Thk and Physiography of thh \\\)ngono-Cardup Aiuoa. 2()7 
1. Ihc W ongotHj Brook. — This is tho ninjor slrojuu. 4’lu* P-shn]>C)l 
bond in tho Wonj^'on^' at'tor it (nitors the aren suii'^^ests tlu' larger rpature 
observed in ihe (dinning- Kiver ((Tarke and Williams, 192(), ]>. Ui-t) and 
likewise* may lie a reiie- ot' an old nor( h-soiith drainage ehannel. This is 
suggested by tlie alignment of tribu(ari(‘s witii the* straight eastern side' of 
the bend and with the early-mature* valley of a sonth-llowing tributary ol^ 
the J^ee'iiyup Brook, a little over a. mile* to the south. West of tlii;. b(*mP 
the AVongong Hows for a (|narter of a mile in a vewy juveaiile vall/\ with 
walls rising steeply to 5t)t) feet above the stivam. Here the* trihutaries are 
she^rt, stee*p and inseepuait. n(.>wnstre*am the* brook swings we*st-north-west 
into a broaeler valley: at the bend, a sliort e-haiim*! has b(*e'n abandone'el. The 
course is genily winding and e'onlains a little alluvium; it ree-e'ive's se'veral 
tributarie's and then passes through the foothill zone onto the ]>laiu. 
2. The BeeugHp and Cardop Brooks, — These* have yemng \'alleys whie'h 
lack the* gorge-likt* cliarae-ti't istics of the Wongong ami posse'ss st(‘e'pe*r gi-aeles. 
These dirrer<*nc(*s nmy be- (‘Xphnne'd by cemsidering the* ipipe-r porliem of the* 
Wongong, east of the ar(*a. This can be ivgareled, like* tin* upper llede'iia 
and ( anniug I\i\'ers, as another example* oi a e'onse'eiue'ut semth-(*asli*rly 
bowing stream wliiedi elevelojied afte*r the uplift of the Darling Pe*neplaiii, 
and w’Hs ('a])ture'd and revei’se'd by a more active* we'stward flowing e‘e)useiim‘nl 
stream (dutsoii, UIdd, p. Kid). Probably the (hre'e b]-oe)ks we*re* de'veloix'd 
('■({ually as we'stward (lowing conse(]ue‘nts, Imt the* young Wongong, bee-ause^ 
it had a shorter distan<*(' io advaiu'e by lu'aehvard e're)sion, reaclu'd flu* semth- 
east stream. This le‘d to auginente‘d How ami de'e'peming e)f the* vall(*y. Mean- 
while the* Beenyup and (dardiip Brooks el(*veh)p(*d I libutarie's, hut la'taiiu'd 
re*lati\'(‘ly st(‘e]'> graeles. 
3. Minor tribiifaries io the main stream comprise*: — 
(a) I nceu’tain i'(*li(-s of a mature norlh-se>utli system. 
(b) Shen-t st(*(‘p-grad('d minor stivams whie-h ge-m-rally enter at 
I'ight angles to the* main str(*am. 
(c) Lai’ge*}* tributai’i(‘s which temd to be de*ve'lo|)ed m‘ar the scarp;. 
the* N'alle'vs are* ye)uthful, but some* bre)!ulen in tlie u]>j>er 
parts. Small wateidalls oi‘te‘n etccui* at an eIe*vation of dtIO 
to 450 f(*et. 
4. Independent sear}) streams. — The*se* have* steep graele*s and He>w west. 
Ttxamph's are* the* twe) creeks iu)i-th e>f tlie* Byfeerel Brickworks ((luarry. 
5. Adjastment of fo})ogra})hif to geologip — Adjustment eif the drainage 
to the major i-ock sti-ucture* is not ap|)ar(*nl,. The* course's of the* thre*e main 
brooks form arcs, slightly e-oncave^ lei the north which cut- ae-ross the* strike* 
of the gneiss and the* s(*dim(*n(s. Two tributarie's of tho Beenyup Bre>ok 
appear to have* be-en iiiHue'iice'd iiy (piartz blows trending north-W(*st, 
Between the Wongong and Beenyup Broeiks, stre'ams have de‘ei)ly 
eunbayed the* late'i’ite capping by he*aelward erosion, le*a\'ing a iiumbe*!- of largev 
spurs, some* ove'rlying large e])idie>rite dyke's. Thc'se* spurs represe'iit tlie* 
most westerly extension of (he high leve*] latei'ite. The sharp edge* of the 
latei-ite disa]>pears where the* matui’e lu'arls of the creeks approach it and 
laterite pe'bbles and sand slo])o gently u)) to the laterite* love*!. Tn such 
places soaks may de*veh)p, the^ water appare'iitly coming from under the> 
laterite cap|)ing. 
