Ordovieian Rocks at Daylesford. 169 



of slate crosses the sandstone, about 3 feet thick, almost to the 

 slate bed below. The sandstones above and below this band 

 differ somewhat in texture, and numerous apparently detached 

 slate fragments occur below the slanting band. Following this, 

 the sandstone is largely cut away by local faults, and a hollow 

 formed, which is filled by a confused mass of slate and sandstone 

 fragments, the bed above also entering the hollow and being 

 highly contorted, this contortion extending beyond the limits of 

 the hollow. Beyond this the sandstone seems to resume a 

 texture similar to that before the slanting band of slate. In the 

 southern end of the band, and the mixture which enters the 

 hollow in the sandstone below, the appearance presented is that 

 of a conglomerate of slate fragments in sandstone, though many 

 of the apparently isolated fragments of slate are no doubt really 

 united. 



A number of slate fragments enclosed in sandstone can be seen 

 in the next cutting towards Daylesford, somewhat angular in 

 outline and up to 9 by 2| inches in size. 



At first sight the explanation might be suggested that the 

 whole of the results might be due to deposition of somewhat 

 plastic clay lumps with the coarse sand, accompanied by contem- 

 poraneous erosion of the underlying beds. A more detailed 

 examination at once shows this to be untenable. One of the 

 anost conglomeratic patches is in the hollow of the sandstone 

 below, which could not have remained open unsupported. It 

 also fails to explain the gradual change to parallel bands of slate 

 and sandstone. The alternative is that this is a pseudo-con- 

 glomerate, formed by breaking up of once continuous beds, and 

 subsequent examination revealed all that was necessary to 

 support this view. 



Unequal thickening and thinning of slate beds between sand- 

 stones may be noticed in almost any" railway cutting in the 

 Ordovieian rocks in this district. Slate beds are seen to be often 

 completely interrupted on the exposed face. The variation in 

 thickness and interruption is often connected with the jointing 

 and other cracks in the neighbouring sandstone, and occasionally 

 with small local faults. Sometimes the slate gradually thickens 

 and abruptly stops at a joint or fracture in the sandstone. Con- 

 tortion of the laminae is noticed in some of these cases. 



8a 



