NOTES ON THE igi6 ERUPTION OF MAUN A LOA 483 



cindery a-a. These flows spread indiscriminately over the various 

 materials of the old surface and near-by areas of the lava of 1907. 

 At and near the sources the following types of new lava were 

 observed : 



0) PRODUCTS OF FLOW 



Pahoehoe, which here exhibits various surface textures deter- 

 mined by the interrelationships of different conditions during the 

 progress of flowing, such as the degree of viscosity (dependent in 

 part upon the temperature, the gas content, its state of solution, 



Fig. 4. — A view looking southeast, showing the cone at the head of flow, thin, 

 fresh pahoehoe spread over old pahoehoe and a-a, and the south terminal of the line 

 of solfataras. This cone is from 15 to 20 feet high. 



the amount of the crystalline content, etc.), the mass, and the 

 gradient of the surface, all these influencing the rate and manner 

 of flow and the consequent action of subsurface traction on the 

 crusts. 



Textures 



Pumiceous texture, a finely vesiculated spongy surface very 

 closely resembling basaltic pumice in color and structure. 



Lacy texture, a more coarsely vesiculated spongy surface modified 

 by flow tractions so as to resemble patterns of complicated lacework. 



