TRANSACTIONS OF THE SECTIONS. 07 



_ The bright claret-coloured slates at Mutley, north of Plymouth, "draw a fransi- 

 tioinil character to Old lied Sandstone, but no sandstones are seen, and the further 

 we cross the beds to the north the less are the axes upraised, and the slates may 

 have overlapped the Old lied and rested on the granite before it was upheaved ; but 

 when this took place the beds which skirt it were compressed into far less space than 

 they had previously occupied. 



If the Staddon beds are above the Plvrnouth limestone they must be overlapped 

 with a wide unconformity by the (Julru Measures of Tavistock and Launceston ; but 

 the Cuhn Measures of North Devon are, on the contrary, perfectly conformable to 

 the underlying series. 



The Fossihferous beds of Whitesand Bay, in the strike of the Plymouth lime- 

 stone, are also probably older than that limestone. 



In the Brixham area the limestone of Higher Brixham, extending from a little 

 west of that town to Sharkhain Point, is doubled under beds to the south older 

 than itself. This is seen to be the case near the Point, the base of a sharply doubled 

 inclined trough being well exposed above the sea-level, the contorted Bed Sand- 

 stones of Southdown Cliff corresponding with an anticlinal. 



The beds are not cut out by a fault along the strike, and it is a mistake to repre- 

 sent the iron-ore of Sharkhain Point as a lode. 



In the Torquay district, provided that the Cockington Bed Sandstones, like those 

 of the Lincombe and Warberry Hills, can be shown to be older than the limestones, 

 these last must be the newest Paheozoic beds of the Promontory; but they are not 

 seen in their natural relations, the intervening space being marked by New Bed 

 Bocks. 



The Great Devon limestones, then, are, as Mr. H. B. Woodward has said, the 

 highest rocks of South Devon, and the belief in a series of slates and Bed Sand- 

 stones overlying them is a fallacy. 



The beds which do succeed the limestones are the Culm Measures (Upper Car- 

 boniferous), and, from the field work of Messrs. Woodward and Beid, there is reason 

 to believe them perfectly conformable. 



In this case the difference between the Devonian and Carboniferons Limestones 

 would be one of life distribution— a geographical and not a chronological difference. 



Tins would probably have been long ago recognized had the characteristic Ich- 

 thyolites of the Old Bed occurred in the Staddon beds. 



If any doubt remains as to the position of the Great Devon Limestone, it might be 

 brought to a practical test by boring through supposed Upper slates. 



In America we are told that Old Bed Sandstone overlies Devonian rocks and 

 fossils. But can the Great Devon Limestone with certainty be equated with any of 

 the formations beneath the Catskffl beds ? It is very doubtful, and their Lamelli- 

 branchiate Fauna is said to present somewhat of an Upper Silurian facies. 



If this be so, thosegeologists may be quite right who look for marine equiva- 

 lents of the Old Bed, in some parts of the world, bridging over the Siluro-Carboni- 

 ferailfl interval. At the same time, in not admitting that the Great Devon Lime- 

 stone is such an equivalent, future observers would be unfettered in working out 

 the structure of Devonshire. 



On the Origin and Antiquity of the Mounds of Arkansas, U.S. 

 By Prof. J. W. Clarke. 



These mounds form a prominent feature of the State. They are present on all 

 soils capable of cultivation, alike on the small prairies, in the densest forest, and the 

 tablelands of the Ozark Mountains, but excepting the bottom-lands of Arkansas 

 and Mississippi rivers. They vary from 3 to 5 feet in altitude, and are from 50 to 

 140 feet in diameter. 



The author suggests that they were evolved from the simple corn-hillock by a 

 race who followed the retreating glaciers. 



