FLANGES OF AUSTRALITES (TEKTITES) 11 
flanges are quite alike, a statement substantiated by this investi- 
gation. 
Typical cross sections of flanges are indicated in Fig. 2, c to x, 
and a few examples were figured by Dunn (1912 b) and by Baker 
(1937). In Fig. 2, sketches a to n are arranged in an order which 
the author thinks may represent stages in development from rims 
of lenses (Fig. 2, a and b) through more common shapes to rare 
types (Fig. 2, o to t). 
Fig. 2 a is a radial section of a lens with rim well marked on one 
side only, and Fig. 2 b a radial section of a lens with a sharply 
marked equatorial rim. In Fig. 2 c, a longitudinal section of an 
oval, the projection is intermediate between a rim and a flange. 
In Fig. 2 d, a longitudinal section of a canoe, the flange-like 
structure is further drawn out and commencing to curve 
posteriorly. Fig. 2 e, an oval, has a small flange partially curved 
towards the posterior surface of the core. The rare type illustrated 
in Fig. 2 f occurs on a few flat-topped buttons and on several 
dumb-bells and teardrops; it has a smooth rounded outer edge 
and marked flow ridges, and is inclined at 60° to the central core. 
Fig. 2 g, a cross section of the flange of a button, has a vertical 
neck and a flat posterior surface inclined at 20° from the 
horizontal and the gap (a in Fig. 1) is becoming conspicuous; 
button-shaped australites from Mulka, South Australia, commonly 
have flanges of this type, but at Port Campbell only certain boat- 
shaped specimens have such flanges. 
Fig. 2, h and i, flanges of buttons, illustrate convex posterior 
surfaces partially overlapping towards the core, and Fig. 2, j to r, 
show further stages of rearward curvature but may not represent 
a definite series of stages. Overlapping may reach a stage where 
the contact between flange and core is completely obscured from 
above. 
Fig. 2 s, a radial section of an oval, plate-shaped australite (plan 
like that of Fig. 2x) shows a thin, flat horizontal flange with 
shallow depressions between the centre and the outer edges of the 
anterior surface. In Fig. 2 1, a radial section of a flat, disc-shaped 
australite (plan like that of Fig. 2 w), the flange overlaps a thin 
central core. Fig. 2 u, plan and side aspect of a detached flange, 
shows that the width of the flange is considerably less than the 
diameter of the area once occupied by the core. Fig. 2 v is a flange 
fragment with a smooth inner edge and adjacent flow lines, and 
a crenulate outer edge. In Fig. 2 w, a disc, the flange is broad in 
proportion to the core and has concentric flow lines near its outer 
edge. In Fig. 2 x, the posterior surface of an oval, plate-shaped 
