14 10 264 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Amygdale</h2> Subject The topic of the resource <span>A vesicle (necessarily in an igneous rock), which has been filled in by a mineral crystallising from late-stage fluids. Amygdales are commonly produced by the crystallisation of <a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/57">quartz</a>, <a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/64">calcite</a> or zeolite.</span> Description An account of the resource <em>Have a look at the <strong>amygdaloidal basalt (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/11">L161</a>) </strong>in the 1A Reference Series.</em> Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Anhedral</h2> Subject The topic of the resource <span>A crystal displaying none of its characteristic crystal faces is called anhedral.</span> Description An account of the resource <em>Have a look at the <strong>granodiorite (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/8">L120</a>)</strong> for anhedral quartz, biotite and plagioclase.</em> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/eea0ce5b42c2fa513e4f5f9845e019fc.jpg cc4a42f011d53188d09b85125e3fe915 Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Anhydrite</h2> Description An account of the resource <div class="element"> <h3>Formula</h3> <div class="element-text"> <p>CaSO₄</p> </div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Non-silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>orthorhombic (+)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Colour in hand specimen:</span></em><span> white or colourless when pure</span><span> </span><br class="NoSpacing" /><em><span>Cleavage:</span></em><span> two at 90°</span><span> </span><br class="NoSpacing" /><em><span>Hardness:</span></em><span> 3-3.5</span></p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p class="NoSpacing"><em><span>Colour in plane polarised light:</span></em><span> colourless</span><span> </span><br class="NoSpacing" /><em><span>Pleochroism:</span></em><span> none</span><span> </span><br class="NoSpacing" /><em><span>Relief:</span></em><span> low</span><span> </span><br class="NoSpacing" /><em><span>Birefringence:</span></em><span> ~0.04; 3^rd order blue</span><span> </span><br class="NoSpacing" /><em><span>Extinction: </span></em><span>straight</span><span> </span><br class="NoSpacing" /><em><span>Twinning:</span></em><span> simple or repeated</span></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">anhydrite</div> </div> evaporite sulfur Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Anisotropic</h2> Subject The topic of the resource <div> <div class="element-set"> <div class="element"> <div class="element-text"> <p>The speed of light through any medium is inversely proportional to the refractive index of the medium. The refractive index of a mineral is determined by the arrangement and type of atoms within its structure.</p> <p>If the structure of the mineral allows light to travel at different velocities depending on the direction in which the light is passing through it, the mineral is anisotropic. That is to say, it has different refractive indices in different orientations.</p> </div> </div> </div> </div> Description An account of the resource <em>Compare with<span> </span><a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/213">isotropic</a>.</em> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/2b220318e8337f2ccddde4e3a52736b2.jpg c9f964a85e0bce7a4ae84d76bd8885d9 Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Apatite</h2> Description An account of the resource <div class="element"> <div class="element"> <h3>Formula</h3> <div class="element-text">Ca₅(PO₄)₃(OH,F,Cl)</div> </div> <div class="element"> <h3>Structure</h3> <div class="element-text"> <p>Non-silicate</p> </div> </div> <div class="element"> <h3>Crystal System</h3> <div class="element-text"> <p><em>Crystal system:</em><span> </span>hexagonal (-)</p> </div> </div> <div class="element"> <h3>Physical Properties</h3> <div class="element-text"> <p><em>Colour in hand specimen:</em><span> </span>green, white, yellow, blue brown etc.<br /><em>Hardness:</em><span> </span>5</p> </div> </div> <div class="element"> <h3>Optical Properties</h3> <div class="element-text"> <p><em>Colour in plane polarised light:</em><span> </span>generally colourless<br /><em>Pleochroism:</em><span> </span>weak to moderate in coloured varieties<br /><em>Relief:</em><span> </span>moderate<br /><em>Birefrinence:</em><span> </span>0.001-0.007; first order greys<br /><em>Extinction:</em><span> </span>straight<br /><em>Form:</em><span> </span>commonly hexagonal in cross-section</p> </div> </div> <div class="element"> <h3>Rock Specimens</h3> <div class="element-text"> <p><a href="/p1acollections/exhibits/show/igneous-rocks/l100">L100 Alkali granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l101">L101 Granite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l120">L120 Granodiorite</a><span> </span><br /><a href="/p1acollections/exhibits/show/igneous-rocks/l130">L130 Andesite, porphyritic (porphyrite)</a></p> </div> </div> <div class="element"> <h3>Mineral Name</h3> <div class="element-text">apatite</div> </div> </div> igneous volatile Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Aphanitic (or aphyric)</h2> Subject The topic of the resource <span>Igneous rocks made up of grains too small to be seen with the naked eye have an aphanitic texture. These rocks do not contain phenocrysts. They are non-porphyritic.</span> Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Argillaceous</h2> Subject The topic of the resource <p>Rocks comprising, or containing a significant proportion of, clay are described as argillaceous.</p> Description An account of the resource <div> <div class="element-set"> <div class="element"> <div class="element-text"> <p><em>Have a look at the<strong> argillaceous limestone (<a href="https://wserv3.esc.cam.ac.uk/p1acollections/items/show/29">L350</a>)</strong> in the 1A Reference Series.</em></p> </div> </div> </div> </div> <div> <div class="element"> <div class="element-text"></div> <div class="collection"></div> </div> </div> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6009607451cd8aaf8df0774b2bdfdcde.png 8b21689fe4d996882b7eb68bf7e6ebbf Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Fossils Description An account of the resource <p>Welcome to the fossils section of the website. This is designed to help you learn the different characteristics of each major fossil group so that you are able to distinguish between them.</p> <p>First year students, please refer to the specimens housed in the first year teaching laboratory. There is no substitute for handling the specimens themselves; this website is just an accessory to help you along the way.</p> <p>Animals occupy different environments, have different life habits and lived through different periods in geological time. It is good to be aware of these differences in lifestyle and timing, within and between phyla, classes, orders and families.</p> Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Belemnite</h2> Description An account of the resource <div> <div class="element-set"> <div class="element"> <div class="element-text"> <h2>Taxonomy<span><br /></span></h2> <p>Phylum: Mollusca</p> <p>Class: Cephalopoda</p> <p>Subclass: Coleoidea</p> <p>Cohort: Belemnoidea</p> <h2>Diagnostic Features</h2> <p>Diagram with labelled features of belemnites</p> <p>'Bullet' shape</p> <p>Phragmocone: chambers divided by aragonitic septa (often preserved as conical cavity)</p> <p>Radial calcite crystals form the guard</p> <h2>Way of life</h2> <p>Nektonic</p> <p>Predatory</p> <p>Marine</p> <h2>Advanced notes</h2> <p>Exceptional preservation of belemnites showing soft parts has shown them to be very similar to squid in shape. The guard and phragmocone were held inside the soft parts of the animals, acting as a kind of backbone.</p> <p>Because the phragmocone is made of aragonite it is often not preserved. In contrast the calcitic guard is very often preserved. This means that a common preservation of belemnites is of the guard with a conical hole where the phragmocone once was. This empty conical chamber is often crushed.</p> <h2>Specimens</h2> <p><a href="/p1acollections/exhibits/show/belemnites" target="_blank" rel="noreferrer noopener">Browse belemnites</a></p> <h2>External Links</h2> <p><a href="http://www.conchsoc.org/MolluscWorld20/7">Mollusc World</a></p> <p><a href="https://www.digitalatlasofancientlife.org/learn/nature-fossil-record/types-of-fossil-preservation/">Learn about types of preservation</a></p> </div> </div> </div> </div> Cretaceous Jurassic Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Description An account of the resource This glossary describes a number of geological terms with which the 1A students should become familiar.<span> It is by no means an exhaustive list, but is aimed to help you understand the material within the first year course.</span> Title A name given to the resource Glossary Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Birefringence</h2> Subject The topic of the resource <p>Light passing through a mineral is resolved into two permitted vibration directions. In an anisotropic mineral light travels at different velocities along the two vibration directions. The ray travelling in the slow vibration direction will be retarded compared with the ray travelling in the fast vibration direction. On leaving the mineral grain the two rays will interfere, producing interference colours.</p> <p>When the slow ray exits the mineral grain the fast ray will already have exited the grain and travelled an additional distance know as the optical path difference, or retardation (Δ). This distance is proportional to the thickness of the mineral grain (t) and the difference in the refractive indices of the two vibration directions (n₁-n₂):</p> <p>Δ = t(n₁-n₂)</p> <p>The birefringence is the difference in the refractive indices of the two vibration directions (n₁-n₂).</p> <p>When rotated under cross-polarised light anisotropic minerals display changing interference colours called birefringencecolours. The birefringence (n₁-n₂) of the mineral can be determined from these colours using a Michel-Levy chart.</p> https://wserv3.esc.cam.ac.uk/p1acollections/files/original/d49f8d0b84aff13f791c8c2420fedf4e.png 4d57e7693623c7a0e67dc29de449d2e6 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f3bb76afa6e54d47fead956e0ec0de31.png 9b36b6b0f67a6ac5d63ae84f7fa5d566 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Fossils Description An account of the resource <p>Welcome to the fossils section of the website. This is designed to help you learn the different characteristics of each major fossil group so that you are able to distinguish between them.</p> <p>First year students, please refer to the specimens housed in the first year teaching laboratory. There is no substitute for handling the specimens themselves; this website is just an accessory to help you along the way.</p> <p>Animals occupy different environments, have different life habits and lived through different periods in geological time. It is good to be aware of these differences in lifestyle and timing, within and between phyla, classes, orders and families.</p> Physical Object An inanimate, three-dimensional object or substance. Note that digital representations of, or surrogates for, these objects should use Moving Image, Still Image, Text or one of the other types. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource <h2>Bivalve</h2> Description An account of the resource <h2>Taxonomy</h2> <p>Phylum: Mollusca</p> <p>Class: Bivalvia</p> <h2>Diagnostic features</h2> <p>Palial line/palial sinus</p> <p>Adductor muscle scars</p> <p>Growth lines</p> <p>Dorsoventral symmetry (some exceptions, for example<span> </span><em>Gryphaea</em>)</p> <p>Two hinged valves</p> <p>Umbo</p> <p>Hinge</p> <p>Gills (rarely preserved)</p> <h2>Stratigraphic range</h2> <p>Cambrian to present</p> <h2>Way of life</h2> <p>Bivalves have occupied many environmental niches, living in a variety of ways:</p> <p>Epifaunal, infaunal, nektonic</p> <p>Marine, freshwater, brackish</p> <p>Filter feeders through gills</p> <p>Majority of bivalves begin life in a planktonic larval stage</p> <p>By looking at the shell shape and palial sinus of fossil bivalves it is possible to say something about its mode of life.</p> <h2>Advanced notes</h2> <p>Apparent increase in bivalve diversity over time (or is this just a preservational bias?)</p> <p>Bivalves makes their shells out of calite, aragonites, or both</p> <p>The adductor muscles are used to keep the shell of the bivalve closed. This means that when they are relaxed, the ligament between the valves pulls them apart, so the 'relaxed state' for bivalves is 'open'.</p> <p>The depth at which infaunal bivalves burrowed can be inferred from the palial sinus. The more prominent the palial sinus, the deeper the bivalve burrowed. This is because the size of the palial sinus is indicative of the size of siphon needed, which in turn depends on the depth of the burrow (deeper burrow, larger siphon).</p> <h2>Specimens</h2> <p><a href="/p1acollections/exhibits/show/bivalves" target="_blank" rel="noreferrer noopener">Browse bivalves</a></p> <h2>Links</h2> <p><a href="https://www.youtube.com/watch?v=H5O1XYZcDh8" target="_blank" rel="noreferrer noopener">youtube</a>: scallops swimming</p> <p><a href="http://www.museum.zoo.cam.ac.uk/bivalve.molluscs/lifestyles.of.bivalve.molluscs/">Cambridge University Museum of Zoology</a>: Lifestyles of bivalves</p> <p><a href="http://peabody.yale.edu/collections/blog/2011-11-07/brachiopods-versus-bivalves" target="_blank" rel="noreferrer noopener">Yale Peabody Museum of Natural History</a>: differences between bivalves and brachiopods</p> <p><a href="https://www.digitalatlasofancientlife.org/learn/nature-fossil-record/types-of-fossil-preservation/">Learn about types of preservation</a></p> <h2>Also</h2> <p>Go to the front of the 1A Lab. A display on the right hand side (by the window) shows a number of bivalves in life position. Have a look at how they have adapted their shape and other features to their way of life.</p> shell symmetry