JOURNAL OF 
THE 

ROYAL 

SOCIETY 

OF 

WESTERN 

AUSTRALIA 


Volmne 72 V Fart 3 • 1990 ^ 


ISSN 0035-922X 


The Royal Society of Western Australia 


To promote and foster science in Western Australia 
and counteract the effects of specialization 


PATRON 


Her Majesty the Queen 


VICE-PATRON 


His Excellency the Governor 
of Western Australia 


COUNCIL 1989-90 


President 

Vice-President 

Past President 
Joint Hon Secretaries 


Hon Treasurer 
Hon Librarian 
Hon Editor 
Hon Journal Manager 
Members 


M Candy BSc MSc FRAS 

B Dell BSc (Hons) PhD 
K McNamara BSc (Hons) PhD 

J S Pate PhD DSc FAA FRS 

J R Gozzard BSc (Hons) 

W A Cowling B Agric Sc (Hons) PhD 
L N Thomas BSc MSc 


J Dodd BA MSc PhD 
M A Triffitt BA ALA A 


1 Abbott BSc (Hons) PhD 
P Birch BSc Dip Comp 

L E Koch BSc MSc PhD 

J S Beard BSc MA D Phil 
V Semeniuk BSc (Hons) PhD 
P Playford BSc PhD 
J Fox BSc MSS MSc PhD 
D Walker BSc D Phil 


Journal of the Royal Society of Western Australia 72 (3), 1990, 63-66 


Mortality and growth of tree species under stress at 
Lake Toolibin in the Western Australian Wheatbelt 


David T Bell & Raymond H Froend 


Department of Botany, The University of Western Australia 
Nedlands WA 6009 


Manuscript received June 1988: accepted December 1988 


Abstract 

Tree species occupying the bed and margins of Lake Toolibin, an ephemeral lake of the Northern 
Arthur River system in the central Western Australian Wheatbelt, were permanentiv marked in 1983 
and then remeasured after 5 years to determined survival, growth and vigour. Trees of the lake margins, 
Eucali/ptus ruiiis and Melaleuca stroiwphylla, showed the greatest mortality, greatest reduction in vigour 
classification and smallest growth increments to the environmental conditions of the lake now being af- 
fected by secondary salinisation. The upland species. Acacia acumitiota and Ailocasuaritia huegeliatta, 
also showed elevated levels of mortality and reduced vigour, but had the highest annual grow-th in- 
crements of the species measured. Casuarina obesa populations in the more safine areas of the lake en- 
vironment showed increased mortalities, decreased vigour and reduced growth compared to the trees 
of areas of the lake environment with more favourable conditions. 


Introduction 

Lake Toolibin (32°56'S, 1 17®1 1'E) is one of the few com- 
paratively fresh water lakes in the central Western Aus- 
tralian Wheatbelt and one of particular importance as a 
waterfowl breeding location. Tne lake lies at the head of 
the chain of shallow ephemeral lakes of the Northern 
Arthur River, a tributary of the Blackwood River System, in 
the Wickepin Shire. All other lakes of the Arthur River Sys- 
tem have oeen severely affected by secondary salinization 
and the Shire has lost more than 3% of its formerly arable 
land to the effects of increased salinity and flooding 
(NARWRC 1978). 

Lake Toolibin and its surrounds, incorporated in Re- 
serves 27286 and 9617, have been intensively monitored 
since the impacts of secondary salinization were first no- 
ticed in the early 1970s (NAAWRC 1978). Currently the 
Department of Conservation and Land Management is en- 
gaged in a tree planting and groundwater pumping oper- 
ation to restrict the further decline of this important region 
of indigenous flora and fauna. 

Detailed mapping of topographical, environmental and 
vegetational features revealed patterns of plant com- 
munity distribution and relative nealth and vigour of the 
communities in relation to the input of salinity from the 

A69349-1 ^3 


several drainage systems (h’roend et al 1987). Casuaritia 
obesa dominates the seasonally inundated lake bed. 
Melaleuca strobophiflla occurs on slightly raised sections of 
the lake floor and Eucalyptus ruiiis can be found along the 
margins of the lake and inlet drains. Upland areas around 
the fake are dominated by open woodlands of Eucalyptus 
loxophleba, Ailocasuaritia hue^cliaiia and Acacia 
acuminata. 

Study of the patterns of tree deaths in the lake environ- 
ment has indicated that the increasing salinity levels have 
adversely affected the populations of Casuarina obesa and 
Melaleuca strobophylla while both increased salinity and 
prolonged inundation have affected Eivcij/i/p/iiS nidis 
(Froend el al 1987). The current study reports bn the mor- 
tality, change in tree vigour and incremental growth 
achieved in permanently marked populations from 1983 to 
1988. 

Methods 

Five study areas wore established during the Autumn of 
1983 in and around Lake Toolibin. All trees were tagged at 
breast height with a permanent aluminium tag, mapped, 
measured for diameter and subjectively scorecT for vigour 
(0 healthy to 9 - dead). The elevation of each tree in re- 
lation to lake levels was determined in Autumn, 1983. 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Although it is realized that soil salinity levels vary greatly 
with season, the 1983 data on the percentage of the dry soil 
weight as NaCl contribute some indication of the severity 
of each study area (Table 1). 

Table 1 


Features of the tagged tree plots 
(After Froend et al 1987). 


Area 1 A transect of four plots (each i 20jti X 20m) grading from the we^tern 
upland of the Northern Arthur River channel dominated by £iua/w/'Mis 
loxophU’ha across the Caiuanua ehi'ca - dominated fIcHKiplain and up into 
the eastern upland wixxlland. All elevation are above mean lake level 
Salinitv levels in March 1983 ranged between 0.04 % NaCl in the uplands 
to 0-1-1 % in the heavy soils near the channel margin 


Area 2 A transect of 3 plots grading from upland £. Aiflcin 

acufittiiiUa wcHxtIand into the lake basin region dominated bv Ca-ntanna 
on the eastern margin of the lake where water conditions tended to 
be fresher Salt concentrations in ihe upland were low at 0 04 % NaCl. 
Some lake bed sections in this area reached 0 12% NaCl in March 1983 


Area 3 A liKation of 4 plots on the western i*dge of the lake (usi south of the 
Western Drain. Ihe source of a major input of salts and the major region 
of tree damage in 1983. Uppi*r reaches are dcmunateii bv iiiiii/i/t»/ii.< rutiiy 
with CrtsHflrnm ohesa and Afcfa/ciica in the lake Ksl jHirtions 

of the area Mean soil salinitv levels reached 0..30 % NaCl, 


Area 4 A relatively flat region in the central part of the lake basin harbouring 
a monoculture stand of af'rsii some 300 m east of Site 3 The two 

plots had a mean soil salinitv of about 0.07% NaCl Inundation j’^rcent 
ages were the highest of the siudv sites due the central hasin Unalion 

Area 5 A single plot site located in the Northwest Creek drainage, an area of 
moderate input of salinity. This plot was not analysed for soil salinitic*s in 
1983. The major species of the lowlying area was Crtsiurrma e/vsfl with t 
riidts in marginally higher sections of the area. 


In May 1988, all trees were remeasured for diameter at 
breast height with diameter tapes and again scored for vig- 
our class. The permanent tag at breast height ensured that 
the measurements were taken at the same circumference of 
the tree as previously. The percentage mortality of trees 
and change in diameter and vigour for all species, except 
Casuarina obesa, were determined by combining the data 
tor alt sites, bulficient numbers ot Lasuantia obesa allowed 
comparisons of the several locations within the lake en- 
vironment on the mortality, vigour and growth. 


Results 

The two common lake bed/lake rnargin species, 
Melaleuca strohophiflla and Eucalyptus rudis, snowed rela- 
tively high mortality rates with nearly a Quarter of the 
tagged trees dying in the 1983-1988 period (table 2). Mor- 
tality was also relatively high in the upland species Acacia 
acuminata and Allocasuarina hueseliana, however, mor- 
tality was nil in Eucalyptus loxophleba. Change in vigour 
class mirrored the mortality percentages with Melaleuca 
sfrof>op/iy//(J showing the greate.st mean change in vigour 
and Eucalyptus loxopttlcba showing the least change in vig- 
our over the five year period. The separate population cal- 
culations of mortality, vigour and growth in Casuarina 
obesa revealed that mortality was highest at the midlake re- 
gion (area 4), but in general most trees tagged in 1983 sur- 
vived until the resample period of 1988 (Table 3). Trees of 
the lake bottom near me eastern perimeter at area 2 
showed the greatest change in vigour, a reduction of more 
than 4 units in the 5 years. Total growth increment was 
smallest in the trees of the midlake site (area 4) and the lake 
bottom trees growing on the western edge of the lake (area 
2), but the growth rates of Casuarina obesa at some of the 
other sites were comparable to those tree species growing 
in the apparently more favourable habitats above the lake 
margin. 


Table 2 

Percentage mortality, change in vigour class and increment growth of tree species of 

Lake Toolibin, Western Australia 

Values are means ± standard deviations. The annual increment was determined as one-fifth of 

the 5 year change in diameter 


Species 

N 

Mortality 

% 

Change in 
Vigour 

Growth Increment (cm) 
1983-1988 Annual 

Acacia acuminata 

14 

21 

-2.0 ± 1.8 

2.34 ± 2.09 

0.47 

Allocasuarina huegeliaiia 

8 

25 

-1.7 ± 1.4 

1.90 ± 2.16 

0.38 

Eucalyptus loxophleba 

14 

0 

-0.7 ± 0.7 

1.02 ± 0.75 

0.20 

E. rudis 

16 

25 

-1.7 ± 2.7 

0.32 * 1.00 

0.06 

Melaleuca strobophylla 

15 

27 

-4.4 ± 2.7 

0.47 ± 1.07 

0.09 


64 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Table 3 

Percentage mortality, change in vigour class and increment growth ( • sd) of Casuaritia obesu populations growing 

on the bed of Lake Toolibin, Western Australia 


Area 

N 

Mortality 

% 

Change in 

Vigour 

Growth Increment (cm) 
1983-1988 Annual 

1 

39 

10 

-2.0 ± 1.7 

1.26 ± 1.14 

0.25 

2 

22 

0 

-3.7 ± 4.0 

0.80 ± 0.91 

0.16 

3 

23 

4 

-0.2 * 1.7 

1.34 ± 1.06 

0.27 

4 

87 

17 

-1.6 ± 1.3 

0.44 ± 0.44 

0.09 

5 

17 

0 

-0.8 ± 0.8 

1.44 ± 0.62 

0.29 


Discussion 

Species commonly occupying regions of annual flooding 
have a high tolerance of saturated soil conditions (Pereira 
& Kozlovvski 1977) and often can tolerate considerable in* 
crease in flooding duration before death occurs (Green 
1947). Several years of permanent inundation are required 
to cause death in sucn species (Yeager 1949, EggWr & 
Moore 1961). 

The tolerance of river bottom or ephemeral lake species 
to the combined stresses of increased flooding durations 
and increased salinity, however, has not been nreviously 
recorded. Australia is somewhat unique in that tne clearing 
of large tracts of woodland is now resulting in the com- 
bined stresses of increased waterlogging durations and 
higher levels of soil salinity occurring in catchment dis- 
charge areas (Nulsen 1986)/The response of the vegetation 
in the Lake Toolibin region to secondary salinization 
seems to have been one of greater effect on the lake margin 
species than those inhabiting the environments of the lake 
bottom or the upland regions unaffected by inundation. 
Casuarina obesa nas been shown to be highiv tolerant of 
salinity and waterlogging stresses (van der Moezel ef ol 
1988). Although areas of high C mortality exist, over 
the majority of the lake bed the increase in stress appar- 
ently still lies within the limits of tolerance for the mature 
C obesa trees. In Melaleuca stroboph}^lla and Eucalyptus 
ruiiis, however, the longer penc»ds of saturated soil profiles 
induced by the clearing of upland recharge zones of the 
catchments and the increased levels of groundwater sal- 
inity have combined to stress individuals of these two 
species to the point of mortality. nuiis has been 

previously shown to be adversely affected bv increasing 
periods of soil saturation (Froend cl al 1987). Certain 
species of Melaleuca, for example, M. acacioides (Barlow 
1986) and M. styphelioides (Midgley ct al 1986), show toler- 
ance to soil salinity, but no studies on A4. strobophylla have 
been carried out to indicate suspected abilities to tolerate 
increasing levels of flooding conditions or groundwater 
salinity. The present study indicates that these species ap- 


pear sensitive to secondarv salinization and require careful 
monitoring in the future for further degradation of stream 
courses in the central Wheatbelt. 

The mortality of the upland species is more difficult to 
explain. Remnant woodlots in rural areas of Australia have 
reputedly suffered large tree population losses since the 
late 1960s and early 1970s. This decline in rural tree popu- 
lations is probably due to several reasons. The first, loss 
due to removal of trees as part of farm management, and 
the second, due to old age, coupled with a paucity of re- 
cruitment of tree seedlings because of active suppression, 
grazing and competition with improved pastures, are eas- 
ily understood reasons for rural tree population decline. In 
the present study deaths in Acacia acummata. Allocasuariua 
huej^eliana and Eucalyittus nidis occurred in reasonably 
large trees but it would be difficult to conclude that all 
deaths w'ere due to old age. A third element, "rural 
dieback", the premature and relatively rapid decline and 
death of native trees on farms, is apparently a consequence 
of interacting environmental stresses and remains largely 
unexplained (Old et al 1981). It is apparent, however, that 
remnant woodlands in rural landscapes represent 
ecosystems w^hich are precariously balanced (Wylie & 
Lanasberg 1987). Rural w'oodlands have little chance of 
survival unless supplemented by replanting or by natural 
regeneration. The clata of the present study further docu- 
ment this phenomenon, but provide no clues to its cause. 

The efforts of the Department of Conservation and Land 
Management to reafforest the upland margins of the Lake 
Toolibin reserves and the pumping of saline groundw’aters 
from the lake basin environment should provide a more 
favourable habitat for the present population of trees and 
encourage natural recruitment. The Lake Toolibin reserves 
would be a logical location to establish a more extensive 
series of plots to study seedling recruitment and mortality 
and crow'n condition oy age class of each major species of 
the area. Hopefully the patterns of poor survival, aeclinc in 
vigour and siow growth rates recorded during the past five 
year period will be reversed in the future. 


65 


Journal of the Royal Society of Western Australia 72 (3), 1990 


References 


Biirknv B A 1986 Contributions to a revision of Mchlciua (Myrtnceoe); 13. 
Brunonia 9; 163- 177. 

W A & Moore W B 1961 The vegetation of l-ake Chicot, l.ouisiana, after 
eighteen vears of impoundment. Southw€*st Nat 6:175-183. 

1 nH*nd R H. Heddle E M, Bell D T & McComb A J 1987 Effects of salinity and 
vvaterlc^ing on the vegetation of Lake Toolibin, Western Australia. 
Aust j ^ol 12:281-298. 

Crec*n W E 1947 Effects of water imixmndment on tree mortality and growth. 

I For 45 1 18-120- 

Midglev S I, Turnbull | V\‘ & Hartney V j 1986 Fuel- wood speiies for salt affec- 
ted sites. Reclam Reveg Res 5:285-303. 

Northern Arthur River Wetlands Rehabilitation Committee (NARWRC) 1978 
Progress Report. Unpublished report to the State Minister of l'isherit*s 
and Wildlife. 


Nulson R A 1986 Management to impn>ve production from salt affected soils 
Reclam Reveg Res 5:197 2^9. 

Old K M, Kile C A & Ohmart C P 1981 Eucalvpt Dieback in lori‘sls and 
WtH»dlands. CSIRO, Melbt'urne. 

Pereira ] S is Ko/.lowski F T 1977 Variations amongst w<hx1v angiosperms in 
relation to flcioiling. Physiol Plant 41:184-192. 

van di^r Moe/el P C. WatMin 1. E, Pearce-Pinlo C V N & Bidl D T 1988 The re- 
sponse of SIX £Mcii/i//>tus specii*s and CH'yiiatina iifnsrt to the combined 
effect of salinity and waterlogging. Aust 1 Plant Phvsiol 
15 465 474 

Wylie I R is I andsberg | 1987 The impact of in*e dcxline on remnant wtHnllots 
on farms. In Nature Conservation. The Role of Remnants of Native 
Vegetation (eds D A Saunders. G W Arnold, A A Burbidge & A J M 
Hopkins). Sum‘v Beattv is Sons, Chipping Norton, New South 
Wales. 331-332- 

Yeager I. E 1949 Effect of )H*rmanent flwding in a river-bottom timber area. 
Buit Illinois Natur Hist Surv 25:33-65. 


66 


Journal of the Royal Society of Western Australia 72 (3), 1990, 67-74 


Motor vehicle emission inventory for the Perth airshed 

T J Lyons, R O Pitts, J A Blockley, 

J R Kenworthy & P W G Newman 


Environmental Science, 

School of Biological and Environmental Sciences, 

Murdoch University, Murdoch WA 6150 

Muuuscrtpt received July 1988: accepted December 1988 

Abstract 

A motor vehicle emission inventory is developed for the Perth metropolitan airshed by integrating 
data on traffic flow conditions with emission factors that incorporate the effects of both speed and accel- 
eration. This highlights the impact of varying driving conditions on the spatial and temporal resolution 
of vehicle emissions, and illustrates that traffic congestion enhances pollutant production through in- 
creased variations in vehicle accelerations 


Introduction 

Air quality within Perth is for most days of the year ex- 
ceptionally clean when compared to cities of comparable 
size (Bottomley & Caltell 1974, Lax cf al 1986). However 
under suitable meteorological conditions pollution events 
can occur that exceed the USA primary and secondary 
standards (Bottomley & Cattell 1974, KAMS 1982). These 
are generally associated with light stable synoptic pressure 
gradients ("Bottomley & Caltell 1974) or mesoscale 
phenomena, such as the sea breeze (KAMS 1982) 

With Perth, the emission of gaseous pollutants is con- 
fined to two major sources; an industrial area concentrated 
to the southwest of the metropolitan area and motor ve- 
hicles within the region (Lax et al 1986). The Kwinana in- 
dustrial area emits large quantities of SO, and to a lesser 
extent NO^ (KAMS 1982). These emissions have been 
modelled under both stable conditions (Kamsl & Lyons 
1982) and sea breeze fumigation (KAMS 1982), as well as 
in a standard climatological model based on Gaussian 
techniques (KAMS 1982). In all cases, the models applied 
to the immediate region surrounding Kwinana and aid not 
attempt to incorporate the broader airshed concept. 

An analysis of the air quality across the broader metro- 
politan airshed requires ine estimation of the other major 
source outside the industrial area, motor vehicles. These 
are the source of oxides of nitrogen (NO^), brake lining 
dust, hydrocarbons (HC), carbon monoxide (CO), smoke, 
aldehydes, lead salts and partide.s, rubber, gaseous petrol 
and carbon particles (Lay 1984). All of the CO and NO^ are 
emitted from the exhaust pipe whereas approximately 
50% of the HC's from an uncontrolled vehicle are emitted 
via the exhaust, with the remainder coming from the 
crankcase, carburetor and fuel tank vents (SPCC 1980). 


Evaporative emissions result from the fuel system 
leaking HC's to the atmosphere at a rate determined by the 
temperature of the system (diurnal emissions) and hot soak 
emissions occuring after the vehicle has been driven some 
distance, through heating of the carburetor and fuel lines 
(Nelson 1981). Hamilton et al (1982) estimated evaporat- 
ive emissions from typical early 1970's vehicles as 
O.Sgkm ' and noted that these are generally constant 
through the life of the vehicle. Subsequent to 1975, Aus- 
tralian emission standards (Table 1) have resulted in im- 
proved pollution control, as evidenced by Nelson (1981). 
He confirmed diurnal evaporative emission factors of 
22.1 g vehicle ' day • for uncontrolled (pre 1975), and 5.1 g 
vehicle ' day ’ for controlled vehicles, respectively, with 
hot soak emissions of 12.5 g vehicle * for uncontrolled, and 
4.2 g vehicle ' for controlled vehicles. Consequently, evap- 
orative emissions are a function of the age of the fleet 
whereas exhaust emissions are also depenoent on vehicle 
driving characteristics. Hence the spatial and temporal 
variation of emission source strength is dependant on driv- 
ing chracteristics across the airshed as well as the age mix 
of the fleet. 

Table 1 


Australian emission standards, g km'L 
(after SPCC 1980) 


Date of Manufacture 


After 

After 


1 July 1976 

1 January 1981 

CO 

24.2 

18.6 

HC 

2.1 

1.75 

NO, 

1.9 

1.9 


67 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Vehicle emissions in Sydney were estimated by Stewart 
et al 1982 from the product of vehicle kilometres travelled 
(VKT), emissions per kilometre for each model year and 
travel fraction done by each model year. Although this 
gives a bulk estimate across the airshed it does not allow 
for the spatial resolution of the sources nor does it account 
for variations in driving conditions. 

From a preliminary dynamometer test of 28 vehicles, 
Kent & Mudford (1979) found that typical emissions under 
Australian urban driving conditions, at that time, could be 
expressed as: 

[CO] - 465s'0 ''7 
[HC] = 21.5s-‘'=' 3 
[NO^ - 2-2 ^ 0.008s 

where [CO] is the carbon monoxide emission (g km ‘), 
[HC] hydrocarbon emission (g km '), [NOJ oxides of nitro- 
gen emission (g km *) and s the average vehicle speed 
(km h '). These are of a similar form to the estimates used 
bv Iverach et al (1976), based on US experience, and equiv- 
alent to the values employed by Taylor & Anderson ( 1 982). 

Such an estimation assumes emissions can be rep- 
resented in terms of average speed alone and neglects the 
influence of variations in driving conditions, particularly 
changes in acceleration, on emissions. For example, Kent ii 
Mudford (1979) found that a three dimensional plot of 
emission rates against speed and acceleration led to para- 
bolic surfaces for CO and HC's, w'hile NO^ showed a gen- 


eral increase in emission rates with speed and acceleration. 
In particular, they found that both CO and NO^ show 
marked increases in emission rale with positive acceler- 
ation. This cannot be accounted for from an average speed 
model and highlights the need to incorporate a wide range 
of accelerations and speeds to produce reasonably rep- 
resentative emission inventories. 

Thus the spatial resolution of these emissions requires 
an integration of data concerning traffic flow character- 
istics with data on vehicle numbers, vehicle types and 
VKT- Previous work in this area has emphasized the latter 
data on vehicles and has lacked any detailed input about 
how those vehicles are being driven (SATS 1974, Visalli 
1981). A very basic approach to incorporate driving pat- 
terns has been attempted for Melbourne but uses only the 
standard Los Angeles driving cycle for its traffic character- 
istics (Neylon & Collins 1982). 

Hence this paper addresses the development of a motor 
vehicle emissions inventor)' for the Perth urban area based 
on actual driving pattern data across the urban area as well 
as vehicle emission data resolved on the basis of speed and 
acceleration. Pollutant source strengths are expressed as 
the total emission averaged over a specified time period 
and a specified grid square of the airshed. 

Methodology 

Kenw'orthy et al (1983) used an urban ecological ap- 
proach in treating the city as an integrated system, to ob- 
tain representative driving cycles across Perth. They div- 


Table 2 


A summary description of the six driving pattern areas in terms of the major factors used to derive them (after 
Kenworthy et a! 1983). Note all rankings of characteristics are made relative to the mean of Perth. 


Characteristics 

Area 

Social Economic Status 
of Residents 
(Household income and 
vehicle ownership) 

Activity 

Intensity of area 
(land use intensity, 
congestion, public 
transport availability) 

Dominant modal split 
features of residents 

Central Core 

Area 1 

Very low 

Very high 

Peak periods 

Very low private vehicle 
usage, very high public 
transport, walking and 
biking 

Inner suburbs 

Area 2 

Average to low 

High 

All periods 

Very high public transport 

Middle Western suburbs 

Area 3 

Average to high 

Average to high 

Off peak 

Very low public transport 
usage 

Middle South, outer North 
and 

Eastern suburbs 

Area 4 

High 

Low 

Peak periods 

High private vehicle usage, 
low public transport, walking 
and biking 

Outer South East and North 
East suburbs 

Area 5 

Average 

Very low 

Off peak 

Very high private vehicle 
usage, very low walking and 
biking 

Northern State Housing 
suburbs 

Area 6 

Low 

Average to low 

Off peak 

Very low private vehicle 
usage, very high walking and 
biking 


68 


Journal of the Royal Society of Western Australia 72 (3), 1990 


ided the metropolitan area into six regions characterized in 
terms of socio-economic status and activity intensity 
(Table 2), and using the chase car technique (Scott Re- 
search Laboratories 1971) obtained detailed second by sec- 
ond speed time histories of typical urban driving in each of 
these regions. Although statistically representative driving 
cycles can be generated from such data, they suffer a con- 
siderable loss in speed resolution (Lyons et al (1986). 
Hence, Ken worthy (’/ al (1983) obtained representative 
driving cycles for each region by matching summary 
characteristics to the observed speed time traces, which is 
consistent with the methodology adopted by Kuhler & 
Karstens (1978). Accordingly, they obtained the represen- 
tative urban driving speed time traces summarized in 
Table 3, for morning peak (MR), evening peak (EP) and off 
peak (OP) periods Tor each region. 

These speed time traces were converted into speed accel- 
eration probability matrices, where each matrix cell, of size 
5 km h ^ by 1 km h ’ s ^ contains the total number of one- 
second observations in the respective range from the rep- 
resentative driving cycle. Thus each matrix element rep- 
resents the total time during the representative driving 
cycle that the vehicle was at that speed and 
acceleration. 

Post et al (1985) extended the analysis of Kent & 
Mudford (1979) to 177 Australian light duty vehicles in 
use, and obtained fleet averaged emission rates as a func- 


tion of vehicle velocity and acceleration. Their results are 
presented at the same resolution as the speed acceleration 
probability matrices. Since cell averaged emission rates are 
independent of the velocity profile followed by the vehicle 
(Post et al 1981a, b), these can be used to estimate 
emissions for any driving pattern, assuming that the ve- 
hicles used by Post et al (1985) are representative of the 
typical Australian urban fleet. Hence the total emissions 
over a representative driving cycle can be expressed as 

» n i n 

in L 21 ‘i.i 

i 1 ) 1 

where [P] is the emission (g) of pollutant species P, e, is the 
emission rate (g s ’) of pollutant species P for the matrix el- 
ement defined by velocity i and acceleration j (Post et al 
1 985), tjj total time(s) vehicle spent at that velocity and ac- 
celeration during the driving cycle and the summation is 
over all possible speed acceleration cells. (P) is the total 
emission over the period of the driving cycle. Hence the 
characteristic emission factor (g km' ^) for that driving cycle 
can be represented as 

[fk - in/d, 

where d,^ is the distance covered during the driving cycle 
(see Table 3). 


Table 3 


Characteristics of representative driving cycles for each area and time period, where MP is morning peak, OP off 

peak and EP evening peak 


Area 

Dist. 

Aver. 

RMS 

Stops 

Idle 

Cruise 

Distance 

from 

Speed 

Accel. 

per 

Time 

Time 


CBD 


km. 


(%) 

(km) 


(km) 

(km h'*) 

(m s ‘) 

(km') 

(%) 

1 

MP 

2 

30.0 

0.89 

1.60 

20.6 

13.8 

11.9 

OP 


35.1 

0.86 

1.43 

15.6 

13.7 

11.9 

EP 


30.6 

0.87 

1.60 

18.4 

12.5 

11.9 

2 

MP 

5 

36.4 

0.80 

1.39 

17.9 

27.5 

14.5 

OP 


43.1 

0.82 

0.84 

9.6 

38.3 

14.2 

EP 


38.8 

0.85 

0.95 

17.9 

30.3 

16.8 

3 

9 


17.7 

MP 


40.6 

0.78 

0.79 

11.4 

30.8 

OP 


46.7 

0.70 

0.45 

5.3 

35.5 

17.8 

EP 


45.3 

0.71 

0.56 

8.2 

38.5 

17.7 

6 

11 


MP 


42.4 

0.74 

0.72 

13.3 

36.7 

19.4 

OP 


47.4 

0.76 

0.54 

11.3 

44.7 

20.3 

EP 


45.2 

0.76 

0.64 

14.4 

49.5 

20.3 

4 

MP 

13 

37.6 

0.77 

1.08 

14.3 

30.6 

19.4 

OP 


46.8 

0.80 

0.67 

10.1 

46.7 

19.4 

EP 


41.1 

0.76 

0.82 

18.3 

33.7 

19.4 

5 

MP 

19 

52.9 

0.69 

0.33 

3.4 

59.4 

18.4 

OP 


52.0 

0.70 

0.27 

3.6 

55.2 

18.3 

EP 


50.0 

0.78 

0.30 

4.6 

54.9 

19.8 


69 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Within Australia, exhaust emission rates for CO and 
NO^ for heavy duty diesel powered vehicles remain un- 
controlled and no locally validated data was readily avail- 
able. Emission rates based on US experience and assumed 
independent of vehicle speed are listed in Table 4 (Stern 
1976, USEPA 1977). These represent uncontrolled 
emissions averaged over a number of vehicles, operating 
under a variety of conditions, and are consistent with the 
heavy duty emission rales used by Jakeman et at (1984) for 
Australian conditions. Luria et at (1984) obtained similar 
values for buses and expressed the emission factors for 
N’O , HC and CO as a function of speed. They showed a 
marked decrease in CO and HC emissions with speed and 
an increase in NO^ emissions up to a speed of 40 km h In 
the absence of alternate emission factors these were used. 

Trucks within the Perth metropolitan area are mostly 
able to maintain easy cruise conditions and appear to avoid 
built up areas and peak conditions (Lyons et al 1987). Un- 
like automobiles, their driving cycle shows no dependence 
on location or time period. Consequently, as tne heavy 
duty diesel emission factors are only expressed as a func- 
tion of speed, the average speed from the Perth truck driv- 
ing cycle of 43.2 km h ' (Lyons et al 1 987) was assumed for 
all truck emissions, leading to the emission factors shown 
in Table 4. 

Table 4 

General emission factors (g km'*) for heavy duty diesel 
powered vehicles (after ^Stern 1976; *USEPA 1977) and 
those used in this study assuming an average speed of 
42.3 km h'* (after ^Luria et al 1984). 


Emission factor 

Pollutant 

g km ' 


(1. 2) 

(3) 

Particulates 

0.8 


CO 

17.8 

9.5 

HC 

2.9 

1.5 

NO, 

13.0 

10.2 

Aldehydes 

0.2 


Organic acids 

0.2 


so. 

1.7 


The total emission in any period and any area of the city 
can be expressed as 

m n 

E- L [nk„,VKT,„ 

m • 1 

where [P] ^ ^ and VKT ^ are the emission factor and total 
VKT, respectively, for that time period and area and the 
summation is over vehicle type. 

Results and Discussion 

Combining the characteristic driving patterns 
(Kenworthy et al 1983) and the fleet emissions (Post et al 
1985) led to the automobile emission factors shown in 
Table 5 for each of the representative areas. As these fac- 
tors are based on the same fleet data, the differences are di- 
rectly attributable to the style of driving in each of the 
areas. This emphasizes the contribution of variations in 
speed and acceleration patterns across a metropolitan area 
in determining the spatial variation of emissions. 


Table 5 


Emission factors g km'* for exhaust emissions for each 
time period and region based on speed acceleration 
matrix. 


Area 

1 

2 

3 

6 

4 

5 

NO, 

MP 

1.9 

1.8 

1.8 

1.7 

1.9 

1.7 

OP 

1.9 

1.9 

1.7 

1.8 

2.0 

1.7 

EP 

1.8 

1.8 

1.8 

1.9 

1.9 

1.8 

CO 

MP 

21.8 

18.4 

18.1 

16.9 

19.2 

14.8 

OP 

19.2 

17.4 

15.7 

15.9 

16.8 

15.2 

EP 

21.3 

18.5 

16.7 

16.9 

17.5 

16.0 

HC 

MP 

2.2 

1.9 

1.9 

1.8 

2.0 

1.8 

OP 

2.0 

1.8 

1.7 

1.8 

1.8 

1.7 

EP 

2.2 

1.9 

1.8 

1.9 

1.8 

1.7 


The corresponding automobile emission factors based 
solely on average speed in each of the regions (Table 3) are 
shown in. Table 6, With the exception of the NO^ emission 
factors, the average speed factors are lower, as would be 
expected, since the incorporation of acceleration leads to 
greater variability in the driving patterns and hence higher 
emissions. The NO^ emissions are higher because the aver- 
age speed equation implies a speed independent emission 
of 2.2 g km ‘ (Kent & Mudford 1979) compared to the idle 
emission of 0.039 g min ' of Post et al (1985). Their results 
also suggest that emissions of the order of 2.2 g km * are 
only observed under high acceleration which is not main- 
tained for any length ot time in representative urban driv- 
ing cycles (Lyons et al 1986). 

Table 6 


Emission factors (g km'*) for exhaust emissions for each 
time period and region based on average speed. 


Area 

1 

2 

3 

6 

4 

5 

NO, 

MP 

2.4 

2.5 

2.5 

2.5 

2.5 

2.6 

OP 

2.5 

2.5 

2.6 

2.6 

2.6 

2.6 

EP 

2.4 

2.5 

2.6 

2.6 

2.5 

2.6 

CO 

MP 

17.2 

14.2 

12.8 

12.3 

13.8 

9.9 

OP 

14.7 

12.1 

11.2 

11.0 

11.2 

10.1 

EP 

16.8 

13.4 

11.5 

11.5 

12.7 

10.5 

HC 

MP 

1.8 

1.6 

1.4 

1.4 

1.5 

1.2 

OP 

1.6 

1.4 

1.3 

1.3 

1.3 

1.2 

EP 

1.8 

1.5 

1.3 

1.3 

1.4 

1.2 


70 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Within Perth, areas 1 and 5 illustrate the greatest differ- 
ences in activity intensity ranging from the congested CBD, 
with its greater reliance on public transport, to the private 
vehicle dominated outer suDurbs. Emission factors, based 
on the speed/acceleration distribution, show a decrease in 
emission factor between the CBD and the outer suburbs for 
NO^ corresponding to decreased accelerations character- 
ised by hign average speeds and maintained cruise con- 
ditions. Alternatively, emission factors based solely on av- 
erage speed illustrate an increase as you move away from 
the congested CBD. Thus, a simple average speed model 
suggests higher emissions away from the congested CBD 
by not accounting for the marked acceleration changes in- 
duced by the congested stop start driving of the CBD. 

The Perth metropolitan region was divided into grid 
squares of I km by 1 km and estimated daily VKT for each 
of these was obtained from traffic count information col- 
lected by the Main Roads Department (MRD 1986). Auto- 
matic traffic counts, of 1 -3 days duration, are carried out on 
all major roads in the region, as well as points on these at 
which a change in volume might be expected. They are ex- 
pressed as annual average weekday traffic flow and rep- 
resent the 24 hour traffic volume passing through a site on 
a typical weekday (MRD 1986). 

These individual grid values were summed tqprovide an 
overall measure of the recorded total daily VKT for Perth. 
Any shortfall between this figure and the estimated total 
VK*r, listed in Table 7, can oe attributed to subarterial 
roads. This was allocated across the region on the basis of 
the recorded traffic volumes. 


Table 7 


Estimated total VKT (Vehicle Kilometres Travelled) for 
Perth for 1985. Note weekend VKT is estimated at 1.5 
average weekday VKT (after ABS 1985). 


Vehicle Class 

Equivalent 

Total Annual average daily 

VKT (lO'^ km) VKT 

(10^ km) 

Automobiles 

6.996 

2.064 

Utilities/Panel vans 

1.168 

0.345 

Total Motor vehicles 

8.164 

2.409 

Trucks 

0.445 

0.131 

Motor cycles 

0.138 

0.041 

Total 

8.747 

2.581 


The total truck VKT, given in Table 7, was allocated to 
high truck usage routes in the metropolitan area (Lyons et 
al 1987) on the basis of the total gria VKT and subtracted 
from the individual grid totals. As the truck driving cycle is 
independent of peak periods, the truck VKT was divided 
by 24 to represent an average hourly truck VKT. 


24 hour VKT weightings for Perth are 16.5% morning 
peak (0700-0900), 18.5% evening peak (1600-1800) and 
65% for all off-peak times (Kenworthy et al 1983). Conse- 
quently, the daily VKT for each grid square was corrected 
by these factors and divided bv the length of the period to 
provide an hourly estimate of non -truck VKT. 

The truck and non-truck VKT were then multiplied by 
the appropriate emission factors (Tables 4, 5), to provide an 
estimate of the total vehicle exhaust emission across the 
metropolitan area. Additional evaporative emissions are 
accounted for from the distribution of registered vehicles 
and added to the total for HC. Figure 1 illustrates the 
spatial variation of the calculated morning peak and off 
peak NO^ emissions. The major arterial roads are clearly 
visible as well as the increased emission during the morn- 
ing peak period. Given the small variation in NO^ emission 
factors across the region, the major spatial variations are 
the direct result of variations in VKT. Similar maps were 
obtained for the other pollutant species. 

Emission totals presented in Figure 1 are not directly 
verifiable as they are based on average traffic conditions 
across the metropolitan area, which are not necessarily ob- 
served on any one day. However they do indicate the 
spatial variation in source strength anc! provide an indi- 
cation of the relative magnitude of pollutant sources in dif- 
ferent regions. An alternative statistic can be obtained from 
Table 5 by computing the predicted CO/NO^ ratio on the 
basis of both time period and location (Table 8). 


Table 8 


Variation of CO/NO ratio across the Perth airshed re- 
sulting from tempor^ and spatial variation in driving 
patterns, where MP is morning peak, EP evening peak 
and OP off peak. 


CO/NO^ ratio 

Region mp pp OP 

0700-0900 1600-1800 


Central Core 

11.5 

11.8 

10.1 

Inner suburbs 

10.2 

10.3 

9.2 

Middle western 
suburbs 

10.1 

9.3 

9.2 

Middle south, outer 
north and eastern 
suburbs 

9.9 

8.9 * 

8.8 

Outer south east 
and north east 
suburbs 

10.1 

9.2 

8.4 

Northern state 
housing suburbs 

8.7 

8.9 

8.9 


A69349-2 


71 


Journal of the Royal Society of Western Australia 72 (3), 1990 


The greater corjgestion and higher accelerations as you 
approach the CBD leads to an increase in the CO/NO^ 
ratio of pollutants emitted from the exhaust pipe. As both 
smog-chamber and computed results suggest that added 
CO accelerates the depletion of NO and the generation of 
NO 2 as well as enhanced generation of O 3 tnrough NO 2 
photolysis (Demerjian et at 1974, Drake et al 1979), the 


change in driving patterns brought about by increased con- 
gestion enhances smog formation, through increased CO 
generation per kilometre of travel. Given the increased 
concentration of vehicles usin^ the CBD this becomes sig- 
nificant. If evaporative emissions are also included, the 
greater number of vehicles in the CBD would lead to a cor- 
responding increase in HC emissions. 


Figure 1 Predicted emission of NO^ (g hr *) across Perth for the morning peak (MP) and off peak (OP) periods. 

72 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Conclusions 

The integration of driving characteristics and vehicle 
emissions based on speed and acceleration illustrates a 
marked variation in emission factors from the CBD to the 
outer suburbs. In particular, the greater congestion and 
corresponding variations in acceleration within the CBD, 
increases the production of pollutants and the potential for 
photochemical smog through enhanced CO production. 

Thi* di'Vflopmenl of the Perth air«»hed model has been 
tunded under the Australian Research Grants Scheme, whereas the driving 
cvcic data was colletled under iundtng from the State Energy Commission tn 
Western Australia and the National Energy Research, Development and Dem- 
onstration Programme, which is administered by the Commonwealth Depart- 
ment of Resources and Energy. All of this assistance is gratefully 
acknowledged. 


References 

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journal of the Royal Society of Western Australia 72 (3), 1990 


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Lyons TJ. Kenworthy J R. Austin P I ft Newman P W G 1986 The development 
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74 


Journal of the Royal Society of Western Australia 72 (3), 1990, 75-92 


Stratification and disconformities in yellow sands 
of the Bassendean and Spearwood DuneS/ 
Swan Coastal Plain, South-western Australia 


D K Glassford' & V Semeniuk^ 


*33 Rockett Way, Bull Creek, WA 6155 
^21 Glenmere Road, Warwick, WA 6024 


Manuscript receivctl September 1988: acccptcit }aiiuar\f 1989 


Abstract 

Yellow sand of the Pleistocene Bassendean and Spearwood dunes of the Swan Coastal Plain of SW 
Australia contains sedimentary stratification at depth (>3-5m). Yellow sand is divided into units of high 
and low angled inclined strata, horizontal strata, and massive sand. Sequences of sand typically contain 
up to five major disconformities. Dip direction resultants of inclined strata at individual study sites indi- 
cate that Pleistocene wind directions were dominantly from the eastern sector, sub-dominantly from the 
NW, and to a minor extent from the W and SW. Dip direction mean vector resultant of all inclined strata 
is 210° indicating that the sands were transported mainly from the NE. These data preclude, as major 
processes, origin of the yellow sand by either iu situ decalcification of coastal limestones or by coastal- 
marine derivation as carbonate-free quartz sand. Cross-strata and horizontal strata were emplaced by 
the migration of desert aeolian dune fields (desert ergs) during at least six glacial age arid phases, mostly 
during the middle Pleistocene. During the intervening wetter interglacial periods yellow sands were ex- 
tensively bioturbated to depths of 3-5m, thereby degrading the dunes and producing massive yellow 
sand under the major disconformities. 


Introdoction 

The Swan Coastal Plain of the Perth Basin, South- 
western Australia has an extensive cover of mainly 
Pleistocene siliciclastic sand (McArthur & Bettenay 196(5, 
Playford etal 1975, 1976; Wilde & Low 1978, 1980; Fig. 1). 
This cover includes Bassendean Sand, yellow sand 
overlying Tamala Limestone, and some of their altered 
equivalents such as white quartz sand, brown quartz sand 
and brown sandstone. These sand formations traditionally 
have been interpreted as coastal -marine derived cal- 
careous deposits which have been decalcified in situ by 
leaching processes to a residue of yellow quartz sand 
(Prider 1948, McArthur & Bettenay 1960, Lowry 1977, 
Wyrwoll & King 1984, amongst others). 

Crucial evidence of long standing for decalcificalion (e^ 
Prider 1948) is, that near the coast where yellow sand 
overlies limestone, from which traditionally it is concluded 
the sand was leached, the yellow sand has a massive struc- 
ture {eg Spearwood Dunes). Inland where yellow sand 
does not overlie limestone it generally also has a similar 
massive structure (c;? Bassendean Sanci, yellow sand of the 
Yoganup Formation). Thus massive structure (absence of 
lamination/ bedding) has been cited as key evidence for an 
in situ decalcification origin. However, documentation of 
these sand formations in terms of their genetically import- 
ant sedimentary features (c^ stratigraphy, geometry, struc- 
ture, fabric, texture and composition) is negligible. 


This paper provides the first detailed treatment of pri- 
mary sedimentaiy structures in the yellow sands of the 
Bassendean and Spearwood dunes within the central sec- 
tor of the Swan Coastal Plain (Fig. 1 ). The paper deals only 
with Bassendean Sand and the quartz sand overlying the 
Tamala Limestone referred to the Karrakatta and Cottesloe 
soil associations (McArthur & Bettenay I960), and specifi- 
cally excludes the Cooloongup Sancf with its local grey 
coloration and occasional shell content (Passmore 1970), 
ellow sand of the Yoganup Formation (Low 1971), Eaton 
and (Semeniuk 1983X the complex quartz sand deposits 
of the hinterland of Geographe Bay (Baxter 1977), and 
possible minor non-aeolian facies of the yellow sands {eg 
Wyrwoll & King 1984). It is also stressed that this study 
mainly concentrates on primary sedimentary features of 
the yellow sands anci not on their - pedogenic or 
geohydrologic alteration products such as humic quartz 
sand, white quartz sand and ferruginized sand. These vari- 
ous secondary overprints are briefly described as a back- 
ground to understanding the destruction of primary sedi- 
mentary structures in yellow sands. 

Previous studies 

The major geological attributes of Perth Basin yellow 
sand have not been documented in systematic detail. 
These attributes should include genetically critical sedi- 
mentary features such as geomorphic expression, bound- 
ary types, stratigraphic associations and relationships, ge- 


75 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Figure 1 Location and regional setting of study sites. A Location of study area in Western Australia. B Location of study 
area in the Perth Basin. C Regional geomorphic units of the Swan Coastal Plain, the landward portion of the central Perth 
Basin, and their relationship to insets of study site settings (after McArthur and Bettenay I960). D, E, F & G Location and 
setting of study sites (geomorphic unit boundaries after Gozzard 1983, 1986; Jordan 1986). Note the boundary between 
the Bassendean and Spearwood Dune sands as mapped by Gozzard (1983, 1986) and Jordan (1986) is 1.5 to 4km further 
east than it is as mapped by McArthur & Bettenay (1960). 


76 


Journal of the Royal Society of Western Australia 72 (3), 1990 


ometry and dimensions, internal structure (types, dip 
angles, dip directions etc), fabric, texture (grain size, 
sorting, percentage fines, roundness, etc) and composition 
(grain types, grain coatings, internal features of grains, 
mineralogy of grains ffc) {eg see Folk 1974, Pettijohn et al 
1987, Lincfholm 1987). Previous investigations into yellow 
sand have been directed towards agriculture and pedology 
(McArthur & Bettenay i960), environmental and land use 
planning (Dept of Conserv & Envir 1980), hydrology and 
groundwater supply (Allen 1981), engineerir^ (Klenowski 
1976), heavy mineral deposits (Baxter 197^, geological 
mapping (Wilde & Low 1978, 1980; Gozzard 1983, 1986; 
Jordan 1986); and lithostratigraphic sub-division and defi- 
nition (Low 1971, Playford & Low 1972). These studies 
provide information on various aspects of yellow sand, but 
they are not directly relevant to unravelling its origin. De- 
spite this, many of these studies form the basis for the tra- 
ditional views of coastal-marine derivation and in situ de- 
calcification for the origin of yellow sand (Lowry 1977). 
Two published studies have dealt specifically with the gen- 
esis of Perth Basin yellow sand (G)assford& Killigrew’ 1976 
and Wyrwoll & King 1984). These studies, however, fo- 
cused mostly on the textures of yellow sand. 

Although stratification is an important feature for inter- 
preting the origin of sand (Potter & Pettijohn 1977, 
Lindholm 1 987), it has not been the subject of any previous 
work on Perth Basin yellow sand. Generally, yellow sands 
are regarded to be structureless or massive (eg Prider 1948, 
Wyrwol! & King 1984). Theonly published mention, toour 
knowledge, of stratification in yellow sand is the reference 
by Baxter (1977) to "delicate cross-bedding" in Bassendean 
Sand in the Busselton area. 


Methods 

Stratification and disconformities in yellow sand se- 
quences were studied in 15 ouarry exposures in the Perth 
region of the Swan Coastal Plain (Fig. 1). These quarries 
represent all sand quarries that to our knowledge were 
being excavated during this study. Stratification was best 
studied in winter when the sand is moist. In summer, the 
sand is dry and commonly slumps during and following 
excavation. This slumping covers the deeper sequences of 
yellow sand, thereby typically concealing stratification. 
Four of the quarries are located in the middle to eastern 
parts of the Spearwood Dunes; eleven of the quarries are in 
the Bassendean Dunes. Structures within the sand were 
documented using the terminology of McKee & Weir 
(1953) and Lindholm (1987). Stratification and 
disconformities were mapped in the field onto panoramic 
photographs of quarry W'alls. 

The true dip angle and dip direction of cross-layering 
was determined by measurements on partially excavated 
individual surfaces of the sedimentary layers or laminae of 
a given cross-layered set which were traceable in three di- 
mensions. Usually 5-10 separate laminae were measured 
in this manner at each sampling locality. Depending on the 
amount of exposure, 2-5 sites typically xvere measured in 
each quarry. Dip angle and dip direction (magnetic) read- 
ings were taken according to tne number and thickness of 
large scale cross-layered sets. Most readings w'ere at c 0.5- 
1 .5m vertical intervals for a set. For example, for a 3m thick 
set, three readings were taken at approximately 0.5m, 1 .5m 
and 2.5m above the base of the set. In the case of a 5m thick 
set five readings were taken at approximately, 0.5m, 1.5m, 
2.5m, 3.5m and 4.5m above the base of the set. The con- 
straints of availability and wall condition of quarries has 
limited the data base of this paper to 228 dip angle and di- 
rection measurements of inclined strata from 12-15 lo- 


calities. Additional measurements should be collected as 
existing quarries are excavated further and when new 
quarries are opened. 

Sketches and photographs were used to record second- 
ary overprints. Sediment was carefully sampled in situ by 
a 5 cm corer and retrieved to the laboratory for impreg- 
nation and slicing. Oriented thin sections were prepared 
from the impregnated in situ blocks for petrographic study. 
Selected laminae and groups of laminae also were sampled 
and sieved at half phi intervals for granulometric analysis. 
Representive samples and sub-samples were x-rayed with 
Co K-alpha radiation and diffractograms were interpreted 
using Brindley & Brown (1980). 

Nomenclatare 

The Sahara Desert term erg is used in this study. Orig- 
inally erg referred to a vast region in the Sahara Desert cov- 
ered by deep aeolian sand (Gary et al 1972). Implicit in this 
original meaning were a mid-latitude location, a desert set- 
ting, and a continental, as distinct from coastal, character 
and derivation for the sand. Subsequent workers, how- 
ever, expanded the original meaning of the term to en- 
compass large scale coastal and non-desert aeolian sand 
bodies, or sand seas (e^ Blakey rf al 1988; Marzolf 1988). It 
is therefore important to define the sense in which erg is 
used. In this study erg refers to a vast, large scale or re- 
gional scale tract of continental desert-aeolian sand in the 
form of sheets and dunes. For added emphasis and clarity 
the term is used in conjunction with desert, ie desert erg. 
Other types of aeolian sand seas can then be categorized, 
for example, as coastal erg or humid erg. 

The term desert is used in this paper in the sense of low 
to middle latitude terrains with no vegetation cover or with 
a vegetation cover which is too sparse to prevent wide- 
spread aeolian transport of sand. Controls such as effective 
rainfall, windiness, sand supply etc may variously contrib- 
ute to producing a desert terrain. For a discussion of the 
main factors which can produce a desert-aeolian terrain 
see Ash & Wasson (1983) and Marzolf (1988). 

Geological setting 

The study area is within the Swan Coastal Plain, a 
coastal lowland of the Perth Basin with a mainly relict 
Pleistocene surface (Playford et al 1976, Wilde & Low 
1978, 1980). Within this setting there is a Pleistocene 
lithostratigraphic unit of yellow sand (Prider 1948, 
Glassford 1980) relevant to this study w'hich usually has 
been assigned to more than one formation (Fig. 1): 

• vellow quartz sand portion of Bassendean Sand (- 
bassendean Dunes of McArthur & Bettenay, 1960) 

• yellow quartz sand assigned to the Tamala Limestone 
(within the Spearwood Dunes of McArthur & 
Bettenay, 1960). 

To date, however, the bulk of the yellow quartz sand 
overlying the Tamala Limestone within the Spearwood 
Dunes has not been formally recognized as a separate for- 
mation, except in local areas such as Rockingham 
(Cooloongup Sand; Passmore 1970) and Australind (Eaton 
Sand; Semeniuk 1983). Lithologically similar yellow sands 
(Prider 1948, Glassford 1980) which are located east of 
Perth on the eastern margin of the Pinjarra Plain and in the 
foothills of the Darling Scarp (Low & Lake 1970, Low et al 
1970, Wilde & Low 1978, 1980) have been assigned to the 
Yoganup Formation (Low 1971). For the sake of simplicity 
the Yoganup Formation yellow sands in this complex 
geomorphic setting are excluded from the present study. 


77 


Journal of the Royal Society of Western Australia 72 (3), 1990 


The age of the yellow sands is interpreted to be mainly 
middle Pleistocene (Playford et al 1975). It forms much of 
the land surface of the coastal plain to landward of the 
Holocene coastal dune belt and the Pleistocene limestone 
ridges. Where the yellow sand underlies the coastal 
limestones it may range to Pliocene in age (Logan et al 
1970, Glassford 1980). 

The terrain of yellow sand on the coastal plain is the 
western fringe of a vast, diachronous cover of sand dunes 
and sand sheets which extend westwards from the central 
Australian Desert (Killigrew & Glassford 1976, Glassford 
1980, 1987, Beard 1984). Thus yellow sand occurs exten- 
sively on the Yilgam Block and forms an extensive and 
thick lithosome that underlies and overlies coastal 
limestones and underlies landward parts of the coastal 
plain (Semeniuk & Glassford 1988). 

On the coastal plain near the present coast, there is a 
shore-parallel belt of Pleistocene coastal limestone ridges 
(Tamafa Limestone). These ridges, with variable cover of 
yellow sand, form shore outcrops, or may be buried by 
Holocene littoral and coastal-dune deposits. In cross sec- 
tion the coastal limestone complex forms a large lens 
mainly on, but also within, the western margin of the 
aeolian sand sheet described above, a relationship that is 
evident for much of the west coastal region of Western 
Australia from Shark Bay to Perth, a distance of over I 200 
km (Logan et al 1970, McWhae in Quilty 1974, Glassford 
1980, Allen 1981, Semeniuk & Glassford 1988). The east- 
ern contact of the limestone-ridge-belt with yellow quartz 
sand of the hinterland is complicated; ie it may be sharp, or 
lithologically gradational, marked by east-west inter- 
fingering, or marked by zones of scattered limestone lenses 
in yellow sand (Semeniuk & Glassford 1988). 

The lithofacies referred to herein as yellow sand, 
although typically yellow, also includes sands varying 
from red to brown to locally white. Grain sizes range from 
bimodal to poorly unimodal to unimodal, and the sand is 
typically fine skewed, well to poorly sorted and medium 
sized. Framework grains are predominantly quartz, with 
moderate to minor microcline and minor heavy minerals. 
The grains have a coating of silt-clay sized kaolin, goelhite 
(yellow) and/or haematite (red) and quartz. These latter 
rninerals also occur in the less than O.Ovmm fraction of the 
sediment (Glassford 1980). 


Description and interpretation of 
stratification in yellow sand 

Contour data from 1 :25 000 topographic sheets and field 
observations of surface morphology indicate that sites 1, 2, 
3, 4 and 7 of this study are within large scale sand-sheet 
ramparts which drape the landward side of the coastal- 
limestone-ridge belt; sites 5 & 6 are in sinuous and para- 
bolic landforms; and sites 8 to 15 are within an east- west 
oriented linear draa with stellate landforms (Table 1; Fig. 

1). The term Jraa refers to large scale dunes or megadunes 
and compound or complex types of composite dunes 
(Wilson 1972, Leeder 1982, Lancaster 1988). 

On the basis of presence/absence and inclination of 
large scale (> Im thick) sets of stratification, yellow sand is 
divisible into: 

1) units with inclined strata ie cross-strata (high and low 
angled); 

2) units with horizontal strata; and 

3) units with massive structure. 


These features are described below. Small scale (<0.3m 
thick) sets of cross-strata were not observed at any of the 
sites. The thinnest recognizable strata or laminae that com- 
prise sets of cross-strata and horizontal strata in yellow 
sand are mostly evident due to differences in size of frame- 
work sand grains and, to a lesser extent, to varying 
amounts of yellow to brown silt-clay sized matrix fill of 
kaolin and goethite and variations in framework-grain 
coatings of kaolin and goethite. 

Inclined strata 

Description 

l^rge scale sets of inclined strata (commonly referred to 
as cross-strata) occur extensively in 13 of the quarries 
(Table 1). Sets of cross-strata typically are up to 5- 10m 
thick, and generally, only occur at depths of more than 
3-5m below the present landsurface. Cross-stratification 
consists dominantly of tabular-shaped sets of planar cross- 
strata with local minor occurrences of wedge-shaped and 
hummocky-shaped sets of planar and cur\'ed cross-strata 
(Figs 2, 3 & 4). Tabular-shaped sets of planar cross-strata 
have been traced continuously along recently exposed 
quarry faces for distances of 10 to 100 m. Generally ex- 
posures of cross-stratification are limited by an upper zone 
of bioturbation, or by lateral slumps of quarry walls, or by 
quarry floors. 


Table 1 


Sand quarries near Perth with large scale 
cross-stratification and major disconformities. 


Quarries examined 
and their site 
numbers' 

Large scale 
cross-stratification- 

Major 

disconformities' 

1 Wangara North 

present 

2 present 

2 Wangara 

present 

3 present 

3 Landsdale West 

- 

2 present 

4 l.andsdaie East 

- 

1 present 

5 Bcihus 

present 

- 

b Henley Brtxik 

present 

1 present 

7 Mirrabt)oka 

present 

5 present 

H landakot West 

present 

- 

9 Jandakot East 

present 

- 

10 jandakot North 1 

present 

- 

1 ] jandakot North 2 

present 

- 

12 Canning Vale 

present 

1 present 

13 Banjup West 

present 

1 present 

14 Banjup East 1 

present 

1 present 

15 Banjup East 2 

present 

1 present 


' See Fig. 1 for location of sites. 

- Large-scale is defined as greater than l.Om thick. 

' Number of major disconformities in the yellow sand sequences. 


78 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Figure 2 Range of stratification features at a single typical locality, Ban jup West. See Fig. I for location. A Panoramic dia- 
gram of stratification and location of insets. B Alarge scale, tabular set of planar horizontal strata overlain by a large scale, 
wedge-shaped set of planar cross-strata (inclined strata). C A large scale set of concave-upwards, trough cross-strata. 
Note the rivulets of flowing sand which are building avalanche cones of sand. The continued growth of avalanche cones 
of sand will eventually conceal the stratification. D Thinnest recognizable strata in a large-scale set of low angle, planar 
cross-strata produced by differences in grain size of framework sand grains. The coarser layers (a) resemble ripple-form 
strata of Hunter (1977). The finer layers (b) resemble grainfall strata of Hunter (1977). Coin is 21mm in diameter, t Layer- 
ing in a large-scale set of planar cross-strata produced by differences in texture, composition and colour. Thin prominent 
layers have framework quartz-sand grains supported in a silt-clay matrix of yellowish brown goethite, kaolin and quartz. 
Thick layers lack the silt-clay matrix. Coin is 28mm in diameter. F Disconformity (a) between two units of yellow sand. 
The discontinuity between the units is produced by: geometry of interface; changes in stratification details away from the 
contact; and structural, textural, compositional and colour differences between the two units on either side of the 
interface. The massive zone below the disconformity is a palaeosol (b) which indicates the disconformity is a regional 
bounding surface (Talbot 1985). Note also the common inaistinct appearance of stratification. Several metres of surfidal 
sand has teen removed from this section by excavating machinery. Spade for scale is 1 m in length. G Closer view of dis- 
conformity surface, sloping from upper left to lower right and with underlying, mostly massive palaeosol with rare or- 
ganic material and burrow -structures (a). Note rivulets of flowing sand on the leit hand side. Coin is 24 mm in diameter. 


79 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Site 1 (View looking east] 

white sand major disconformity 


Site 2 (View looking north} 

major disconformities 


Site 2 (View looking northeast) 

major disconformities timestone lens 


Site 5 (View looking northeast) 

^modified land surface 


C o •• *• -• 

V-H 


4- 6fn •••o‘'oc. 


Site 6 (View looking southwest) 


Site 14 (View looking northeast) 

major disconformity 


* 

« - * _ • o'! 4 

o" - - .• •• • 

2-3m**o*«"*«*«V***V" I »• 


•V^Vv-H I ‘*o“; 


Site 7 (View looking southwest) 


major 

disconformities 


modified 
land surface 


Site 8 (.View looking northeast) 


Site 8 looking northwest) 

modified land surface 


• •po 


Site 9 (View looking northwest) 


Site 10 (View looking northwest) 


r V 

- - *• i." V*H L 1m o 

Site 15 (View looking west) 

modified land surface 

-I 

• ••• ^1 ~i^ii • 

* • • • vu' 

I V«H . . . . . _ 

•• S •• o •• • •• • •• •*“ 2m •• i •• I I •• J 


•• ir-o*r 

* • * 1-9-9 ftm 


NB: 


Explanation 

Stratified yellow quartz sand showing 
most prominent stratification. 

Massive yellow sand with thin zones ot 
white and brown sand. 

Slumped sand, formed after excavation 

Disconformity 

All land surfaces have been modified by 
earth-moving machinery 


Figure 3 Panoramic diagrams of stratification attitudes and relationships within sequences of yellow sand, Swan Coastal 
Plain, southwestern Australia. See Fig. 1 for locations. 


80 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Figure 4 Primary stratification and secondary overprint fetures in yellow sand. See Fig. 1 for locations. A Four units (1, 
2 3 4 of yellow sand bounded by three disconformjties (1, 11, III), Mirrabooka quarry. Note the common indistinct nature 
of the stratification. Unit 1 is mostly massive. Unit 3 has large scale, high angle planar and langental cross-strata which 
dip towards the west (towards RHS). Unit 3 has large scale, high and Tow angle planar cross-strata which dir towards 
the east (towards LHS). Unit 4 has been truncated by earth-moving machinery. Spade for scale is 1 m in length See I able 
2 & Fig. 7 B Set of large scale, low angle, planar cross-strata dipping towards the southwest (towards LHS),-JandaKOt 
North /. Note firstly, cross-stratification at depth is obscured by cone- shaped slumps of sand along the base of the cross- 
stratified sand escarpment. Secondly presence of an overlying soil of white and black sand which has been disrupted and 
partly removed by earlhmoving macninery. Set is 7-8 m thick. C Set of large scale, broadly concav'e-upwards, trough 
c^ross-strata, Jandakot West. Note 28 mm diameter coin in lower left hand corner, below a broad trough-shaped bounding 
surface (a). Stratification is obscured by slumped sand on the lower right hand side. D Large-scale set of low angle and 
horizontal strata which resemble grainfall ana plane bed strata of Hunter (1977). Strata underlie an mterdune area, ban- 
ning Vale. Coin 28mm in diameter. E Rare cut-and-fill structure, Banjup West. Lower set of horizontal strata has been 
truncated bv erosion (? surface wash) and then overlain by an upper westward dipping O' large-scale high angle, 
tangental to planar cross-strata. F Burrow structure (a) in horizontallv stratified sand which has negligible goethite and 
kaolin silt-clav, Jandakot North. Layers resemble grainfall and plane ped strata of Hunter (1977). Coin is 28mm m diam- 
eter G Termi’tarium structured yellow sand, upper few metres of unit 4, Mirrabooka. In contrast to F above the sand is 
relatively rich in goethite and kaolin silt-day (see Table 2). H Large-scale set of low angle, planar cross-strata (lower one 
third) overlain by a large-scale set of horizontal strata (upper two thirds) which underlie an mterdune and are part y 
ferruginized to form brown sandstone {coffee rock). 


81 


Journal of the Royal Society of Western Australia 72 (3), 1990 


TRUE DIP ANGLE OF STRATA (®) 


Figure 5 Frequency distribution of true dip angles for high angle (equal or greater than 20“) and low angle (1.6-19“) cross 
strata and horizontal strata (0-1.5“) from yellow sands ofthe Perth area. Swan Coastal Plain, southwestern Australia. 


Dip angles of cross-strata have a bimodal frequency. 
High angle (equal to or greater than 20°) cross-strata coth- 
rise c 5 1 % of measurements and form a mode between 
5-30° (Fig. 5). The highest dip angle recorded for cross- 
strata in yellow sand is 35°. Low angle (1.6-19°) cross- 
strata comprise 49% of measurements and form a mode 
between 5-10°, and the mode is skewed towards 10-15° 
(Fig. 5). The proportion of high angle strata is probably 
lower than these figures indicate because of a bias in the lo- 
cation of quarries towards hill tops rather than plinths and 
interdune flats. 


The frequency of occurrence of dip directions (azimuths) 
of cross-strata at individual sites may be unimodal, 
bimodal or polymodal (Fig. 6). Individual disconformity- 
bounded sets of cross-strata at the same locality may have 
variable dip directions (Table 2; Fig. 7). At six sites cross- 
strata have mean resultant dip direction towards the Wand 
SW. At three sites cross-strata have mean resultant direc- 
tion towards the E and SE. At two sites cross-strata have 
mean resultant dip direction towards the NE. At one site 
the resultant dip direction changes between the various 
disconformity bounded units of yellow sand (Fig. 6). Dip 

82 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Table 2 


Description of lithology for the sequence of yellow sands at Mirrabooka quarry. See Fig. 1 for location. Grain size 

terminology after Folk (1974). 


DEPTH (m) 

DESCRIPTION 

LITHOFACIES 

0 to 4.0* 

Quartz sand; yellow, massive, sand-framework supported, unimodal, near symmetrical to fine skewed (range 4 0.0 to 
+ 0.12), well sorted to moderately well-sorted (range 0.47 to 0.61 phi), medium (range 1.21 to 1.63 phi) quartz sand with 
0.9% fines** (range 0.60 to 1.185(>); framework quartz-sand grains of yellow sand have a surface coating of goethite (yellow) 
pigmented kaolin plus silt-clay sized quartz. 

Unit 6 

DISCONFORMITY (V)"" 

4 to 9 

Quartz sand; white in upper 0 to 0.3m then yellow io9m, massive, sand framework supported, unimodal, near symmetrical 
(range + 0.02 to -0.05), moderately well -sorted (range 0.58 phi to 0.60 phi), medium (range 1.56 to 1.63 phi) quartz sand with 
1.18% fines (range 0.97 to 1.35%); framework quartz-sand grains of yellow sand have a surface coating of goethite (yellow) 
pigmented kaolin plus silt-clay sized quart/; the white sand does hot have a yellow coaling on grains. 

Unit 5 


DISCONFORMITY (IV) 


9 to 14 

Quartz sand; in places upper 0 to 0.3m white then yellow and yellowish red with white mottles to 14m; in places upper 0 
to 0.5-1. Om is termitarium structured with a tortuous network of vermiform voids or loose sand fill and labyrinthoia walls 
of coherent sand and silt-clayey sand; from 9 10 to I2.5m conspicuously cross stratified with large scale high angle strata 
dipping towards the southeast; from 12.5 to 14m conspicuously cross-stratified with large scalelow angle strata dipping 
towaras the southwest; sand -framework supported, unimodal to poorly unimodal, fine skewed to near svmmetrical (range 
* 0.15 lo -0.05), moderately well-sorted to moderately sorted (range 0.54 to 0,72 phi), medium (1.33 to 1.66 phi) uuarlzsand 
with 1.55% fines (range 0,88 to 2.08%); in places ihm beds of coarse sand; framework quartz-sand grains of yellow to red 
sand have a surface coating of goethite, haematite, kaolin and silt-clav sized quartz; white sand does not have coating on 
grain surfaces, 

Unit 4 

DISCONFORMITY (Ml) 

14 lo 17.5 

Quartz sand; brownish yellow to reddish yellow to brown with white mottk*s; conspicuously cn>ss-stratified; from 14 to 

17,5m large scale, high and low angle strata dip towards the nctrthcast and east; in places from 16 to 17.5m large scale, low 
angle cross-strata dip towards SSE; sand- framework supported, unimodal, near symmetrical (range + 0.03 lo ■» 0,06), moder- 
atiNV well-w>rted (range 0.52 to 0.60 phi), fine to medium (range 1.69 to 2.03 phi) quartz sand with 2.24% fines (range 1.84 
lo 2.74%); framework quartz. -sand grains of yellow to browm sand have a surface coating of goethite and kaolin plus silt-clay 
sized quartz; white sand mottles have grains which do not have surface coatings 

Unit 3 


DISCONFORMITY (II) 


17.5 to 20.5 

Quartz sand; pale yellow to reddish yellow; generally massive, in places faintly cross-stratified with high angle strata dipping 
towards the W & WNW; sand-framework supportecl, unimodal, near symmetrical to strongly fine-skewed (range + 0.(J8 to 
♦ 0.61), moderately well-sorted (range 0.64 to 0.69 phi), medium (range 1 ,41 to 1.7 phi) quartz sand with 2.85% fines (range 

2.53 to 3 13%); framework quartz-sand grains of yellow sand have a surface coating of goethite, haematite, kaolin and silt- 
day sized quartz, 

Unit 2 

DISCONFORMITY (1) 

20.5 to 26-t 

Quartz sand; yellow to red, w’hite in the virinity of the ground w-ater table (c 24 26m); generally massive, in places faintly 
cross-stratified with large scale, high angle strata dipping towards the NW; sand-framework supported, unimodal to poorly 
unimodal. near symmetrical lo slronglv fine skewed (range + 0.06 to 0.37), moderately well sorted lo moderately sorted 
(range 0.61 to 0,9? phi), coarse lo medium (range 0.97 to 1 .36 phi) quartz sand with 3.155fi fines (range 1 12 to 6.57%); frame- 
work quart/ -sand grains of vellow to red sand have a surface coaling of goethite (yellow) 6r haematite (red) pigmented kaolin 
plus silt-clay sized quartz; white sand in vicinity of groundwater table has grains which vio not have a surface coating; 
groundwater tabic c 0.5m below base of quarrv. 

Unit 1 


• N.nural surface ha*. iH-en removed. 

l-ines equal weight percentage of gram sj/e less than 0.09mm. Generally fines of yellow to red sand are composed of c50% kaolin, goethite and/or haematite 
and c 50^ quart/ and heavy minerals. Fines of white sand are composed of quart/ and heavy minerals. Note that there is a uniformly consistent decrease 
in the amount of fines from unit 1 at depth to unit h near the surface, l-urthermore modorn heach-berm sands average 0,09% fines (range 0-0.48%) and 
Holocene coastal dunes average 0.15% tines (range 0-0.62%), see details in Glassford (1980). 

••• Disconformities recognised by occurrence of palaeosols, undulating discontinuity surfaces, changes in structure massive to cross-stratified) and changes 
in fabric, texture, composition and colour. 


83 


journal of the Royal Society of Western Australia 72 (3), 1990 


Figure 6 Rose diagrams of dip directions of cross-strata for individual sites in the Perth area, Swan Coastal Plain, 
southwestern Australia. See Fig. 1 for locations. Map boundaries are after Wilde and Low (1978, 1980). 


84 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Figure 7 Vertical section of six disconformity-bounded 
units of yellow sand and the dip angles and dip directions 
of cross-strata for the respective lithoslratigraphic units of 
yellow sand. Note that the yellow sands are massive near 
the surface stratified at depth and then massive near the 
groundwater table. 


directions may vary markedly between and within units of 
yellow sand at the one site. For instance at Mirrabooka 
(Fig. 1) the lower strata of unit 4 dip towards 240* whereas 
middle to upper strata dip towards 160® (Table 2; Figs 6 & 

7) . 

The dip directions of all cross-strata have a polymodal 
frequency distribution. High angle and low angle cross- 
strata also have a polymodal frequency distribution (Fig. 

8) . High angle cross-strata have prominant modes between 
135® and 1/1®, between 243® and 261®, skewed to 279® 
and between 297® and 315®, skew'ed to 279® (Fig 8A). Low 
angle cross-strata have prominant modes between 135® 
and 153°, skewed to 171®, between 189° and 207®, 
skewed to 225° and between 297® and 315° (Fig. 8B). 

The mean vector resultant is (Figs 8 & 9): 

• towards 220® for high angle, large scale cross-strata 

• towards 198° for low angle, large scale cross-strata and 

• towards 210® for all large scale cross-strata. 


Interpretation 

High angle, large scale cross-strata are interpreted to be 
the lee-slope foresets of aeolian dunes (following McKee & 
Bigarella 1979, Nielson & Kocurek 1987). Dip directions of 
the high angle cross-strata indicate deposition by SE 
winds, ENE winds and NNW winds (Table 3). Low angle 
cross-strata are interpreted to be predominantly a combi- 
nation of lee-slope foresets, dune (including star dune) 
foot-slope plintns and sand-sheet sets (following 
Ahlbrandt & Frvberger 1981, Kocurek 1981, Nielson & 
Kocurek 1987). 6ip directions are roughly similar to those 
of high ande cross-strata and indicate deposition by SE 
winds, NNE winds, and NW winds (Table 4). Mean vector 
resultants for high angle, low angle, and high angle plus 
low angle cross-strata indicate long-term overall sand 
movement, on average, was from NE towards SW (Table 5; 
Figs 8 & 9). This is opposite to the direction of transport of 
carbonate sands of tW present modern coastal dunes, 
which is towards the NE (Searle & Semeniuk 1985). 


Table 3 


Formative wind directions and predominant direction 
of sand movement for large scale high^ angle 
cross-strata. 


Modal dip directions 
of large scale high 
angle cross-strata' 

Formative wind 
direction 

Direction of sand 
movement 

Towards .306® 

(towards NW) 

From SE 

From SE to NW 

Towards 2.S2* 

(towards WSW) 

From ENE 

From ENE to WSW 

Towards 162®- 144® 

(towards SSE) 

From NNW 

From NNW to SSE 


' Modes arc from Fig. 8 


85 


Journal of the Royal Society of Western Australia 72 (3), 1990 


A. HIGH ANGLE CROSS-STRATA 


306 


288 **- 


270*- 


252‘ 


234 


.72* 


-90* 


108* 


126' 


MEAN VECTOR - RESULTANT 

[direction 220®, length 38.5. consistency ratio 0.33] 


B. LOW ANGLE CROSS-STRATA 


288' 


2702- 


252' 


234 


MEAN VECTOR - 
RESULTANT 

(direction 198® . length 30.5. consistency ratio 0.27) 


C. HIGH ANGLE PLUS LOW ANGLE 
CROSS-STRATA 

North 


D. HIGH ANGLE PLUS LOW ANGLE 
CROSS-STRATA 

North 


324* 


90* 


288 


2702- 


108' 


N = 228 


^ 180* 

MEAN VECTOR - RESULTANT 

(direction 210® , length 65.75, consistency ratio 0.29} 

Angle of dip (degrees) 


252* 


10 
. I ■ 


20 

jJ 


CX 20-29* 
■: 10-19® 

CX 1.5-9® 


number of 
observations 


0 

I . . 1 .1. 


10 


20 

j I 


Figure 8 Dip direction plots of cross-strata in yellow sands of the Perth area. Swan Coastal Plain, southwestern Australia. 
A Rose diagram of dip directions of high angle (equal to or greater than 20®) cross-strata. B Rose diagram of dip directions 
of low angle (1.6-19®) cross-strata. C Scatter plot diagram of dip angles and dip directions for all cross-strata. D Rose dia- 
gram of dip angles and dip directions for all cross-strata. Note A & B are plotted with an arithmetic scale, and not an equal- 
area scale (c/ Nemec 19o8). 


86 


Journal of the Royal Society of Western Australia 72 (3), 1990 


direction of movement. 


Table 4 


Formative wind directions and predominant direction 
of sand movement for large scale low angle 
cross'Strata. 


Modal dip directions 
tif large scale low angle 
cross-strata' 

Formative wind 
direction 

Direction of sand 
movement 

Towards 306® 

(towards NW) 

From SE 

From SE to NW 

Towards 2l6®-l99® 
(towards SSVV) 

From NNE 

From NNE to SSVV 

Towards 1 44® 

(tt>wards SE) 

From NW 

From NW to SE 


Mode'S tire from Fig. 8 


Table 5 


Directions of mean vector resultants for high angle, low 
angle, and high angle plus low angle cross-strata and 
their palaeo-directional interpretations. 


Cross-strata 

Direction of moan 
vector resultant' 

Inierpretatfon 

High angle 

Towards 220® 
(towards SW) 

Overall sand movement is from 
NE to SW under the influence of 
Pleistocene wiitds which were 
predominantly from the eastern 
sector 

l ow angle 

Towards 198® 
(towards SSW) 

Overall sand movement is from 
NNE to SSW under the influ- 
ence of Pleistocene winds which 
were predominanllv from the 
eastern sector 

o’ 

Towards 2I0® 
(towards SSW) 

Overall sand mosement is from 
NNE to SSW under the influ- 
ence of Pleistmene winds which 
were predominanth' from the 
eastern sector 


' Vector reMiltanls <ire from Fig. 8. 


87 


Journal of the Royal Society of Western Australia 72 (3), 1990 


The overall sand movement from NE has many local 
variations (Figs 6 & 7). Sites which are closely located {eg 
10, 11, 12, 13 & 14; Fig. 6) may have a wide cfivergence in 
direction of their dip direction resultants. Furthermore the 
dip directions of individual sites {eg sites 8-14; Fig. 6) are 
also widely divergent, typically over more than .180* . In- 
terconnected (by one or more arms) stellate dune mor- 
phology, plus the associated wide range in dip directions of 
the internal strata of the same features, suggests that sites 
8-14 are located within a linear draa (or megadune) with 
star dunes. This interpretation is important, because the in- 
ternal structures of star dunes are imperfectly known and 
only rarely have they been identified in the sedimentary 
record (Nielson & Kocurek 1987). 

It has been previously suggested elsewhere that yellow 
sand is predominantly glacial age desert-aeolian sediment 
(Glassford & Killigrew’ 1976, Killigrew & Glassford 1976, 
Glassford 1980, Semeniuk & Glassford 1988). Cross-strata 
details (Figs 6, 7, 8 & 9) provide additional support for a 
desert-aeolian origin and are consistent with the following 
refinements to the desert aeolian model in terms of more 
specific formative wind directions. During periods of depo- 
sition of yellow sands. Pleistocene wind directions were 
dominantly from the eastern sector, sub-dominantly from 
the NW and to a minor extent from the W and SVV. 


Horizontal strata 

Description 

Horizontal strata (c 0-1.5® angle of dip) comprise c 13% 
of all strata measured (Fig. 5). As discussed later this low 
proportionate amount is probably an artifact of the lo- 
cation of quarries in hills oi sand rather than sand flats. Sets 
of horizontal strata are up to 7 m thick, and have been 
traced laterally for up to 50 m and, by interpolating discon- 
tinuous outcrop, for more than 100 m (Figs 2 & 3). Hori- 
zontal strata mainly consist of thin to very thin beds and 
laminae (Figs 4C, b & E). Individual strata typically are 
planar. Sets of horizontal strata may be separated by low 
angle stratification (Fig. 4C) and they usually grade lat- 
er^ly into concave-upward low angle strata (Site 9 of Fig. 
3). 

Interpretation 

Large scale sets of horizontal strata are interpreted to be 
dune bottom-set deposits and interdune, aeolian sand- 
sheet deposits formed mainly by grainfall and the move- 
ment of wind ripples, plane beds/laminae and dunes 
across the surface of interdune sand sheets (following 
Glennie 1970, Hunter 1977, Ahlbrandt & Fryberger 1981, 
Kocurek 1986, Lancaster 1988). The movement of sand as 
ripples and plane beds or laminae across sand sheets pro- 
duces horizontal strata during moderate to strong wind ac- 
tion (Bagnold 1941, Glennie 1970, Jopling 1978), In terms 
of this study, the direction of sand transport cannot be in- 
ferred from horizontal stratification. 

Sand flat terrain, if geomorphically anal^ous to the 
sand flats of some desert areas {eg McKee & Tibbits 1964, 
Ahlbrandt & Fryberger 1981), can be expected to be 
underlain predominantly by horizontal strata, and these 
strata would pass laterally into dune terrains underlain by 
cross-strata. That is, cross-stratified dunes typically grade 
laterally into horizontally stratified sano sheets of 
interdune areas (Figs 2 & 3). Quarries located in sand hills 
may be expected to have few horizontal strata. In desert 
ergs cross-stratified dunes and plinths may pass laterally 
into horizonatally stratified interdunes, and both may be 
underlain by horizontally stratified sheets of sand. 


Massive structure 
Description 

Sand units with massive structure have no internal 
stratification. These units occur in three main settings: 
below the present landsurface to a depth of 3-5 m; as thin 
sheets typically 0.5-2 m thick beneath buried 
unconformity surfaces; and up to several metres above the 
w'ater table (Table 2, Fig. 7). Sequences of sand below the 
w'ater table have not been observed in situ. Units with 
massive structure commonly exhibit a range of 
bioturbation features, as will be discussed later. 

Interpretation 

The massive structure of yellow sand is an overprint fea- 
ture and predominantly the product of bioturbation. Thus 
massive yellow sand rnay have originally been stratified. 
This interpretation is consistent with the yellow sand 
dunes and sheets being relict, and with the common as- 
sociation of bioturbation overprints with relict desert 
aeolian deposits (Glennie 1970. Fryberger et al 1979, 
Glassford 1980, 1987; Ward 1988). Buried units of massive 
yellow sand, which are overlain by stratified yellow sand. 
Indicate an alternating history of desert aeolian deposition 
followed by bioturbation during subsequent intervening 
periods of semi-arid or humid conditions. The stratigraphic 
sequence of structures thereby also is consistent with the 
concept of alternations from gfacial age desert phases to in- 
terglacial age humid phases. Such alternations characterise 
the late Cainozoic or many low and middle latitude areas 
of the world (Lamb 1977, Sarnthein 1978, Glassford 1980, 
Thomas & Goudie 1984). 


Major disconformilies 

Description 

Major disconformities occur in 13 quarries (Tables 1 & 2; 
Fig. 7). These disconformities may be within several metres 
of the present landsurface (Figs 2, 3 & 4), but more com- 
monly occur near or disappear below the floor of quarries. 
Disconformities have been traced continuously along 
quarry walls for distances of up to 100 m and by 
extrapolating discontinuous exposures for over 300 m (Figs 
2 & 3). Their obser\'able extent is always limited by the di- 
mensions of the quarry. Deep sequences of yellow sands 
also have more disconformities than shallow sequences. 

Disconformity surfaces are broadly undulose with 
straight planar segments grading to curved segments (Figs 
2, 3 & 4). Straight planar segments may be near-horizontal 
or inclined at angles of up to 15°. Curved segments are 
typically concave-up with maximum amplitudes of 5-6m 
over 50-60m. Disconformities typically have a discordant 
relationship with more than one set of cross-strata. Fur- 
thermore, they also typically separate units of yellow sand 
which are lithologically distinct in terms of structure {eg 
cross-stratified or massive), textures {eg coarser or finer, 
clay-rich or clay pwr), composition and colour {eg reddish 
haematite-pigmented or yellow goethite-pigmented kao- 
lin as coatings on framework grains and as fine sand to silt- 
clay sized grains). Disconformity surfaces within se- 
quences of yellow sands are commonly underlain by a 
tnin, discontinuous sheet of massive white quartz sand 
which typically is several centimetres to a few decimetres 
thick. In places the lower boundary of such sheets has deci- 
metre to metre deep pockets and pipes of white sand, 
5-20 cm in diameter, which taper downwards into under- 
lying yellow sands. 


88 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Interpretation ity surfaces have formed by erosion and soil development 

Discon formities are marked by palaeosols (identified during interstadial or interglacial intervals under semi-arid 

from overprint features; Table 6).' They are buried former or wet conditions similar to the present. Disconformities 

land surfaces, similar to the present vegetated land surface which are not underlain by a palaeosol, but are erosional, 

below which there are pedogenic overprints. These may represent one or more glacial or interglacial intervals, 

disconformities are super-bounding surfaces (Kocurek These disconformities are similar to the first order 

1988), and most are similar to the regional bounding sur- bounding surfaces of Brookfield (1977), and the first and 

face (Talbot 1985) category of super-surfaces. Disconform- second order bounding surfaces of Kocurek (1981). 

Table 6 

Description and interpretation of secondary alteration features, on or within yellow sand, which have overprinted pri- 
mary stratification. 


Overprint feature 

Burrow structure 

Description 

Occurs up to 3-6m below the surface or below deeply btiried surfaces (disconformities); burrow-like structures range from 
less than 1cm to several centimetres in diameter: depending on the plane of section burrows mav be round to cylindrical; 
burrow-fill mav differ from surrounding sand in terms of texture, colour and grain types; burrows have a sharp contact with 
surrounding sand. 

Interpretation 

Burrowing bv various insects, spiders and vertebrates and infilling ol burrows when repeated destroys cross-strata and pro- 
duces a pervasive burrow -mottled structure in detail at the mesoscale. and a massive structure at the macroscale. 

Overprint feature 

Fibrous-root structure (a variety of root structure) 

Description 

Occurs up !o3-f)m below the landsurfaceor3 bm below buried disconformities; thin 0.5- 1cm diameter vertical to branching 
cord-like (dendritic) sand, more coherent than surrounding sand when subjected to subaerial exposure; dendritic sand may 
differ from surrounding vellow sand mainly by being white. 

Interpretation 

Growth of fibrous plant roots displaces cross-strata and following death and decomposition the root channels are infilled 
with sand resulting in a dendritic structure of slightly more coherent sand at a mesoscale; at a macroscale the sand appears 
massive. 

Overprint feature 

Tap root structure (a variety of root structure) 

Description 

Occurs to depths of more than I2m below the present landsurface; tap rwt structures typically arc 5-20cm in diameter and 
this si/e extends continviouslv over vertical distances of more than 12m: the structures arc typically tube-like with a white 
sand nil and ferruginous sand rim; the pijH'-like structures typically have a vertically discordant relationship with horizontal 
strata. 

Interpretation 

Growth bv tap-roots displaces strata: these lap roots act as conduits and sites for solutions and suspensions of iron and alu- 
minium minerals therein- producing multiple vertically discordant pijH»s of white and ferruginous sand. 

Overprint feature 

Colour mottles 

Description 

Occur firstly in a broad ^heet-hke /one up to h-Sm above the groundwater table; secondly in a broad sheet-like /<me up to 
3-8m below the landsurface or buried landsurfaces; mottlin are typically variable in size and shape; mottle diameters range 
from a few mm to several decimetres, mottle shapes range from equant through nipe-like to highly indented amoeboidal; 
mottles are typically vs-hite quart/ sand differing from surrounding yellow sand only in terms of colour and goethite, haema- 
tite and kaolin content 

Interpretation 

Vadose /one and the zone of capillary riseof intermittent wetting and drying and fluctuating Fh and pH in the phreatic zone 
results in differential pedogenic removal of silt-clay sized coatings of goethite, kaolin and quartz from the surface of sand 
grains. 

Overprint feature 

Massive structure 

Description 

Occurs up to 4-6m below the present landsurface and the surface of buried units of yellow sand; may grade vertically or lat- 
erally into units of root-structured and/or burrow-structured yellow sand and/of colour mottled sand. 

Interpretation 

Physical perturbations (cy wetting and drying, removal of fines, settling, compaction) and biological perturbations (cj; root- 
growth, burrowing) de'*l'rov cross-strata by oisrupting and mixing sand layers to form a uniformly homogeneous yellow 
sand 

Overprint feature 

TefTnitarium (or labyrinthoid) structure 

Description 

Occurs up to 2-4m below the present landsurface or below buried landsurfaces of yellow or brown sand/sandstone which 
are relatively rich in silt-clav si/ed goethiti* and/or kaolin; lahvrinthoid structure comprises a tortuous pattern of vermiform 
channels to vesicular voids with brown or vellow sand/sandstone (le/fa- nvri walls and fill; typically weakly coherent; ler- 
mitarium or labyrinthoid structure tvpicaH'v forms a 0.5 to 1,5m thick sheet roughly parallel to the present landsurface. The 
upper surface of this sheet typically is c (f.5-2m below the present landsurface. 

Interpretation 

Termites build a maze of channels with coherent walls, and over time destroy stratification; this results in a sheet of 
labyrinthoid structured sand/sandstone. 


89 


Journal of the Roya! Society of Western Australia 72 (3), 1990 


Overprint feature 
Description 


Interpretation 


Overprint feature 
Description 


Interpretation 


Brown ncKiutos and brown comeniatton to torm sandsiimo roti) 

Occur'i mainly m a shwt like /one between O.S to 2m thick and tend*- to Ih' thicker in mlerdunes; brown to yellowish brown 
ferruginous quart/ sand ntxiules supjxirted in brown to vellow sand or brown ferruginous, massive, labvrmlhoid quart/ 
sandstone; niKluIes consist of quart/ sand suppiiried in a silt-cla\ matrix of goethite. kaolin and quart/; overlies vellow sand 
and underlies white sand; upper Ixiundarv mav be smixith abruptly gradational and broadly parallel with the landsurface 
or interfingered with white sand over vertical cTistances of I 2m. the lower boundary is abruptly gradational to vellow sand 
and roughiv parallel to the upper boundarv. 

Silt-clay si/i*d matrix material and framework gram coatings of gix'thite. kaolin and quart? have been removed from yellow 
sand and transferred in fx»re water solution and suspension and deposited' in the vadose /one mainly as sandv nodules to 
prtxluce brown ncxJular sand: and in the phreatic /one to produce brow n 's.indstone Both i)'pes of overprint are types of 
latcnlii litiriiru^i (locally termed i iiffcr rihk). These /fftmf/i iUtruni>t^ are altered di‘sert-aeolian sediment because they con- 
sist of framework grams of desi^rt-aeolian sand surroundtxl bv remohili/txf and mineralogically partly transformed deserl- 
aeolian dust The overprints supptirt the \ iew of Plavford t'l al ( 197S) that vime /fl/cr/tes in Soutn-westerh Australia are of 
PleLsiocene age. 


VVhite quart/ sand 

White quart/ sand is massive, and is without a gram-surface coating of gcxfthite. kaolin and quart/ of silt-clav si/e. White 
quart/ sand occurs in thnx* stMiings. firstly, it is 1 2m thick where ii occurs within a few metres of the landsurface; secondly, 
it is 0.5m thick where it marks buried former landsurfaces (at disconformihes); thirdly, it occurs near the water table where 
It is c l -4m thick Near the present landsurface while sand thickens from dune lops to dune flanks to interdune flats; it also 
typically overlies brown mxfular vtnd or brown sandstone, and is overlain by humic sand: its uppc*r boundarv is smtx>lh and 
broadly parallel to the landsurface. and gradational into humic sand: its lower boundary is sharp or abruptly gradational, and 
irregular or deeply (l -2m) fH*netrative in the form of I0-30cm diameti*f white-sand filled pqx^s into underlying brown sand. 
The upper boundarv of white saixl In the viemilv of the groundwater table mav be sharp or broadiv gradational into vellow 
sand 

Yellow sand has been transformed to white sand bv removal of grain coatings of goethite, kaolin and quart/ silt-clav in pore 
water solution and susjxmsion 


Overprint feature 


Humic quart/ sand 


Description Massive and fibrous-rix't siructurixl, grev to black quart/ sand with plant debris and silt clav si/ed organic material; the 

quart/ sand generally is not civitcxj with gwthite and kaolin The unit forms a sheet-like cover 0 1 to 2m thick over white 
or vellow sand; it increase's in thickness from Spearw-cHxf Dune ndges and Bassendean Dune lops Into flanks and interdune 
and ndge flaS; humic quart/ sand overlies white or vellow quart/ sand with a gradational contact; its upper boundary is the 
present landsurface, and its lower boundarv is broadly parallel to landsurface. 

Interpretation Yellow or white quart/, sand has been impregnated bv plant debris and silt-clav si/ed organic material to torm a pedogenic 

A-hori/on. 


The occurrence of up to six units of yellow sand separ- 
ated by five major disconformihes (Table 2, Fig. 7) is inter- 
preted as the record of six major glacial-age desert aeolian 
phases and five major interglacial-age semi-arid or humid 
phases in yellow sands of the Perth region. These units are 
most likely only the upper portion of the record of desert- 
aeolian sedimentation in bW Australia (see Logan et al 
1970, Glassford 1980, 1987). 


Features which overprint 
sedimentary stratification 

Sedimentary stratification in yellow sand grades into, 
and generally is gradually obliterated by pedogenic and 
other alteration (or overprint) features (Fig. 10). Overprint 
features include: burrow structures; root-structures; colour 
mottles; massive structure; termitarium structures; cemen- 
tation by brown limonite and clays to form nodules and 
sandstone; removal of yellow or red grain coatings to form 
white quartz sand; and humic infiltration/addition to form 
humic quartz sand (Table 6). The obliteration is gra- 
dational. It decreases downw'ards below the present 
landsurface and beneath buried disconformies, and in- 
creases towards the groundwater table. Furthermore, thin, 
deeply buried disconformity-bounded units of sand lack 
internal stratification, but may be sharply overlain and 
gradationally underlain by stratified yellow sands. These 
relationships indicate that stratification isa primary feature 
and that it is overprinted by a variety of secondary features. 
Bioturbation is further described below. 

Yellow sand from 3 to 5 m below the present land sur- 
face, and sands immediately below the buried surface of a 
disconformity, generally are massive to mottled to vari- 
ously bioturbated. With increasing depth below the pre- 


sent land surface and below buried disconformihes, the 
massive sand eventually grades into stratified sand. 
Quarry walls expose living tap roots, dead tap roots, sand- 
filled tap-root-like structures, and sand-filled to open in- 
sect burrows that penetrate the layered sands, with 
sediment-fills infiltrating from higher horizons. Gra- 
dational sequences, from laminated sand, through lami- 
nated sand with root and burrow structures to mottled 
sand and massive sand, indicate the progression of 
overprinting of stratification predomin«-intly by 
bioturbation (Table 6; Fig. 10). Much of the yellow sand 
therefore records a history of disruption, mixing, and hom- 
ogenizing by biological, chemical and physical processes 
VNmich have overprinted and destroyed primary aeolian 
stratification. 


Discussion and conclusions 

The results of this study have many and far reaching im- 

f ilications. The pervasive occurrence of sedimentary strati- 
ication in thick sequences of yellow sands in the 
Bassendean and Spearwood dunes has implications for the 
origin of these sands. This is because the occurrence of 
stratification supports a primary aeolian origin, and pre- 
cludes an origin w'holly by m situ decaldfication of 
limestones. 

Dip direction resultants of the cross-strata of yellow 
sands indicate winds were dominantly from the eastern 
sector, sub-dominantly from the NW, and to a minor ex- 
tent from the SW and vV. This precludes a wholly coastal- 
marine derivation for vellow sand because the easterly 
component is opposite the SW to NE movement of carbon- 
ate sands of the modem coastal dunes (Searle & Semeniuk 
1985). Presumably the movement of sands that formed 
Pleistocene coastal dunes (now limestone) also was from 


90 


Journal of the Royal Society of Western Australia 72 (3), 1990 


Figure lO Summary diagram of the relationships of cross-stratified yellow sand and secondary overprints. A Alteration 
features which overprint and destroy primary cross-stratification. B Stages in the development of a multistoried sequence 
of intercalated cross-stratified sand, massive sand and major disconformities. For simplicity, zones of humification, 
cementation and bleaching are not shown. 


91 


Journal of the Royal Society of Western Australia 72 (3), 1990 


the SW. An easterly wind direction for yellow sand em- 
lacement is consistent with the occurrence of latest 
leistocene to Holocene lunette dunes, of the Swan 
Coastal Plain, which are located on the western sides of 
lakes {eg Benger Sw'amp, Forresdale Lake, White Lake; see 
Glassford 1980, Beard 1982). 

The seauence of stratified units, representing major 
desert-aeolian phases or ergs, intercalated with the mass- 
ive units beneath major disconformities suggest that the 
yellow sands of the Swan Coastal Plain record a mainly 
middle Pleistocene sequence of desert ergs. During Plio* 
Pleistocene times there have been more than 20 glacial 
periods (Kukla 1977, Lamb 1977, Hooghiemstra 1988) dur- 
ing which high latitude areas of the globe were extensively 
glaciated and sea levels were much lower than at present. 
The middle to low latitudes (such as the presently humid 
SW Australia) then were desertic w'ith winds stronger than 
at present (Lamb 1977, Samthein 1978, Glassford 1980, 
Glennie 1987, Skackleton 1987, Rea & Leinen 1988). Ad- 
ditional desert-erg sequences may be preserved on the 
Yilgarn Block and possibly under the continental shelf of 
Western Australia (Glassford 1980, 1987). 

Stratified yellow sands, bounded by major 
disconformities, thus record mainly middle Pleistocene 
glacial age desert phases, when desert ergs were developed 
on the exposed continental shelf and the ancestral Swan 
Coastal Plain. Glacial age desert-erg phases were separ- 
ated by interglacial age semi-arid to humid phases, with 
their accompanying development of bioturbated 
palaeosols on disconformities. 

Ackmm'lfiif^cments We thank M ) Kriewaldi for critically reviewing the 
manuscript 


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In; Late Cainozoic palaeoclimates of the Southern Hemisphere (ed J 
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Wilde S A & Low G H 1980 Explanatory notes on the Pinjana 1 ;250,000 Geo- 
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93 


V 


INSTRUCTIONS TO AUTHORS 


The Journal publishes (after refereeing) 

• papers dealing with original research done in Western Australia into any branch of the natural sciences; 

• papers concerning some biological or geological aspect of Western Australia; 

• authoritative overviews of any subject in the natural sciences, integrating research already largely published in the 

more specialized national or international journals, and interpreting such studies with the general 
membership of the Society in mind; 

• analyses of controversial issues of great scientific moment in Western Australia. 

Prospective authors of papers in the last two categories should consult the Hon Editor for further advice. 


Contributions should be sent to The Honorary Editor, Royal Society of Western Australia, Western Australian 
Museum, Francis Street, Perth, Western Australia, 6000. Publication in the Society's Journal is available to all categories 
of members and to non-members residing outside Western Australia. Where all authors of a paper live in Western Australia 
at least one author must be a member of the Society. Papers by non-members living outside the State must be 
communicated through an Ordinary or an Honorary Member, Submission of a paper is taken to mean that the results have 
not been published or are not being considered for publication elsewhere. Free reprints are not provided. Reprints may be 
ordered at cost, provided that orders are submitted with the return book proofs. Authors are solely responsible for the 
accuracy of all information in their papers, and for any opinion they express. 


Manuscripts. The original and two copies must be submitted. They should be typed on opaque white paper with 
double-spacing throughout and a 3 cm margin on the left-hand side. All pages should be numbered consecutively, including 
those carrying tables and captions to illustrations, which appear after the text. Illustrations, both line drawings and 
photographs, are to be numbered as figures in a common sequence, and each must be referred to in the text. In composite 
figures, made up of several photographs or diagrams, each of these should be designated by a letter (eg Figure 2B). To avoid 
risk of damage to original figures, authors may retain these until after the paper is accepted. The copies of the figures 
accompanying the manuscript must be of good quality. 

Authors are advised to use the most recent issue of the Journal as a guide to the general format of their papers. Words 
to be placed in italics should be underlined. To facilitate editing, papers must be accompanied by a table of contents, on 
a separate sheet, showing the status of all headings. 

Following acceptance and editing of the manuscript, authors with access to word processors/computers should amend 
their manuscript and forward to the Hon Editor their disk (noting the computer and word-processing program used) and 
one copy of the paper. 


References must be set out as follows: 

Paper Jackson A 1931 The Oligochaeta of South-Western Australia. J R Soc W Aust 17:17-136. 

Twigg L, Majer j D & Kotula R 1983 The influence of fluoroacetate producii^ plants upon seed selection by seed 
harvesting ants. Mulga Res Centre W Aust Inst Technol, Bentley, Ann Rep 6:^-80. 

BooA: Jacobs M R 1955 Growth Habits of the Eucalypts. For Timb Bur, Canberra. 

Chapter in book Dell J 1983. The Importance of the Darling Scarp to Fauna. In: Scarp Symposium (ed J D Majer) W Aust 
Inst Technol, Bentley, 17-27. 

The Title should begin with a keyword. The Abstract should not be an expanded title, but should include the main 
substance of the paper in a condensed form. The metric system (SI units) must be used. Taxonomic papers must follow the 
appropriate international Code of Nomenclature, and geological papers must adhere to the International Stratigraphic 
Guide. Spelling should follow* the Concise Oxford Dictionary. 

Authors should maintain a proper balance between length and substance, and papers longer than 10 (X)0 words would 
need to be of exceptional importance to be considered for publication. Authors will be charged page costs (currently $30 
per page) if papers exceed 8 printed pages. Short papers (2-4 printed pages) are particularly sought as these often ensure 
full use of the 32 pages available in each part. 


Illustrations. These should be prepared to fit single or double column widths. Illustrations must include all necessary 
lettering, and be suitable for direct photographic reduction. No lettering should be smaller than 1 mm on reduction. To avoid 
unnecessary handling of the original illustrations, which are best prepared between 1.5 and 2 times the required size, authors 
are advised to supply extra prints already reduced. Additional printing costs, such as those for folding maps or colour 
blocks, will be charged to authors. 


Supplementary Publications. Extensive sets of data, such as large tables or long appendices, may be classed as 
Supplementary Publications and not printed with the paper. Supplementary Publications will be lodged with the Society's 
Library (C/- Western Australian Museum, Perth, WA 6000) and with the National Library of Australia (Manuscript Section, 
Parkes Place, Barton, ACT 2600) and photocopies may be obtained from either institution upon payment of a fee. 


JOURNAL OF THE ROYAL SOCIETY 
OE WESTERN AUSTRALIA 

CONTENTS VOLUME 72 PART 3 1990 


Page 

Mortality and growth of tree species 
under stress at Lake Toolibin in the 

Western Australian Wheatbelt D T Bell & R H Froend 63 

Motor vehicle emission inventory for the 
Perth airshed T J Lyons, R O Pitts, 

J A Blockley, J R Kenworthy & P W G Newman 67 

Stratification and discon formi ties in yellow 
sands of the Bassendean and Spearwood Dunes, 

Swan Coastal Plain, South-western Australia 

D K Glassford & V Semeniuk 75 


Edited by I Abbott 

Registered by Australia Post— Publication No. WBG 0351 

No claim for non-receipt of the Journal will be entertained unless it is received within 12 months after publication of Part 4 

of each Volume 

The Royal Society of Western Australia, Western Australian Museum, Perth 


The journal of the Royal ScKiety of Western Australia was founded in 1914. Its circulation exceeds 600 copies. Nearly 100 
of these arc distributed to institutions and societies elsewhere in Australia. A further 200 copies circulate to more than 40 
countries. The Society also has over 350 personal members, most of whom are scientists working in Western Australia. The 

Journal is indexed and abstracted internationally. 


A69349/6/89-700 


GARRY L. DUFFIELD. Government Printer. Western Australia 


VOLUME 72 (PART 3)