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NEW YORK STATE MUSEUM 



goniatites — a group of cephalopod mollusks with a coiled shell in which 

 the margins of the septa or sutures are complicated by simple lobes 

 and saddles. It is not a natural group 



greywaeke — an old name for gray arenaceous and argillaceous rocks — not 

 much used 



grit — a silicious sandrock with coarse 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 spring 



hiatus — an unrepresented interval 



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



cypod shells 

 horizon — position 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 position of the 

 swimming organ or hyponome 



hypostoma — 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 water 



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 cliff, 



where they cut a gully which gradually becomes elongated 

 intercalation — insertion between 

 inter septal — occurring between the septa 

 interspaces — spaces between 

 iron pyrites — sec 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 



lamellibranchs — a Hass 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 calc;lutyte 



