Scars at Kilauea — Wentworth 
365 
The impact scars are outlined by rings, gen- 
erally 2 to 12 feet in diameter (Fig. 3). A few 
are as much as 20 feet across. The rings 
consist in part of coarser fragments ranging 
up to 6- or 8-inch blocks and are conspicuous 
because of the lag effect whereby associated 
finer material has been blown and washed 
away. Within each ring is a central depression 
a few inches to one or two feet deep, with a 
surface of finer silt which has washed in from 
the surrounding ring (Fig. 4). In many of the 
rings the silt of the central depression has a 
slightly cemented crust due to drying out of 
capillary moisture, in common with most of 
the surface of the ash terrane. The general 
appearance of the rings, where they are closely 
spaced, resembles poly gonboden, but the sim- 
ilarity is certainly superficial and is due to lag 
processes rather than to frost (Fig. 5). 
The larger rings often retain the blocks that 
apparently caused them, or the block respons- 
ible can often be identified with confidence a 
few feet beyond (Figs. 6 and 7). There is a 
preponderance of indicated flight directions 
stemming from the vicinity, roughly, of the 
present Halemaumau. Some of the blocks 
have broken on landing, as also have some of 
those of the 1924 series. 
Many of the rings are marked by one or 
more small trees or shrubs which have taken 
Fig. 2. Sketch map showing the southern part of the caldera of Kileauea and distribution (stippled area) of 
the impact scars here described. 
