geological and petro- 

 logical work, and of the determinations by Mr. Dun of fossils 

 collected, are here presented; the physiography will be discussed 

 in another communication. 



The result of the w^ork, as will appear, has been to confirm the 

 main points of the views held by Messrs. David and Pittman, 

 though some modification of the details has been found neces- 

 sary. It seems fitting to acknowledge here the generous help of 

 the officers of the State Geological Survey, and the writer's con- 

 stant indebtedness to Professor David for advice and encourase- 

 ment, both in the laboratory and in the field. 



'&^ 



General Geology and Tectonics. 



The result of the present examination shows that the fourfold 

 subdivision of the Devonian system, formerly proposed by the 

 writer, holds good for the Tamworth district, though the defini- 

 tions of the several sections need some modification, and it has 

 seemed best to unite the two upper divisions, and to subdivide 

 the large Middle Devonian series below these. On the other 

 hand, it has been found that the subdivision of the Middle 

 Devonian series, deduced from the study of the Nundle dis- 

 trict(15), does not hold good here, for the reason previously sug- 

 gested, namely, that the structure x>i the Nundle district is so 

 complicated by strike-faulting that the apparent succession is 

 probably not the true one. This appears very clearly from the 

 structure of the Parish of Nemingha, which is in a position 

 tectonically similar to that of the Nundle district. The succes- 

 sion in the less disturbed areas of the Parish of Tamworth is 



