THE ANCIENT VOLCANOES OF DERBYSHIRE. 98 
tigation were corroborated by the Geological Survey, made about the 
same time. For nearly thirty years after this very little of any 
importance was done to further elucidate the problem. In 1894, 
however, Mr. Arnold Bemrose, of Derby, who had devoted much 
attention to the petrography of the ‘‘ Toadstones,” communicated a 
very valuable paper to the Geological Society, which served to bring 
the subject prominently to the notice of the leading geologists of the 
day, among them Sir Archibald Geikie, who resolved to visit Derby- 
shire ; and, under Mr. Benirose’s guidance, he made an inspection of 
the district where the volcanic evidences are to be found. His main 
object was to endeavour to discover remains of the ancient vents 
from which the lavas, agglomerates and tuffs had been ejected. In 
this research, greatly helped by Mr. Bemrose’s thorough knowledge 
of the locality, Geikie was entirely successful, for he became convinced 
of the existence of several distinct centres of eruption. Briefly sum- 
marised the following points were determined : 
(1) The voleanie region of Derbyshire is quite isolated from other 
contemporaneous areas of disturbance, the nearest being in 
Roxburghshire on the North and Somersetshire on the South ; 
(2) The district represents a thoroughly marine phase of volcanic 
action ; 
(3) The whole of the vents discovered are filled with agglomerate ; 
(4) A large number of sections are visible at various places, but 
much of the ejected material is concealed ; 
(5) The lowest horizon of the voleanic series is probably unknown, 
as the limestone amongst which they lie has not yet been pene- 
trated through its entire thickness; 
(6) The lowest known volcanic deposits lie at a depth of about 800 
feet below the upper beds of limestone; the highest in the 
series pass into the lower beds of the Yoredale Rocks which 
lie over the limestone ; 
(7) The thickness of the ‘‘ Toadstones ” varies considerably ; 
(8) The rocks in proximity to some of the voleanic beds have been 
much changed in character; in places the limestone has been 
altered into saccharoidal marble (Dale Farm, Peak Forest), 
and clays have been baked into columnar masses (Tideswell 
Dale). 
