366 WILMORE : THORNTOX, MARTON AND BROUGHTOX-IN-CRAVEX. 
There is some secondary iron -hydrate, very soft and con- 
cretionary. It replaces both crinoidal limestone and the black 
limestones mth cherts. 
Many of the bedding planes show the characteristic lium- 
mocky surfaces, especially where there are thin and somewhat 
irregular shale bands with occasional crushed fossils. These 
shale bands have, in places, the appearance of having been 
in part squeezed out. 
Searching for fossils has proved rather laborious work. 
Occasionally in the quarrying operations (local road metal), 
one may see on the fractured surfaces impressions of brachiopods 
Fig. 4. 
SKETCH OF A PIECE OF LIMESTONE 18 INCHES BY MNE INCHES, WITH 
CHERT BANDS. 
and other fossils. Crinoid stems are more frequent. At one 
time, in the Marton Scar Quarry (25), I saw quite a number 
of impressions of Productus pustulosus and P. semireticulatiis. 
Usually, however, I have not been very fortunate, and I have 
turned over great quantities of broken road metal with very 
little result. 
There are other ways of obtaining fossils, however. As 
mentioned in the case of the Marton-Broughton beds, Avhen 
a quarry has been deserted for years the exposed surfaces often 
show fossils. The fine calcareous cement, made up of foramini- 
fera and comminuted fragments of corals, enchinodermata, and 
