3()f) m:\\ vokiv state musefm 



jrt til iat ill's — m ^rrouj) of (•('pli;iln]i(i(l iiiolhisUs with ;i coiled slicll in whieli 

 the inarLrins of tlic si'i>la (»r siitiiri's are coiiiplicated by siiui>le lobes 

 and saddles. It is not a natural trronp 



greywacke — an old name for gray arenaceous and ai-trillaccons rocks — not 

 niucli used 



grit — a silicious sandrock with ooarse grains — something between a sand- 

 stone and a conglomerate. It is often loosely used for either 



gyroceracone — a conic shell (cephalopod) coiled in a loose spiral in a 

 single plain, as a watch si>ring 



hiatus — an unrepresented interval 



hinge area — the flattened area margining the hinge of brachiopod or pele- 

 cypod shells 



horizon — ixjsitiou in the geologic time scale 



hydrocorallines — a group of marine organisms building coral-like struc- 

 tures, but lacking some of the essential structural characters of corals 



hyponomic sinus — the marginal sinus or depression in the rim of the living 

 chamber of cephalopod shells corresponding to the iwsition of the 

 swimming organ or hyponome 



hyi)ostoma — the lip or movable plate of varying form attached to the under 

 rim of the trilobite head, and behind which is situated the mouth 



impervious — impenetrable to whaler 



incise — cut down into, as a river cuts into a plateau 



index fossil — fossils which mark a special horizon irrespective of the nature 



of the sediment 

 inface — the cliff portion of a cuesta i. e. the part facing the old land 

 inner lowland — the belt of lowland or valley country lying between the 



inface or front of the cuesta and the old land 

 insequent stream — streams beginning as runs over the edges of a clitT, 



where they cut a gully w'hich gradually becomes elongated 

 intercalation — insertion between 

 interseptal — occurring between the septa 

 interspaces — spaces between 

 iron pyrites — see pyrite 



joints — natural planes along which rock masses separate into more or less 

 regular blocks 



keeled — bearing a keel 

 kill — Dutch for creek 



lamellar — in the form of plates 



laniellibranchs — a class of mollusks with a bivalve shell, the valves being 

 right and left and each unsymmetric in itself — pelecypods, ex. clam, 

 mussel 



lamellose — platelike 



lateral — pertaining to the side 



lime mudrock — a rock composed of impalpable lime mud (example, litho- 

 graphic limestone) ; also called calcilutyte 



