Prof. Morris — Boring Mollusca in Oolites. 271 



deposit. In some places the shells of oysters may be observed at- 

 tached to the surface of the Carboniferous limestone on which the 

 oysters lived, and these are occasionally pierced through by the 

 borers, which found such shells remaining on the rocks after the 

 animals which had constructed them had died, as we now observe 

 on many sea-coasts." Further 1 we " have direct evidence that in 

 some places, after a certain amount of accumulation and a bed had 

 been formed, there was a state of repose, for in the upper part of 

 some beds of the Inferior Oolite, succeeding each other, the surface 

 has been bored by the same lithodomous animals which pierced the 

 surface of the subjacent Carboniferous limestone or Lias conglomerate, 

 as the case may be. The fact is, doubtless, somewhat general in this 

 part of the district, and is valuable, not only as showing the repose 

 between the accumulations constituting the different beds, each in 

 succession being sufficiently consolidated to permit the boring 

 animals to establish themselves on its upper surface, but also as 

 pointing to the probable consolidation of many a bed in other parts 

 of the Oolite series, prior to the deposition of another above it, where 

 this kind of evidence cannot be adduced." 



With regard to the false-bedding, one of the characteristic features 

 of the Forest Marble, and one by which it may be contrasted with 

 the beds of the upper zone of the Great Oolite, showing a marked 

 change in the nature of marine conditions, coincident with the 

 introduction of this formation, 2 De la Beche remarks, 3 " The beds 

 known as the Forest Marble frequently exhibit a minor mixture of 

 fine detritus ; probably thrown down from mechanical suspension, 

 with broken shells, fish palates, broken pieces of wood, and oolitic 

 grains, sometimes strewed horizontally, but very frequently in a 

 diagonal manner, showing the sweeping of loose materials on the 

 bottom into a minor depression. Sometimes the sandstone is marked 

 by ripple or friction ridges and furrows, and crossed by the tracks 

 of marine animals which had crawled over the surface, one surface 

 beneath the other at short depths, so that we have the markings of 

 sea-bottom over sea-bottom. Such false-bedded accumulations of 

 shells and grains of oolite with drifted pieces of coral, are not 

 uncommon in other parts of the Oolitic series, being observable in 

 the Great Oolite about Bath, in the Inferior Oolite of some localities, 

 and in other parts of the series, which exhibits, as a whole, many 

 minOr alterations of sea-bottom, a large proportion of the limestones 

 being composed of the hard parts of marine animals, a character 

 wherein they differ very materially from the Lias limestones." 



Brief as the above remarks are, it may be observed that there are 

 many points of geological interest to be studied in the quarries around 

 Cirencester, with regard to the physical and organic conditions under 

 which the various strata were accumulated, the clay-beds due to fine 

 mud thrown down from mechanical suspension, the sands to the 

 drift of heavier detrital matter, and the limestones to the accumula- 

 tions of shells, oolitic grains and corals (sometimes seen as coral 



1 De la Beche, ibid. p. 291. 2 Hull, Memoir, ibid. p. 72. 



3 De la Beche, Memoir, ibid. p. 285. 



