214 
RIPPLE-MARKS IN SANDSTONE. 
the markings produced by the undulations of water 
on the sand and mud of the shallows and margins 
of lakes, rivers, estuaries, and sea-shores, can hesi- 
tate to conclude, that characters so perfectly ana- 
logous as those observable on the Horsham stone, 
have been produced by a similar operation. When 
a large surface of the stone is cleared from the 
superficial soil which covers it, a most interesting 
appearance is presented, and the spectator is struck 
with the conviction that he is standing on the dried 
shallows of an ancient river. In some places the 
furrows are deep, affording evidence of the water 
having been much agitated, and the ripple strong ; 
in other instances, the undulations are gentle, and 
are frequently intersected by cross ripples, from a 
change in the direction of the waves. On some 
parts of the surface, there are slightly elevated 
longitudinal ridges of sand, made up of gentle 
risings, disposed in a crescent-like manner, and 
these closely resemble the sand ridges whicli are 
produced by the little rills which flow back into 
the sea or river at low water. Some of the slabs 
are covered with thin angular ridges, irregularly 
crossing each other, like the fissures in septaria, and 
which have obviously been caused by deposition into 
crevices made in the sand or mud by drying. A 
considerable portion of the stone, the flat as well as 
the furrowed surfaces, is covered with small cylin- 
drical bodies, which have been moulded in the 
hollows occasioned by some species of vermes. 
Similar forms of a large size also occur ; these 
resemble the trails left by myce^ and have probably 
been produced by some freshwater bivalve. Since 
