The South Australian Naturalist. 



is shown diagrammatically in the aeeompanying' sketeh. The 

 rocks here provide us with three separate and distinct chapters 

 of past history, from tertiary (Janjukian) time right up to the 

 present day. ' These three chapters of earth history are not 

 lengthy chapters, '"as the earth views time." Also, they are 

 comparatively late chapters in the long story. 



Chapter A— The Time of the Great Murray Gulf.— Taking 

 the earliest chapter first, we shall deal with the beds marked A 

 in the sketch. These horizontally bedded layers of rock form 

 part of the thick and widespread yellow limestones that are 

 found throughout nearly the whole course of the Lower ^lurray. 

 These beds are well shown in the cliffs that run almost without 

 a break on both sides of the river — either rising abruptly from 

 the water's edge, or else bounding the river flats a mile or so 

 back from the main stream. A close examination shows that 

 some of the layers are packed Avith the relics of once-living 

 animals. We found some of these layers, well known to palae- 

 ontologists, up to a foot or more in thickness, and consisting of 

 a packed mass of oyster shells, cemented together by clay and 

 lime carbonate; whereas most of the more beatitifuUy-shaped 

 shells of other species have dissolved away, leaving only tlie 

 casts or impressions, the oyster shells are completely preserved. 



Among other fossils collected froui these beds are sharks" 

 teeth, lish relics, crabs, corals, sea-urchins, sea-worms, and 

 abiuidant types of shell-fish. The imiform level bedding of these 

 limestones is evidence of their having been de})Osited tnider 

 Welter. The nature of the fossils shows that the water was salt, 

 for all the animals represented are sea-dwellers. The Avide ex- 

 tent of (piite similar continuous beds shoAvs that the Murray 

 cliff's are portion of a rock deposit laid doAvn in a great gulf 

 that extended from the Moimt Lofty Ranges eastAvards to the 

 \'ictorian Grampians, and as far back almost as Broken II il! 

 and AlburA' . This one-time sea is knoAvn as the ' ' I\Iurray Gulf. 

 The exact species found tell us the "date" Avhen this great gulf 

 Avas in existence, but such date cannot be giA^en in terms of 

 years. It Avas, hoAve\^er, long, long antecedent to the appear- 

 ance of man on the earth. This, then, is the first chapter of our 

 cliff' story, and a Avonderful ehapter it is. 



Chapter B — A Bend of the Ancient Murray. — Just as 

 novelists may alloAv a period of time to elapse betAveen Iavo 

 successiA^e chapters, so here Ave have a long break in the story. 

 The line separating the beds A and B is no less eloquent than 

 the fossil-bearing rocks themseh^es, for it tells of a long period 

 of time, during Avhich the sea receded, the limestone deposits 



