Sedimentary Geology, 14 (1975) 191--218 © Elsewer Scientific Publishing Company, Amsterdam -- Printed m The Netherlands
P A L E O C U R R E N T S IN T H E P L I O - P L E I S T O C E N E S A M R A F O R M A T I O N (JERICHO REGION, ISRAEL) AND THEIR TECTONIC IMPLICATION
Z.B. BEGIN
Geologzcal Survey of Israel, Jerusalem (Israel) (Received September 4, 1974, rewsed and accepted May 23, 1975)
ABSTRACT Begin, Z.B., 1975. Paleocurrents in the Pho-Plelstocene Samra Formation (Jericho regmn, Israel) and their tectonm lmphcation. Sediment. Geol , 14 191--218 The Pho-Plemtocene Samra Formation, cropping out within the Jordan Rift Valley near Jericho, was laid down in a fluvlo-deltam environment Cross-bedding measurements show that the main paleocurrent was directed NNE, in contrast to the present E and SE drainage direction. A NNE--SSW ridge is therefore assumed to have exmted within the Rift at Phocene--Eearly Pleistocene times, diverting the drainage NNE.
INTRODUCTION A l t h o u g h well k n o w n in general, the t e c t o n i c e v o l u t i o n o f the Dead Sea Rift Valley since the N e o g e n e is difficult to f o l l o w m detail. The d i f f e r e n t c o n t i n e n t a l s e d i m e n t s - - m a i n l y clastics - - t h a t have filled t h e Rift, are n o t easily c o r r e l a t e d due to lack o f guide h o r i z o n s and i n d e x fossils. One w a y o f d e c i p h e n n g the d i f f e r e n t stages o f the Rift d e v e l o p m e n t is r e c o n s t r u c t i n g the changes m its p a l e o g e o g r a p h y a c c o r d i n g to s e d l m e n t o l o g m a l evidence, and the s c o p e o f this p a p e r m t o use such evidence, observed in o u t c r o p s o f the S a m r a F o r m a t i o n near J e n c h o . The S a m r a F o r m a t i o n is a Plio-Pleistocene clastm unit, c r o p p i n g o u t within the Dead Sea Rift, and also m its i m m e d i a t e s u r r o u n d i n g s (the J u d e a n Desert), b e t w e e n the D e a d Sea area ( B e n t o r and V r o m a n , 1 9 6 0 ) , and Lake T i b e n a s ( d e f i n e d t h e r e as the N a h a r a y i m Gravel - - Picard, 1 9 4 3 ; Fig. 1). Pmard ( 1 9 4 3 ) c o i n e d the t e r m S a m r a Series, its t y p e locality being H i r b e t e-Samra 6 k m NE o f J e r i c h o ( C o o r d i n a t e s 1 9 5 8 / 1 4 5 8 , Israel Grid: Outcrop 1 m Fig. 2). The S a m r a Series was briefly described by Pmard {1943} as a 6 - - 1 0 m t h i c k section, consisting o f c a l c a r e o u s sandstones, i n t e r c a l a t i o n s o f c a l c a r e o u s marl, and a f l i n t - - p e b b l e c o n g l o m e r a t e at the top, overlain by the Llsan F o r m a t i o n (Lartet, 1869). Picard c o r r e l a t e d these beds with hm f o r m e r " O o l i t m F o r m a t i o n " (Picard, 1931} e x p o s e d west o f J e r i c h o ( C o o r d i n a t e s 1 9 1 4 / 1 3 4 5 : Outcrop 3 m Fig. 2), 0.7 k m west o f the J o r d a n Rift marginal
192 350
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fault, and with other out c r ops of coarse clastlcs m the Jordan Valley south of Jericho where it is overlain by the Llsan FormaUon (Coordinates 1 9 5 5 / 1 3 4 8 ; Outcrop 2 m Fig. 2). See also R ot h (1970). Pmard (1943) interpreted the Samra Series as representing river deltas, flowing into a lake which e x t e n d e d from the Dead Sea to the vicinity of Bet She'an. B en to r (1960) and B ent or and Vroman (1960) ascribing the rank of a f o r m a t i o n to the Samra Series, also m t e r p r e t e d ]t as a fluvlo-hmnic sequence. The detailed t y p e secUon of the Samra F o r m a t i o n at its t y p e locahty (as suggested by Picard, 1943) is given by Begin (1974) (Fig. 3). In the o u tcr o ps studied, the Samra F o r m a t i o n rests u n c o n f o r m a b l y on either the Senonian Mishash For m aU on (Shaw, 1947) or the Senonian--
pp. 193--194
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Maastrichtian Ghareb Formation (Shaw, 1947) both of the Mount Scopus Group (Flexer, 1968). The Samra Formation is slightly (about 5 ° to the NE) tilted at Outcrop 1 (Fig. 2). THE SAMRA F O R M A T I O N N E A R JERICHO
The Samra Formation in the Jericho area consists of bedded calcarenite, conglomerate, gravels, some calcareous silt and some beds of oolitm hmestone. The clastic components are mostly limestone, chert and phosphorite of older, Turonian and Senonian formations of the Judea and Mount Scopus Groups (Arkin and Hamaoui, 1967; Flexer, 1968). Of mineral grams, some quartz, rutile and zircon were observed, although no detailed mineralogical study was made. These minerals also may have been derived from Turonian rocks (Weiler and Sass, 1972). The textures of the clastic sediments are highly variable, particles size ranges from fine silt to boulders 30 cm long. Roundness of particles also varies from well rounded to angular. The calcarenites are in most places well sorted to moderately well sorted (Friedman, 1962). The conglomerates show poor sorting, the pebbles c o m m o n l y appear to be floating in a sandy matrix. The thickest measured section, of about 35 m, is exposed in Outcrop 1, at Coordinates 1943/1454 (Fig. 2). The Samra Formation rests here unconformably on the Mishash Formation. At the base there are angular pebbles above which is a brown calcilutite with some gypsum, containing the foraminifer A m m o m a beccarru and the ostracod Cypndeis httoralis which are brachsh-water species (defined by V. Klug and A. Rosenfeld, G.S.I.). This is overlain by 4 m of laminated calcilutite and calcarenite. Above these the clastic sediments are coarse calcarenite and conglomerate, marly calcilutlte and a bed of grain-supported oolitic limestone. The calcarenites and conglomerates are for the most part well lithified by a calcareous matrix. However, m Outcrop 1, beds of the upper part of the section are only slightly lithified. The transitmn from one type to the other is gradual. In Outcrop 1, the lower, lithified part was subdivided into two units, A and B, separated by a terrace (Plate Ia). The upper unconsolidated u m t was designated as Umt C (Fig. 3).
Age o f the Samra Formation According to the general geologmal setting, the Samra F o r m a t m n was attributed to the Early Pleistocene (Samra Period) by Pmard (1943), and also by Bentor and Vroman (1960). This is partly supported by the occurrence of a marine brackish-water fauna m the lower part of the formation near Jericho, suggesting its correlation with other sediments found along the Jordan Rift Valley as far south as Ha-Makhtesh Haqatan (Fig. 1), which contain marine or brackish foraminifers and represent a Neogene (probably Phocene)
198
PLATE I
199
ingressmn into the Rift Valley (Schulman, 1959; Shat3ar et al., 1966). The marine-brackish environment was then disconnected from the Mediterranean Sea and turned into a lake environment. However, it should be noted that the faunal assemblage for itself is n o t an accurate stratigraphic indmator since a similar assemblage was found in the Raham Conglomerate, which may be of Middle Miocene or even older age (Garfunkel et al., 1973). The Samra Formation is overlain by the limnm sedtments of the L s a n Formation, the deposition of which started about 60,000 years B.P. (Kaufman, 1971). Thus sedimentation of the Samra Formation near Jericho started in the Neogene, and must have ended before Late Pleistocene. SEDIMENTARY STRUCTURES
The most c o m m o n sedimentary structure within the Samra Formation is tabular cross-bedding (see Table I). The inidividual sets are think -- up to 3 m (Plate Ic). Horizontal stratification, large-scale trough cross-bedding (Plate IIc), scour-and-fill structures and ripple marks are also present. Contorted lamination of the calcarenites -- up to 2 m in size -- are c o m m o n m Outcrops 1 (Units A and C) and 2 (Plate III) (Begin, 1974). Most of these are convolute structures (Ten Haaf, 1956) and some are recumbent-folded cross bedding (Allen and Banks, 1972) (Plate IVa). Two large-scale structures are c o m m o n in Outcrop 1, where both Units A and B are exposed so that they may be observed m plan-vmw. The crossbedded sets form up to 1 m high, elongated ridges, perpendmular to the direction of the cross-beds. They may be followed for some tens of meters, and are usually straight but sometimes slightly smusoldal (Plate IIa,b). Another conspicuous large-scale structure in this area is a 5--10 m high, 100--200 m wide ridge, built of gravels of Umt C. The ridge has an arcuate form m plan view (Fig. 4), by which " e x t e r n a l " and " i n t e r n a l " zones may be defined. In cross-section, this ndge shows a characteristic structure (Plate Ib and Fig. 5): the core is made up of low-angle cross-beds, dipping " o u t w a r d s " northeast and east of the ridge crest, and dipping "rewards" southwest and west of it. The margins of the ridge are made up of high-angle cross-beds, also dipping " o u t w a r d s " along the " e x t e r n a l " margins of the ridge and dipping "inwards" along the internal margins.
PLATE I a O u t c r o p 1, U m t s A a n d B, divided b y a wide t e r r a c e ( l o o k i n g n o r t h w a r d s ) b. O u t c r o p 1, U n i t C, s h o w i n g i n t e r n a l s t r u c t u r e of the ridge, w i t h Its gently d i p p m g c o r e and steeply dipping margm (looking westward) c. Large scale c r o s s - b e d d i n g set of clarenite, t r u n c a t e d a n d overlain by a large-scale set of c o n g l o m e r a t e ( O u t c r o p 1, U n i t A)
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a. A straight transversal bar (Outcrop 1, Unit B). b. A sinusoidal transversal bar (Outcrop 1, Unit B). c. Large-scale trough cross-bedding (Outcrop'l, Umt A).
Cross-bedding measurements --procedure A t o t a l of a b o u t 4 0 0 m e a s u r e m e n t s o f f o r e s e t dip a z i m u t h s were t a k e n s e p a r a t e l y for each stratigraphic u n i t in t h r e e o u t c r o p s (Fig. 5). Each out~ c r o p was subdivided i n t o 0.5 × 0.5 k m 2 quadrangles, and t h e m e a s u r e m e n t s in each quadrangle were g r o u p e d a c c o r d i n g t o the stratigraphic u n i t in which t h e y were observed. F o r each such q u a d r a n g l e the v e c t o r m e a n a z i m u t h (0), t h e r e s u l t a n t v e c t o r length (R), the v e c t o r m a g n i t u d e m p e r c e n t (L%) (Curray, 1 9 5 6 ) and the variance c a l c u l a t e d a r o u n d t h e v e c t o r m e a n (S 2 ) were determined.
202
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T h e e x l M e n c e ol a r a n d o m c h s t n b u t l o n w i t h i n a q u a d r a n g l e wa.~ t e s t e d lr~ u s i n g L ' , m t h e R m l e l g h t e s t I C u r r a y . 1 9 5 6 , his tlg 4~ o r b y u s i n g H '~ ~,: n u m b e r o f m e a s u r e m e n t , ) l D u r a n d a n d G r e e n w o o d , 1 9 5 8 , t h e i r fig. 1~ I~,, t h e s m a l l s a m p l e s A f t e r a s c e r t a i n i n g b y t h a t m e t h o d t h a t a p r e f e r r e d one~l.t a u o n d o e s e x t s t , t h e m e a s u r e m e n t s o f e a c h s u c h q u a d r a n g l e w e r e groupe,~ a r o u n d t h e v e c t o r m e a n m t w e l v e 30 - s e c t o r s . m t h e s e q u a d r a n g l e , t h e w,ct o r m e a n is t h e b i s e c t o r o f o n e o f t h e 30 -~ectors, n o t n e c e s s a r i l y t[le m o ( t a I o n e . In t h o s e q u a d r a n g l e s , w h e r e n o s l g m f l c a n t p r e f e r r e d o r i e n t a t i o n w a , f o u n d , m e a s u r e m e n t s w e r e g r o u p e d m 3 0 - s e c t o r s s t a r t i n g a r b i t r a r i l y fron~ t h e n o r t h (Fl~. 6 L
203 P L A T E IV
a Recumbent-folded cross bedding (north on right) (Outcrop 1, Umt A) b Asymmetrm ripple marks (NE on left) Note cross-bedding at the upper part of the photo, and the boulder m upper left (Outcrop 1, Unit C)
The rose-diagrams m Fig. 6 are o f equal-area t y p e , m which the s e c t o r areas are p r o p o r t i o n a l t o the n u m b e r o f m e a s u r e m e n t s {and n o t to t h m r p e r c e n t a g e m the sample). This reflects the w i t h i n - o u t c r o p v a n a b t h t y , giving d u e w e i g h t to sample size. M e a s u r e m e n t s o f each o u t c r o p were g r o u p e d t o g e t h e r ; at O u t c r o p 1 t h e y were g r o u p e d a c c o r d i n g to stratigraphm units. New v e c t o r m e a n s and o t h e r p a r a m e t e r s were e s t a b h s h e d for each u m t or o u t c r o p . M e a s u r e m e n t s were
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Gravels I a _o Upper Conglo . . . . A Low er Conglomerate I u~ ~ /i 2 rnl Mishash Formatlor/ L~ I[ ~ ] ] Sechon :n Fig 5 I -- -Boundary of the Ridge t of Unit C 0 5Kml Road
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205
rearranged around the particular vector mean (Fig. 7), and presented in equal-area rose diagrams representing percentages. An attempt was made to fit a circular normal curve to each of the larger samples (Gumbel et al., 1953; Pincus, 1953: Gumbel, 1954; Curray, 1956).
OUTCROP
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1~040" - AzErnuth of vector-rne~n, n Number of observGtlons L - Vector magnltude s- - V o m o n c e ( e r o u n d t h e vector meGn)
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N u m b e r of Meosuroments Unit C
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1950
Fig. 6. Cross-bedding directions data, Outcrop 1 (figure continued on p. 206).
J 1960
206
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T h e p a r a m e t e r k was t a k e n a c c o r d i n g to the p a r U c u l a r L f r o m G u m b e l et ,~1 (1953, t h e i r table 1} a n d the e x p e c t e d f r e q u e n c m s f r o m their table 3. T h e t~." of the t h e o r e t m a l curve was e x a m i n e d by testing the o b s e r v e d frequenclt,.against the e x p e c t e d ones for each 30 -sector using a X 2 test ( C u r r a y . 1956~ (See AppendLx ).
Analysts o/ the dtrectto;zal data Cross- beddtng Outcrop 1. T h e o u t c r o p area is a b o u t 3 k m : a n d the d a t a p r e s e n t e d ~.,,
Fig. 6 s h o w t h a t the w i t h i n - o u t c r o p variability is considerable. Howeve~ m o s t o f t h e s u b - s a m p l e s s h o w a v e c t o r m e a n m the n o r t h e r n q u a d r a n t s . B~ distinguishing b e t w e e n the t h r e e s t r a t l g r a p h m u m t s m this o u t c r o p , ~t b e c o m e ~ clear t h a t while a n o r t h to n o r t h e a s t d i r e c t i o n ~s characteristic o f Unit :~ (Fig. 7a}, a n o r t h to w e s t d i r e c t i o n ~s c h a r a c t e r i s t i c o f U m t B (Fig. 7b}..'~ s o u t h - s o u t h w e s t d~rectlon is 'also p r o m m e n t in U m t A. F o r each o f t h e s e d i s t r i b u t i o n s , as well as f o r their c o m b i n e d d i s t r i b u t i o n . a c i r c u l a r - n o r m a l c u r v e was fitted. T h e d i s t r i b u t i o n s are n o t c i r c u l a r - n o r m a l ones with p a r a m e t e r s as e s t i m a t e d ( G u m b e l , 1 9 5 4 ) f r o m t h e s a m p l e s lse~' A p p e n d i x 1. U n i t C, w h e n g r o u p e d a c c o r d i n g to quadrangles, s h o w s m s o m e cases a,
207
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203 n o r t h e r n m e a n d i r e c t i o n and m o t h e r cases no p r e f e r r e d o n e n t a t : o n It s h o u l d be n o t e d t h a t the directional data o f Un:t A, :n quadrangles 2, ; and 8 is c o n s i d e r e d statistically m s l g m f l c a n t {Le. n o preferred orlentatlon~ a l t h o u g h p r e f e r r e d o r i e n t a t i o n s ( b : m o d a l ) are clearly present. This arlse~, f r o m the fact t h a t the existence of a preferred o r i e n t a t i o n :s tested by Ubln{~ the length o f the r e s u l t a n t v e c t o r as a p a r a m e t e r . However, t w o o n e n m t l o m , 180 " apart, t e n d to annul each other, and the result is o f an a p p a r e n : r a n d o m n e s s o f orientations. A t t e m p t i n g to o v e r c o m e that difficulty these. t h r e e samples were g r o u p e d together. The resultant rose d m g r a m ~Fig. 7d~ s h o w s t w o o p p o s i n g d o m i n a n t m o d e s , m the NE and SW quadrant,~ The same is true for U m t C. The data t a k e n along the ridge (see above} ,~' t h a t unit, were separated a c e o r d m g to l o c a t i o n ; those taken "lnmde'" Lhe t~m were separated f r o m those taken " o u t s i d e " it {See Fig. 7e,f}. These al,~, s h o w t w o s u b - p o p u l a t : o n s , the w, c t o r means of winch are a b o u t 180 apart
.Isymmetrtc ripple mark.~ ~Plate IVb} Small scale a s y m m e t r i c ripple m a r k s were f o u n d within Unit (" ,d Outc r o p 1 ( C o o r d i n a t e s 1941/1.172). T h e y strike 1 4 5 - - 3 2 5 - and their leesld~ dips 0 5 5 ° (Plate III). This indicates a n o r t h e a s t e r l y c u r r e n t direction
Recumbent [olded cro.~s-beddmg {Plate IVa~ Such a s t r u c t u r e , the height o f which is a b o u t 1 m, was f o u n d m t r o t .1 o ~ O u t c r o p 1 ( C o o r d i n a t e s 1 9 4 4 / 1 4 5 5 t . The fold axis, striking E - ~ , , is opel, t o w a r d s the n o r t h . Tins indicates a n o r t h w a r d c u r r e n t d i r e c t i o n qAllen and Banks, 1972). ENVIRONMENT OF DEPOSITION S ~ d llTI e f t ~fl F3/ S [ I'U ¢2tu r e . ,
In o r d e r to s p e c : t y the e n v i r o n m e n t m which the S a m r a F o r m a n o n ~t~d e p o s i t e d m the J e r i c h o region, the assemblage of s e d : m e n t a r y structure,,, was c o m p a r e d t o t h a t of m o d e r n e n v i r o n m e n t s . T w o possible analogues arc the delta and the braided-stream e n v i r o n m e n t s lbee Table I }. C o m p a r i s o n o f the Samra F o r m a t i o n to the delta e n v i r o n m e n t a~ d~. scribed by C o l e m a n and (lagllano ( 1 9 6 5 ) showa a very g o o d a~reemenl especially with s e d i m e n t a r y s t r u c t u r e s c o n s i d e r e d typical o f the d l s t n b u t a r ) c h a n n e l and its i m m e d i a t e ~surroundmgs {subaenal a n d s u b a q u e o u s levee~l The w h o l e assemblage o f the S a m r a F o r m a t i o n s e d i m e n t a r y structures appear m these areas. The only d i s c r e p a n c y :s the absence o f t h i c k beddmR so a b u n d a n t m the S a m r a F o r m a t m n -- f r o m these e n v i r o n m e n t s C o m p a r i s o n o f the S a m r a F o r m a t i o n to r e c e n t braided streams also show~great similarity (Table [), a l t h o u g h the relative a b u n d a n c e o f structures t a b u l a t e d and r a n k e d by the a u t h o r -- is only q u a h t a t l v e and m a y serve a~ a m e r e indication.
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210
(Train-size parameter,,
T h i r t y - e i g h t grain-size analyses w e r , m a d e on samples f r o m san0y bed~ :, the S a m r a F o r m a t m n at O u t c r o p 1. Of these, 19 analyses o f samples Iron lIthffmd ealcaremtes o f Umt A (some of t h e m t a k e n f r o m the ,am,, b~,t were d o n e by measuring gram sizes in thin sections using whole-ph~ intervals T w o h u n d r e d m e a s u r e m e n t s were taken f r o m each thin seet~om and ti:~ c u m u l a t i v e f r e q u e n c y curves were c o r r e c t e d a c c o r d m g to F r m d t n a n ' , ( 1 9 5 8 ) fig. 8. The o t h e r 19 samples were t a k e n f r o m loose calean,nite , ' U m t C (all samples t a k e n f r o m a vertical mterval o f some 3 m ~ dn,t wen sieved a c c o r d i n g to s t a n d a r d m e t h o d s in half-phi intervals. Gram-size p a r a m e t e r s were c o m p a r e d (Van de Graaf, 1 9 7 2 ) to the ,tm~ dards e s t a b h s h e d for recent s a n d y e n v m o n m e n t s by F n e d m a n tl.967t an( M m o l a and Welser ¢1968). The p a r a m e t e r s used were Folk and Ward', ( 1 9 5 7 ) G r a p h m Mean, lncluswe G r a p h w S t a n d a r d D e w a t m n . and tht Inch~ sive G r a p h : c Skewness. The scatter dmgram of these p a r a m e t e r s are s h o w n m Fig. b. hi ,&e MeaJ D i a m e t e r versus S t a n d a r d Deviation diagrams, 'all p o i n t s fall w~thm Mo~ol, and Wemer's " R i v e r " d o m a i n o f the diagram and 80% o f them fall wLthn F r i e d m a n ' s "'River" d o m a i n . The scatter is s o m e w h a t less obwou.- m t h . Skewness versus S t a n d a r d Deviation Diagram, where 85~/~ of the polnks fal within Moiola and Welser's " ' R i v e r " d o m a i n and o n l y 70% within Frledmm~ " R i v e r " d o m a i n . This scatter dmgram, h o w e v e r , is c o n s i d e r e d a weaker ~n¢t: c a t e r t h a n the f o r m e r by M o m l a and Wetser (1968~. It m a y be c o n c l u d e d t h a t a c c o r d i n g to the textural character~,~tlc~ ~t~, Samra F o r m a t : o n should be regarded as a " r i v e r " sediment. It l, ~t~gge~t.et, t h a t the deposits are either the actual ones o f the river or tha: tiw~ ~ , r , d e p o m t e d rapidly into the lake e n v i r o n m e n t w i t h o u t u n d e r g o i n g r~,-.~ortlng ~. a shore e n v i r o n m e n t . The l a t w r possibility implies either steepl3 .dopm'~ edges o f the lake or d e p o s i t i o n by turbid~tes
('ollcllZSlOtl
Both s e d i m e n t a r y structures and f~raln-slze p a r a m e t e r s indicate a lluvtd tile-deltam e n v i r o n m e n t el d e p o s i t i o n . In analogy to m o d e r n f l o o d s u h w ~ are t o d a y c h a r a c t e n s t m o f the semi-arid J u d e a n Desert, o n e m a y ~uppo~t t h a t in b o t h fluvlatfle and deltaic e n v i r o n m e n t s high velocity flow's with hig|~ load c o n c e n t r a t i o n s o c c u r r e d i n t e r m i t t e n t l y . During times o f low ~ ater |ew,, in the lake, the emerging delta m a y b e c o m e a braided stream and wee ver,a The presence of a b r a e k : s h - w a t e r f a u n a (see abovel and oolltw hmebtum, m d m a t e t h a t the beds of the Samra F o r m a t i o n were at least m t e r m l t t e n ~ l \ submerged.
211 I N T E R P R E T A T I O N OF T H E D I R E C T I O N A L D A T A
A c c e p t i n g a fluvio-deltam o n g m f o r the S a m r a F o r m a t i o n , m e a n s t h a t t h e f o r e set a m m u t h s m e a s u r e d within the f o r m a t i o n m d m a t e t h e m a r e p a l e o c u r rents t h a t p r o d u c e d it. It was s h o w n b y S n n t h {1972) t h a t m a s t r a i g h t 2.1 k m reach o f a m o d e r n b r a i d e d s t r e a m (a size c o m p a r a b l e to O u t c r o p 1 m t h e s t u d m d area) p l a n a r foresets a z i m u t h s o f transversal bars a l o n e are widely dispersed (L = 42.4%, S ~ = 5,073). T h e v e c t o r m e a n , h o w e v e r , a c c u r a t e l y ldentlfmd the direction of the mare channel complex. T h e s e results are m a c c o r d a n c e with t h o s e o b t a i n e d f r o m t h e s t u d m d area (Fig. 7a--c). D e s p i t e t h e i r wide dispersion, t h e r e f o r e , t h e v e c t o r m e a n s are t a k e n as i n d i c a t o r s of t h e d i r e c t i o n s o f the m a r e c h a n n e l ( w h e t h e r fluvial or deltaic) m w h m h these s e d i m e n t s were d e p o s i t e d . T h e grand v e c t o r m e a n f o r O u t c r o p 1 is 013' with L = 36.9% (333 meas u r e m e n t s ) This m a y t h e n be t a k e n as an e s t m l a t e o f the d i r e c t i o n o f the m a i n c h a n n e l c o m p l e x m O u t c r o p 1. An a d d i t i o n a l 75 m e a s u r e m e n t s f r o m O u t c r o p s 2 a n d 3 yield a very close grand t o t a l v e c t o r m e a n (010' , with L = 32.1f~.} which is t a k e n as the e s t i m a t e d c h a n n e l d l r e c t m n in the s t u d i e d area. T h e o t h e r d i r e c t i o n a l d a t a , n a m e l y a s y m m e t r i c ripple m a r k s a n d r e c u m b e n t - f o l d e d c r o s s - b e d d i n g also p o i n t t o a similar f l o w direction. The p i c t u r e is, o f course, m o r e c o m p l e x w h e n e x a m i n e d m detail. T h e e x i s t e n c e o f a w e s t w a r d m o d e o f Unit B (Fig. 7b) and a s o u t h - s o u t h w e s t ward m o d e in Unit A (Fig. 7a) p o s e s s o m e a m b l g u l t m s . T h e simplest e x p l a n a t i o n o f the s t r o n g NW v e c t o r m e a n o f U m t B is t h a t the N N E c h a n n e l prevailing during d e p o s m o n o f U m t A was s u b s e q u e n t l y r e p l a c e d by a WNW d i r e c t e d chalmel. T h e low, N N E - e l o n g a t e d ridges, perp e n d i c u l a r to the f o r e s e t dips (see a b o v e ) are t h e n i n t e r p r e t e d as transverse bars o f t h a t channel. An a l t e r n a t i v e e x p l a n a t i o n is t h a t Unit B m i g h t h a v e b e e n d o m i n a t e d b y longitudinal bars. In such bars, which are e l o n g a t e d s t r e a m w l s e , the m a r e cross s t r a t a are o r i e n t e d at great angles ( u p to 90~) t o the local s t r e a m d i r e c t i o n (Wllhams, 1 9 7 1 , his fig. 11). A p p l y i n g Wflham's o b s e r v a t i o n to t h e c o m b i n e d m e a s u r e m e n t s o f Units A and B at O u t c r o p 1 (Fig. 7c), t h e westward m o d e m a y be i n t e r p r e t e d as originating f r o m a N N E flow, p r o d u c i n g p e r p e n d i c u l a r o r i e n t e d cross-beds in l o n g i t u d i n a l bars. These c o m p r i s e s o m e 3074 o f the t o t a l m e a s u r e m e n t s (AppendLx A). T h e s e c o n d d i f f i c u l t y is the s o u t h - s o u t h w e s t m o d e o f U m t A. Since the main f l o w d i r e c t i o n is N N E , this m a y be t h o u g h t to reflect changes o f flow r e g i m e c a u s e d by tidal c u r r e n t s I Kleln, 1 9 6 7 , De R a a f and B o e r s m a , 1971). A l t h o u g h at least part of the s e d i m e n t s in the s t u d i e d area are o f d e l t m c origin, such an e x p l a n a t i o n is n o t v e r y plausible, t a k i n g i n t o a c c o u n t the small size o f the lake m which these s e d i m e n t s were lind d o w n . Still an a l t e r n a t i v e e x p l a n a t i o n Is t h a t this m o d e r e p r e s e n t s b a c k s e t crossb e d d i n g (Power, 1961). Such u p s t r e a m inclined internal l a m i n a t i o n is re-
212
p o r t e d f r o m h e l d studies of a n c i e n t s e d i m e n t s ( P o w e r , 1 9 6 1 ; H a n d et ai.~ 1 9 6 9 ; S k i p p e r , 1971), L a t e H o l o c e n e ( B o e r s m a e t al., 19681, a n d recenl s e d i m e n t s ( H a r m s and F a h n s t o c k , 1 9 6 5 , t h e i r p l a t e 1; T a y l o r et al.. 1971 ) a~ well as f r o m e x p e r i m e n t a l studies ( M l d d l e t o n , 1 9 6 5 ; J o p l i n g a n d Rlchardsoh~ 1966). A l t h o u g h H a r m s and F a h n s t o c k ( 1 9 6 5 ) , M l d d l e t o n ( 1 9 6 5 ) a n d Skip p e r ( 1 9 7 1 ) suggest t h a t a b a c k s e t c r o s s - b e d d i n g is t y p m a l l y low angled, P o w e r ( 1 9 6 1 ) as well as H a n d et al. ~1969) r e p o r t b a c k s e t cross-beds to dip as high as 25 '~ and 24 ~ respectively. High dips o f b a c k s e t cross-beds m a 3 . p e r h a p s , be a s s o c i a t e d w~th the o b s e r v a t i o n t h a t t h e y are s o m e t i m e s d e p o s ~ted on the u p s t r e a m , s t e e p e r slope o f b a c k f l o w ripples ( B o e r s m a et a l , 1968). Q u a d r a n g l e s 2, 7 a n d ~ o f O u t c r o p 1 s h o w an o b w o u s b~-modal~ty w~t~ m o d e s 180 ° a p a r t iF~g. 7d). T h e SSW s u b - p o p u l a t i o n ( a s s u m e d "'backbet'" cross-bedding) has an average m c h n a t m n o f 22.2-' ( M a x m m m 40 ~ while the " f o r e s e t " N N E ones have an average m c h n a t l o n o f 14.7 '~ ( M a x m m m 33 , D e s p i t e t h e s e high values for b a c k s e t d~ps, this e x p l a n a t i o n s e e m s to be m o t plaumble t h a n t h e first one. PALEOGEOGRAPHY TECTONICS
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T h e p r e s e n t base level ot the s t r e a m s m the J e r i c h o area Is the Dead Sea. and all s t r e a m s run m an e a s t w a r d to s o u t h e a s t w a r d d t r e c t l o n f l o ~ m g i n t o ~ K n o w i n g t h a t the s o u t h e r n D e a d Sea area was rapidly subsiding m Ph,~ P l e i s t o c e n e tmles ~Zak, 1967), an e a s t w a r d or ~ o u t h e a s t w a r d p'aleocurrelJ~ d i r e c t i o n s h o u l d t h e n be e x p e c t e d f o r t h e S a m r a channels. H o w e v e r . th~ S a m r a F o r m a t i o n m the J e r i c h o area was d e p o s i t e d b y a wide c h a n n e l m which f l o w was d i r e c t e d essentially N N E 0.e. a 9 0 ' - d e v i a t i o n o f the e, p e c t e d trend). This implies t h a t east o f the S a m r a F o r m a t m n o u t c r o p s , t h e r e existed at t h a t t i m e a ridge which d i v e r t e d t h e flow NNE, t o w a r d s a dfffereH~ base level. A l t h o u g h this ridge d o e s n o t exist t o d a y - since it was d o w n f a u l t e d ante has b e e n c o v e r e d by the y o u n g e r s e d i m e n t s of the L~san F o r m a t m n -- ~t stil! s e e m s possible to r e c o n s t r u c t it: It ~s a s s u m e d t h a t the ridge was o n c e ,n~ a n t i e h n e , lying east o f the B u q e ' a s y n c l i n e ( R o t h , 1970). O u t c r o p 3 o f ttw S a m r a F o r m a t i o n actually hes on the axis o f t h a t s y n c h n e (F~g. 9). R e c o ~ s t r u c t m g t h a t ax~s by c o n t i n u i n g its t r e n d t o w a r d the NE s h o w s t h a t Out c r o p 1 m~ght also have been l o c a t e d w~thm t h a t s y n c h n e , a n d t h a t O u t c r o p 2 hes on the c o n t i n u a t i o n o f ~ts e a s t e r n flank. T h e NW f l a n k o f t h a t s y n c h n e is i n d e e d o b s e r v e d at O u t c r o p 1 (F~g. 9t, w h e r e a s ~ts c o n t i n u a t i o n with the NW f l a n k o f the B u q e ' a s y n c h n e was already n o t e d by P m a r d (1931). C o n m d e r m g t h a t t o p o g r a p h y follows stru(. t u r e an m o s t cases m s o u t h e r n Israel and m the J u d e a n Desert, a n d a s s u m m ~ t h a t the B u q e ' a s y n c l m e has c o n t m u e d NE w~thout changing e~ther the t r e n d and p l u n g e of its axis or the dip o f its eastern flank, such a flank c o u l d have
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9. A structural contour map and referred structural axes ]n the study area
formed the NW slope of an elongated, NE trending ridge. Such a ridge could h a v e s e r v e d as t h e e a s t e r n b a n k o f a w i d e b r a i d e d s t r e a m , i n t e r m i t t e n t l y s u b m e r g i n g m l a k e w a t e r t o f o r m a d e l t a in w h m h t h e d o m i n a n t f l o w w a s
214 n o r t h - n o r t h e a s t w a r d ; T h e closely c o n c u r r e n t o r i e n t a t i o n o f the a s s u m e d p a l e o c u r r e n t a n d the t r e n d o f t h e B u q e ' a s y n c h n e axis s u p p o r t s t h a t a s s u m p t i o n (Fig. 9). T h e o c c u r r e n c e o f s e d i m e n t s o f the S a m r a F o r m a t i o n at Out~ c r o p 2, m a y be e x p l a i n e d by a s s u m i n g a local s t r u c t u r a l low while the poss~bfllty o f a p r e - S a m r a t o p o g r a p h i c l o w d u e to e r o m o n s h o u l d be e x c l u d e o since t h e S a m r a f o r m a t i o n lies here on the high stratlgraphlc level o f th, ~ Ghareb Formatmn. T h a t the base level o f s t r e a m s in the J e r i c h o area was n o t necessarily the low-lying s o u t h e r n D e a d Sea at t h a t time, is suggested by c h e c k m g the t h i c k n e s s of t h e N e o g e n e - - Q u a t e r n a r y alluvial fill o f t h e D e a d Sea Rift Vailey. S o m e 10 k m NE o f t h e D e a d Sea its t h i c k n e s s is o n l y 276 m t d n l l e d m the " J o r d a n Valley 1'" drfllhole, see Neev and E m e r y , 1967). Thlb is vel3 thin as c o m p a r e d t o the 6 , 0 0 0 m e s t i m a t e d for t h e a l l u w a l - - e v a p o r m c ~e q u e n c e m the s o u t h e r n D e a d Sea (Zak, 1967), o f w h i c h 3.7 k m were actually drilled (E1-Llsan drillhole: Neev a n d E m e r y , 1967). T h e area n e a r ~'Jordm~ Valley 1 " was n o t , then, a site of t,h m k a c c u m u l a t i o n m N e o g e n e - - Q u a t e r n a r y t~me. T h a t the a m o u n t of s u b s i d e n c e of the R i f t Valley f l o o r n e a r ,Jericho ~: small, as c o m p a r e d to t h a t m the s o u t h e r n D e a d Sea r e g m n , is also e v i d e n c e d by a small o u t c r o p of the M a a s m c h t l a n G h a r e b F o r m a t m n f o u n d m the. c o u r s e o f this s t u d y s o m e 4 k m east of the Western R i f t m a r g i n s tCoord~ n a t e s 1 9 5 7 / 1 3 4 6 ) . T h e p r e s e n c e of a shallow f l o o r w i t h i n the Rift m thl~ r e g m n is also suggested b y gravity m e a s u r e m e n t s ( K n o p o f f and Belshe. 1 9 6 5 ) , s h o w m g n o n e o f the negative a n o m a l i e s t y p m a l o f the Rift m th~ S o u t h e r n D e a d Sea regnon {Zak, 1 9 6 7 ~. On t h e o t h e r h a n d , m o r e ~han 6 0 0 n: think clastms and e v a p o r i t e s are r e p o r t e d f r o m G r a m S a b t (Fig. 9t (Iomde~ a n d Blake, 1 9 3 9 ; a c c o r d i n g to Bender, 1968, o n l y 350 m o f L o w e r Plelst,('~ cene clastlcs - - G h o r - e l - Q a t a r Series -- c r o p o u t there). This o u t c r o p hes un the axis o f t h e B u q e ' a s y n c h n e , as r e c o n s t r u c t e d above, a n d m a y represen~ the a n c i e n t base level of the S a m r a F o r m a t m n n e a r Jericho. All these o b s e r v a t i o n s m a y well be e x p l a i n e d by a s s u m i n g t h a t the style (~ d e f o r m a t m n , c o n s l s t m g of e l o n g a t e d N E - t r e n d m g s y n c h n e s and a n t m l m e a . w h m h is so t y p i c a l f o r the J u d e a n Desert, c o n t i n u e d e a s t w a r d into the are:~ o f the p r e s e n t - d a y J o r d a n Valley. As a s c e r t a i n e d m the n e a r b y S a r t a b a are,t ( B m y a m i m , 1 9 7 3 , see Fig. ] ), these s t r u c t u r e s were f o r m e d m a i n l y prior t,~ t h e Middle E o c e n e . Since s e d i m e n t s of E o c e n e age were p r e s e r v e d m a i n l y m t h e ~ynchnes ~,~ t h e r e g m n , the o c c u r r e n c e of L o w e r E o c e n e s e d t m e n t s in " J o r d a n Valley 1". b e l o w the alluvial fill (Neev and E m e r y , 1967), suggests t h a t this s~te hes a l r e a d y east o f the a n t m h n e a s s u m e d above. T h e d o w n - f a u l t m g o f t h e a s s u m e d e a s t e r n ridge o c c u r r e d a f t e r the depos~t m n o f t h e S a m r a F o r m a t m n . This t e c t o m c p h a s e is e v i d e n c e d by tilting ot the elastic beds at Grain S a b t ( I o m d e s and Blake, 1 9 3 9 : Bender, 1968~ A l t h o u g h the age o f the f a u l t i n g can be d e t e r m i n e d o n l y w i t h i n t h e r a t h e r b r o a d t i m e limits w h m h c o u l d be fixed f o r t h e S a m r a F o r m a t i o n isee above~
215
Unit A 0 A=031"
n=162 K=I 40 The theorehcol c u r v e slgnfflcantty deports from the observed ,~ frequencies
50
OA2 ~
50
30
OA1 '~
OA1 =031" OA 2 =211" KAI =KA2 : 3 0 hAl= 130 nA2:32
3o
ii 0 Ammuth
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r
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~
240" 300" 000. 060" -e-
r
120" '
~
~
O~
AA1 ' 2
A mu
180.
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060" i
1½0.
-b-
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3O
n =114 K=107 The theoret,col curve signff,cantty deports from the observed
I~
I I
J J 1 I~
OB 1
10
0
OB2 eB1-284" {}B2:031' KBI=KB2=30 nB2:33 nB1 = Bl
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AzMmuth 180" 240" 300" 000" 060" -c-
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Az,mutt~ 150'' 240'' 3;0.' 0;0'' 0;0.' 120" -d-
Units A+B OA+B=O04"
1! 60
n =276 K=092 The theorehcol curve slgn, ficontly deports from the observed frequencies
w
>., 4O
OA2=211" OB1=26&" OA1=OB2:031"
6o
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.
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20
o Azimuth 160" 240" 300" 000. 060" 12o° -e-
160°
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Azq°muth 1;0'' 2'0" 300" 06o" 0;0" 120" -f-
Fig. 10. C i r c u l a r - n o r m a l c u r v e fitting. L e f t - - a c c o r d i n g to parameters as e s t i m a t e d from t h e s a m p l e . R i g h t - - a c c o r d i n g t o freely e s t i m a t e d parameters, a s s u m i n g t w o p o p u l a t i o n s . (see A p p e n d i x ) .
216
it must have occurred sometime m the Pleistocene, before the depositmn ot the Llsan Formation 60,000 years B.P. ACKNOWLEDGEMENq
The manuscript was critically revmwed by Mr. Y. Arkln and Dr. (k Poppe~ of the Geological Survey of Israel and Prof. R. Freund and Dr. Y, Weller (~ the Hebrew Univenty of Jerusalem, Department of Geology. Their helpfm suggestions are gratefully acknowledged. Thanks are due to Mr. E. Ram f()~ technical assistance, APPENDIX
CIRCULAR-NORMAL
CURVF
FITTING
T h e ( h s t r f l ) u t l o n el lit tin, n , e a ~ u r e m e n t s oi U n i t s A a n d B a t O u t c r o p ~, as welt a b o t h o f t h e m c o m b i n e d , ~s ~hov~n m F i g 7a c F o r e a c h o f t h e s e a c l r c u l a l - n o n n ~ d curv~ wa~ h t t e d I F,g. 10). T h e dlsl, r l b u t l o n s a r e n o t c ~ r c u l a r - n o r m a l o n e s w i t h p a r a m e t e ~ e s t i m a t e d ( G u m b e l , 1 9 5 11 f r o m ~he ~ a m p l e s In U m t A, t h e s o u t h w e s t e r l y m e a s u r e m e n I ~ ~ e d u c e t h e v e e t o l m a g m t u d e latl(i t h e r e f o r e also t h e p a r a m e t e r k ( G u m b e l et a l , 1 9 5 3 1 , a n d t h e r e s u l t ,.- t h a i t h e e x p e , - t e ( t w d u e fo~ t h e m o d a l s e c t o r Is t o o l o w h , U m t B tt~ c h s c r e p a n c y b e t w e e n o b s e r v e d a n d e x p e c t e d v a l u e s arises f r o m a s e e o n d a r } m o d e lit t h t n o r t h e a s t d i r e c t i o n , cau.~nlg a ( l o c k - w i s e s h i f t o f t h e e x p e c t e d v e c t o r m e a n T h i s b m o d a h t y also e f l e c t s t h e c o m b i n e d , U n i t , \ a n d U n i t B, d l ~ t r i b u t m n b G r e a t a n a l y t m a l d f f f m u l t m s arise m a t l e m p t m g t o s e p a r a t e a n o b s e r v e d c i r c u l a r dlstr~ b u t t o n r o t e t w o s y m m e t ~ l c . t l p m l~ w~th b y e p a r a m e t e r s , 0 1 , 02, k l , 1~2 a n d ~ t ( = N - ~'z ( G u m b e l , 1 9 5 1 ) . All a t l c m p t w,t~ m a d e t o . , e p a r a t e t h e a b o v e m e n t i o n e d ( h s t r ~ b u t l o n : r o t e t w o s y m m e t r i c a l ()lleS~ I) 3 freel 3 e s t i m a t i n g t h e i r p a r a m e t e r s n 1, n 2. t)~ e y e , ,m~ a s s u m l l ! g a c o n s t a n t te -- '! 0 Io) all el t h e m In U m t A (Fig. I b), (]A1 w a s t a k e n e q u a l i,. (l x (F~g. l a ) . (J-x2 w,ls t,~ken ,~ ~ts ,lntlp~,de In U m l B IF~g l d ) , 0B1 W~k~ tJkel~ a ~ t h m o d e b~secto~ a n d 0 B 2 ,~ cqUdt 1(} l),\ T h e r e s u l t i n g t h e o r e t i c a l cur~e~ m e s h o w n m F~g. l b , l d a n d [1 X 2 t e s t s s n o w e d th,,. t h e s e t h e o r e t i c a l v a l u e s ,,~*, m ~ > t g m f m a n t l 3 d i f f e r e n t (at t h e 0 0 5 level) l r o t n t h e oI, s e r v e d v a l u e s T h o u g h el c o u i s e ~hese a l e n o l tile b e s t fits, a n d t h e i r p a r a m e t e r s are m u d o f s u b j e c t , r e n a t u r e , t h e 3 ~ e e m ~o i n d i c a t e t h a t tile o b s e r v e d d i s t r i b u t i o n s m a y be (:, plamed by some sm~ple a~sumpi~(,n~
REFERENCES AJten, J . R . L a n d B a n k s , N . L . , 1 9 7 2 . A n i n t e r p r e t a t i o n a n d a n a l y m s o l r e c u m b e m t o t d e c d e f o r m e d ~ r o s s b e d d i n g . S e d m l e n t o l o g . ' , , 19 2 5 7 28 1 A r k m , Y. a n d l l a m a o u , , M., 1 (,)t;2. rl'h~, J u d e a G r o u p ( U p p e r C r e t a c e o u s ) m ( ' o n t r a l a m , S o u t h e r n Is, ael. ( f e e l S u l v 1-t Bull., 12 l'i p p B e g i n , Z . B . , 1 9 7 5 T h e g e o l o g 5 m t h e ~ m m l t 3 o f J e r m h o . G e o l . S u r v . Isr. Bull i m p r e s s , Beg, n, Z . B . , m p r e p a r a t i o n L a r g e ~cale c o n v o l u t e b e d d i n g m t h e S a m r a F o r m a t i o n (Ne~, g e n e - - Q u a t e r n a r y ) nero J e r , c h o , l~rael Bender, F , 1968 Geologic ~on Jordamen B e l t r a g e z u r R e g l o n a l e n G e o l o g i c d e r Erd,. Gebruder BorntraegeJ, Berhn, 230 pp B e n t o r , Y . K . , 1 9 6 0 L e x , q u e S t l a t l g r a p h l q u e I n t e r n a t i o n a l . r e ] III, A s m , [*asc 10C~ I~rael. C e n t r e N a t i o n R e e h S(u , Paris, 151 p p B e n t o r , Y . K . a n d V r o m a n , A., 1 9 6 0 . G e o l o g m a l M a p el I~rael, I 1 0 0 , 0 0 0 , ser,ea A, T h , N e g e v , S h e e t l 6, M o u n t S d o m , 117 p p
217 Boersma, J.R., 1967. Remarkable types of mega cross-stratification in the fluvlatlle sequence of a subrecent dlstnbutary of the Rhine. Amerongen; the Netherlands. Geol. Mijnbouw, 46. 217--235. Boersma, J.R., Van de Meene, E.A. and Tjalsma, R.C., 1968. Intrmated cross-stratification due to interaction of a mega ripple with its leeside system of backflow ripples (upper-pomtbar deposits), Lower Rhine Sedlmentology, 11: 147--162. Coleman, J.M., 1969. Bramhaputra River: channel processes and sedimentation. Sediment. Geol., 3 129--239. Coleman, J.M. and Gagliano, S.M., 1965. Sedimentary structures: Mississippi River deltaic plain In G.V. Middleton (Editor), Primary Sedimentary Structures and their Hydrodynamic Interpretation. Soc. Econ. Paleontol. Mineral. Spec. Publ., 12 133--148. Curray, J.R., 1956. The analysis of two-dimensional ormntatlon data. J. Geol., 64 117-131. De Raaf, J.F.M. and Boersma, J.R., 1971. Tidal deposits and their sedimentary structures (seven examples from Western Europe). In. J.D. de Jong (Editor), Sedimentology; Research on Sedimentology and Sedimentary Geology in the Netherlands. Geol. Mijnbouw, 50' 479--503. Doeglas, D.J., 1962. The structure of sedimentary deposits of braided rivers. Sedlmentology, 1. 167--190. Durand, D. and Greenwood, J.A., 1958 Modlfmation of the Raylelgh test for uniformity m analysis of two-dimensional orientation data. J. Geol., 66. 229--238. Flexer, A., 1968. Stratigraphy and facies development of Mount Scopus Group (Senoman-Paleocene) in Israel and adjacent countries Isr. J. Earth-Sci., 17. 85--114. Folk, R.L. and Ward, W.C., 1957. Brazos River bar: A study in the slgnifmance of gram size parameters. J. Sediment. Petrol., 27. 3--26. Friedman, M.J., 1958. Determination of stove size distribution from thin-section data for sedimentary petrological studies. J. Geol., 66. 294--416. Friedman, M.J., 1962. On sorting, sorting coefficient and the lognormahty of the gram size distribution of sandstones. J. Geol., 70. 737--756. Frmdman, M.J., 1967. Dynamic processes and statistical distribution of beach and river sands. J. Sediment. Petrol., 37. 327--354. Garfunkel, Z., Bartov, J., Eyal, Y. and Steinitz, G., 1973. Raham Conglomerate -- new evidence for Neogene tectonism m the southern part of the Dead Sea Rift. Geol. Mag., 111: 55--64. Gumbel, E.J., 1954. Application of the circular normal distribution J. Am. Stat. Assoc , 49 217--297. Gumbel, E.J., Greenwood, J.A. and Durand, D., 1953. The circular normal distribution, theory and tables. J. Am. Star. Assoc., 48: 131--152. Hand, B.M., Wessel, J.M. and Hayes, M.D., 1969. Antldunes m the Mount Toby Conglomerate (Triassic), Massachusetts. J. Sediment. Petrol., 39' 1310--1316. Harms, J C and Fahnstock, R.K., 1965. Stratification, bed forms and flow phenomena (with an example from the Rio Grande). In: G.V. Mlddleton (Editor), Primary Sedimentary Structures and Their Hydrodynamic Interpretation. Soc. Econ. Paleontol Mineral. Spec. Publ., 12: 84--115. Ionides, M.G. and Blake, G.S., 1939. The Water Resources of Transjordan and their Development. Government of Transjordan, 372 pp. Jopling, A.V. and Richardson, E.V., 1966. Backset bedding developed in shooting flow laboratory experiments. J. Sediment. Petrol., 36. 821--825. Kaufman, A., 1971 U-Series dating of Dead Sea basra carbonates. Geochim. Cosmochim Acta, 35 1269--1281. Klein, G D., 1967. Paleocurrent analysis in relation to modern marine sediment dispersal patterns. Am. Assoc. Pet. Geol. Bull , 51: 366--382. Knopoff, L. and Belshe, J.L., 1965. Gravity observation of the Dead Sea Rift. In: T.N, Irvme (Editor), The World Rift System. Geol. Surv. Can. Pap., 66-14" 5--21.
21~ Lartet, L , 1869. Essal sur la geologic de la Palestine. Annal. Se.. Geol., 1 0 - I 13 MeKee, E . D , Crosby, E.J. and Berrgh.ll, M L., 1967. F l o o d deposits, BIjou ('reek, C o h rado, J u n e 1965. J. Sedm~ent Petrol., 37 8 2 9 - - 8 5 1 . M l d d l e t o n , G V., 1965 A n t l d u n e c r o s s - b e d d i n g in a large f l u m e J S e d i m e n t Petrok, ,;." 922--927 Molola, R.J and Welsel, D., 1968 Textural p a r a m e t e r s , an evaluation I S e d i m e n , P e t r o l , 3 8 45--53 Neev, D. and Emery, K rj., 196, T h e Dead Sea, d e p o s l t l o n a l processes anti cn~lronmell,,. o f evaporites Geol. Sure. ist Bull No. 41 147 pp. Pleard, L., 1931. Geological R e s e a r c h e s in the J u d e a n Desert 108 p p Picard, L., 1943. S t r u c t u r e and E v o l u t i o n o f Palestine Bull Geol Dep t l e b r e w Um~ Jerusalem, IV ( 2 - - 4 t : 1--34 Plncus, H.J., 1953. The analysis o f aggregates ol o r i e n t a t i o n data in the Earth bClel:lCe~ Geol , 61 181--502 Power, W . R , 1961. Backset beds in the (~oso F o r m a t i o n , I n y o C o u n t y I'allfornla S e d i m e n t Petrol., 31 6 0 3 - - 6 0 7 R o t h , I., 1970 Wadi-El Qilt, (;eoto~lca] Map 1 50,000 Geological SUl'~e3 ot lsrae, Jerusalem S c h u l m a n , N , 1959 The Geol(n,W o f the (~entral J o r d a n Valley Bull Res. C o u n c l s r , '~t 63--90 Shahar, Y , Relss, Z. and Gerry, E., 1966 A new o u t c r o p of m a r i n e N~,o~ena in li'~ Negev. isr. J. Earth-Sci.. 15 82--81 Shaw, S . H , 1947. S o u t h e r n Palestine, Geological Map on a scale ot 1 250,000 ~ltt, e x p l a n a t o r y notes. G o v e r n m e n t o f Palestine, Jerusalem, 43 pp Skipper, K., 1971. A n t i d u n e c r o s s - s t r a t i f i c a t i o n in t u r b l d i t e s e q u e n c e C l o r o d o r i n e ~)~ m a t l o n s , Gaspe, Q u e b e c Sedlmentolog:y, 17 51--68 Smith, N.D., 1970. The braided s t r e a m d e p o s l t l o n a l e v l r o n m e n t c o m p a r i s o n ol t h e Pia~t~ River w g h s o m e Silurian rocks, N o r t h Central Appalaehlan. Geol Soc . \ m Bull ~ b, 2993--301 1. S m i t h , N D , 1972 S o m e s e d i m e n t o l o ~ i c a l a~peets o f planar cross s t r a t l f l e a t a m in a MtlI(t, brmded river J S e d i m e n t Petrol., 12 62 1--63-1 Taylor, G., Crook, K.A. and Woodger, W D , 1971 U p s t r e a m f o r e s e t cross-stl'atiflca'~lOi~ origin and l m p h e a t m n s for p a l e o s l o p e analysis. J. S e d i m e n t . Petrol , t l 57~--58J Ten Haaf, E., 1956. Significance, ol c o n v o l u t e l a m i n a t i o n GeoI M i j n b o u w , Nleuwe ,';*'r 18 1 8 8 - - 1 9 1 Van de Graaf, F R., 1972 l:lu~lal deltaic l a c m s o t t h e C a s t e t ~ a t e S a n d s t o n e l C r e t a c e o u . , East-Central Utah. J S e d i m e n t Petrol. 1 2 : 5 5 8 - - 5 7 1 Weiler, Y. and Sass, E., 1972 Karstic S a n d s t o n e b o d i e s in the T u r o m a n l i m e s t o n e s ~, Judea, Israel. S e d i m e n t Geol , 7 137 152 Williams, G . E , 1971 F l o o d deposit> ol the sand bed e p h e m e r a l s t r e a m s of Cent'-,, Australia. S e d l m e n t o l o g y , t 7 1--- 140 Williams, P.F. and Rust, B . P , 1969 The bedimentoloa;y o f a b r a i d e d riw,r ,1 Se(htnen Petrol., 39 6 4 9 - - 6 7 9 Zak, I., 1967. The Geology ot M o u n t S d o m Thesis H e b r e w Unlv Jerusalem 2 0 8 p p ~!'. H e b r e w with an English a b s t r a c t )