Cretaceous Stratigraphy of Lower Murchison River Area, 31 
Western Australia. 
bedded layers being- either whitish or brown. This transitu)n zone was only 
seen well in a few ])laceSj e.g‘, in the Pillarawa section and at Second Gulb/ 
Point, where it is aiiproxiiuately tio feet thick. In many ])laces detritus 
derived from the rather incoherent overlying Butte Sandstone conceals the 
higher part of the Tuinblagoodu Saruistone. At Tmnblagooda Hill itself 
the upper part of the sandstones is well exposed and here includes a 20-foot 
band of rather massive l)rov'nish. strongly cross-bedded sandstone which is 
intercalated in the well-bedded series, and makes the transition zone at least 
60 feet thick in this ]dace. 
The sandstones exposed east of ^It. Curious, in the up])er reaches of 
Bungal)andy Creek and in the vicinity of Warranjababba Spring are fine- 
grained and thin bedded and cross-tx'dding is not much in evidence. It is 
at present impossible to say whether these are exjiosures of the normal facies 
of the top section of the Tumblagooda Sandstone, or Avhether a change in 
the character of tlie whole formation takes place in an eastwaial direction. 
Fossils . — The only fossils in this sandstone are invertelirate tracks and 
vertical burrows. The latter are iiarlicularly prominent and occur at many 
horizons throughout the entire secjiumce. Tliey were observed in more detail 
in the vicinity of “Stone Wall’’ at the foot of Toohmga Iknnt, in the out- 
crops below the cliffs between Tliirindine and Toolonga, in Second Gully, 
and in the Tumblagooda Tlill s(‘ction where several horizons with man}- bur- 
roAvs were seen. The burrows now form eyliuders wliicdi arc either filled 
Avith sandstone of a different colour from that of the surrounding rock, (for 
example they may consist of red sandstone penetrating laminated red and 
Avhite rock), or are merely made evident on cliff sides by rlifferential Aveathor- 
ing. They are always vertical and g(merally have a diameter of one half 
to one inch, although diameters up to two inches have hovn obstwved. They 
may be up to eight inches long, Init are mostly shorter. They are generally 
restricted to sandstone layei*s Avhich are tAA'o to four feet thick, and there 
is usually a considerable thickness, rarely less than 20 feet, bet\A'een suc- 
cessive burroAv horizons. 
\ 
The burrows are frequently rather crowded: in one horizon in the 
Tumblagooda Hill section 100 burrows were counted on a surface measuring 
50 X 50 cm. On the bedding planes the place of a burrow is indicated by 
a little mound. 
Invertebrate tracks along bedding planes have been observed only in one 
locality, a low hill east of Tutula Avindmill where the inclined bedding planes 
of the cross-bedded sandstone are densely covered Avith meandei'ing trails 
which are six to eight mm. wide and stand out in low relief above the bed- 
ding plane; they are characterized by a sharp furrow in the middle and may 
have been made by gastropods. 
Thickness . — Since the base of this sandstone has not been discovered its 
true thickness cannot be stated. The plateau level on the south-east side of 
the river is about 400 feet above the sea and this may be taken as the 
approximate maximum exi)Osed thickness in the area of our investigations. 
This, hoAvever, must be taken as a minimum figure, for l)y extending the 
survey towards the south-east a somewhat greater thickness would probably 
be obtained. 
