56 



There has been a considerable outflow of lava from the 

 crater at an early stage of the eruption. This lava sheet, 

 which is often very compact, and frequently contains crystals 

 of olivine, can be seen in section both in the cliffs of the Valley 

 Lake ana the Blue Lake. Only a small amount of ash was 

 ejected before this outflow, as is evident by the thin deposit 

 that u'.idcilies it, varying from almost nothing up to 2 or 3 ft. 

 in thickness.: 



The normal level of the ground before the eruption is indi- 

 cated by the upper surface of the Eocene limestone, or a thin 

 layer of sandy soil (presenting now a reddish color), which in 

 places can be seen to rest upon this limestone, separating it 

 from the ash or lava beds. The Eocene beds are not visible 

 within the limits of the crater, but they take the form of mural 

 cliffs in the lowest exposed positions surrounding the sunken 

 areas of the Valley and Blue Lakes. 



The main stream of lava appears to have flowed in the 

 direction of the Blue Lake, as the thickest section (about 50 ft.) 

 occurs in the vertical cliffs of this lake on the side nearest to the 

 crater. When this fine sectk)n of lava is viewed from a boat 

 on the water it is peculiarly striking and awe inspiring. The 

 flow in this direction is somewhat irregular, and seems to have 

 thinned out considerably on the eastern side of the lake. In 

 places some instructive sections can be seen where the lava has 

 ploughed up the ash and soil over which it has passed, throw- 

 ing the layers into contortion and consolidating the material 

 under igneous action. Good examples of these effects are 

 visible by the side of the path which leads down from the 

 pumping station to the boathouse^ 



Ejectamenta. — The structure of the volcanic cone is remark- 

 ably uniform. The stratification where visible is regular and 

 unbroken, giving no evidence of rupture by igneous intrusions. 

 On the outer slopes of the Mount the volcanic tufa has been 

 reduced under atmospheric conditions to a fine dust, but within 

 the crater the beds are somewhat indurated, probably from 

 heat, which has enabled them the better to res. t the disinteg- 

 rating forces. 



Evidences are abundant that the volcanic fires broke through 

 solid beds of rock in reaching the surface. Large blocks of 

 the local limestones, red and grey dolomite, fossiliferous 

 Eocene, black flints. Tertiary sandstone, and angular frag- 

 ments of lava are abundant, as well as volcanic bombs com- 

 posed of lava or olivine. The dolomitic limestones are altered 

 fossiliferous beds of Eocene age, and are found in situ over- 

 lying the latter in many parts of the district. The ejected 

 fragments of dolomite are indistinguishable in their structure, 

 color, and composition from the stones that are quarried at a 



