Fossil Flora from Pagan — Fosberg AND CORWIN 
5 
erally grassland with scattered trees or clumps 
of trees. The trees may be Fandanus , Casuarina , 
or any of a number of broad-leafed species. 
Many of these areas were under cultivation 
before World War II and are weedy and have 
rows of Casuarina and other trees planted by 
the Japanese as windbreaks. Jatropha gossypi- 
folia L., a fleshy-stemmed shrub introduced 
by the Japanese in the 1930’s, has spread and 
now dominates large areas in the central part 
of the island. Clumps of trees of various kinds 
mark the sites of houses, still existing or not. 
On the gently sloping northwest part of the 
island is a large coconut plantation. There are 
smaller ones in many parts of the island, both 
on plains and on talus cones. Coconuts are 
also common in ravine mouths and on steep 
slopes above the sea. The large plantations 
are of relatively recent date, but there is no 
way of knowing the age of smaller clumps of 
coconuts that are mixed with other vegetation 
on various parts of the island. Some may very 
well date from before European visits to the 
island. 
FOSSIL LOCALITIES 
All samples of plant impressions are from 
the northern half of the island, mostly from 
tuff of the pre-caldera succession. Impres- 
sions were noted in talus blocks at the foot 
of a high cliff at the south end of the island 
but no specimens were obtained. One sample 
(PC-86) was collected from post-caldera tuffs 
forming the surface of a terrace northeast of 
the bisected tuff cone; other impressions in 
post-caldera deposits were observed on the 
uplands east of the cone. 
Samples from the pre-caldera succession 
represent several stratigraphic horizons (Table 
1). Most collections are from tuffs that under- 
lie or are included in an extensive tuff-breccia 
sequence near the top of the succession. One 
of the most accessible localities (PC-43) is at 
a sharp bend in the trail at the west end of the 
caldera rim. Three samples (PC-58, PC-79, 
PT-7) are from tuffs associated with lavas or 
volcanic breccias that underlie the upper 
breccias. 
Impressions of tree trunks were observed 
near the base of the upper breccias at several 
places (Fig. 2). In all cases the impressions 
are nearly horizontal and therefore represent 
fallen branches and trunks. Many are oriented 
about parallel to radii from Mt. Pagan, sug- 
gesting that a powerful explosion from the 
mountain felled the trees. 
THE FOSSIL PLANTS 
Almost the entire collection consists of leaf 
impressions, most of them fragmentary. Some 
of these have no features preserved that would 
make possible even tentative determinations. 
Very careful scrutiny shows that in the entire 
Fig. 2. Tuff overlying lava and underlying tuff- 
breccia at the west end of the caldera rim. Plant im- 
pressions were collected from the tuff below and 
interbedded with the dark colored cindery layers in the 
upper part of the picture. The hole in the cindery layer 
was probably formed by decay of a tree trunk that had 
been buried by the ash. The sides of similar holes 
elsewhere commonly retain impressions of tree bark. 
A deformed tuff layer near the center of the picture 
may represent the soil horizon in which the plants 
grew. 
