(n.) An impure, massive, flintlike quartz or hornstone, of a dull color.
Example Sentences:
(1) Occurrence of well-preserved rod-shaped and coccoid bacteria in the Precambrian Gunflint chert (1.9 x 10(9) years old) has been demonstrated by electron microscopy.
(2) In order to evaluate the degree of morphological preservation of erythrocytes in bloodstains, an accidental human blood smear on white chert and several experimental bloodstains on hard substrates (the same stone-white chert; another type of stone-graywacke; a non-stone support-stainless steel), were stored in a room, in non-sterile and fluctuating conditions, for lengths of time ranging from 3 to 18 months.
(3) Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe).
(4) Two billion year old black chert lenses from the Duck Creek formation, northwestern Western Australia, contain abundant organically preserved microorganisms which are morphologically similar to fossils of approximately the same age from the Gunflint formation, Ontario.
Knap
Definition:
(n.) A protuberance; a swelling; a knob; a button; hence, rising ground; a summit. See Knob, and Knop.
(v. t.) To bite; to bite off; to break short.
(v. t.) To strike smartly; to rap; to snap.
(v. i.) To make a sound of snapping.
(n.) A sharp blow or slap.
Example Sentences:
(1) The pH-rate profile for inactivation of the RTEM-1 cysteine beta-lactamase by iodoacetate supports previous evidence [Knap & Pratt (1989) Proteins Struct.
(2) Photograph: Dixe Wills Size: 0.09sq miles Around 5,000 years ago, the community living at the Knap of Howar on Papa Westray crossed over to the Holm of Papay to build a burial cairn in which to lay their loved ones to rest.
(3) I thought this was all fair enough, although surely, I cavilled, if building simulacra of Neolithic houses and learning how to flint knap is our new route to the past, then really the actual monument itself is somewhat besides the point.
(4) On a hot day last week, workers from Poland and Bulgaria were spreading straw across fields of strawberries while the knapped flint of Hoo's several 13th-century churches shone in the sun.
(5) At the village of Knap o'Howar on Papay the bones of domesticated cattle, sheep and pigs have been found alongside those of wild deer, whales and seals, for example, while analysis of human bones from the period suggest that few people reached the age of 50.