120 THE VICTORIAN NATURALIST. 



EXCURSION TO SYDENHAM. 



To the traveller by the Bendigo train the locality around Syden- 

 ham station, formerly knpwn as Keilor Road, does not look very 

 promising for an excursion by members of this Club, but on 

 Saturday, 29th September, about fourteen members and friends 

 detrained there to visit the basalt columns situated on the western 

 branch of the Saltwater River, about two miles north of the station. 

 Looking at a map of the County of Bourke it will be noticed that 

 the Saltwater River forks about six miles above Keilor. The left 

 or eastern branch, heading from near Lancefield, and flowing 

 through Bulla, is generally known as the Deep Creek, while the 

 right or western branch, rising in the Dividing Range west of 

 Macedon, is known under a variety of names, such as Gisborne 

 Creek, Macedon River, Jackson's Creek, and Saltwater River. 

 About two miles above the junction, in a bend of this branch 

 which adds a north-easterly prolongation to section 29, parish 

 of Maribyrnong, the cliff with the columns is situated, though, 

 being on the opposite bank of the stream, it is really in section 

 10 of the parish of Tullamarine. The district was geologically 

 surveyed by Aplin some forty years ago, and though on the 

 Quarter Sheet No. 7, S.E., he made the note "Symmetrical 

 basaltic columns 50 to 60 feet in height," the spot seems quite 

 unknown to Victorian geologists, notwithstanding that it is not 

 more than 16 miles by road from Melbourne, and within easy 

 walking distance of a railway station. Leaving the station and 

 making our way across the plain, from a slightly more elevated 

 portion a number of volcanic hills or vents were seen to stretch 

 across the north-western and northern horizons, no doubt the 

 sources of the extensive basaltic formation over which we were 

 walking, and which extends right down to the shores of Port 

 Phillip. Crossing the Mt. Alexander road about three-quarters of 

 a mile on the Melbourne side of the Holden Inn, we followed a 

 well-used track leading down into the valley, and ending nearly 

 opposite the cliff. Though the valley is almost destitute of trees, 

 yet in the springtime, when the grass paddocks and the crops on 

 the hillsides are vividly green, it affords many pretty bits of 

 scenery, being really a deep, winding gash cut through the basalt 

 of the Keilor Plains. We estimated its depth by barometrical 

 readings at about 170 feet, and the bed of the stream as being 

 about 220 feet above sea level. 



The basalt of the plains is a thin sheet, and cliff sections show 

 that it flowed over almost level sands, probably of Miocene age. 

 These sands in their turn lie on an almost level surface of up- 

 turned Palaeozoic rocks, which are either Silurian or Ordovician, 

 it is not known which. Where the valley displays sections of 

 this nature there is nothing very striking about the basalt — it 



