25 10 264 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/6632e388363a536b4fa89fbce0b5a699.jpg f359ae54e000492b36d10dc27878446c https://wserv3.esc.cam.ac.uk/p1acollections/files/original/9901453206757825164066c3b5133da2.jpg a71e28f533edde80e8a18407318711f5 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/604a1c135c80a190d334065f23bba33a.jpg c6f41a542eca91cc17ca64984969872f 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><strong>L331<br /></strong></h2> <h2>Sandstone, wacke</h2> Subject The topic of the resource <h3>Specimen Age</h3> <div class="element-text">Silurian<br /><h3>Location</h3> <div class="element-text">Austwick Grit<br />Austwick, Yorkshire</div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text">Dark grey rock, mainly fine sand.<br />Does not react with acid, probably mainly quartz.<span> </span><br />Some glints of mica.<span> </span><br />Cement reacts with acid, so it is at least partially carbonate.<span> </span><br />Band of brown-grey material is due to weathering.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text">The thin-sections are only cut from dark grey, unweathered region of the rock. They are best viewed under high magnification.<br /><br />Sub-angular to sub-rounded quartz grains. Mainly fine sand, with a significant proportion of silt. &gt;15% clay, so this is a wacke.<br />A few white mica flakes and opaque grains.<br />The main cement is carbonate, though the grains are also partially cemented by the clay grade grains.</div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Wackes are commonly produced by<span> </span><a href="/p1acollections/items/show/261">turbidity currents</a>, though we cannot be sure without seeing graded bedding.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">sandstone<br />wacke</div> </div> </div> turbidity current https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4d660cc7e88f1a09293f8f1cfb0141a4.jpg e3d1332f28dfb74246d9c020be38afe8 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/275bfe6e51cf0c00750113931bfde0a2.jpg 3181f15a157a6e130504affccf31e37f https://wserv3.esc.cam.ac.uk/p1acollections/files/original/209c57cf6df9a68b526bd1b50071f5ed.jpg 35569654b213a0c11e326d470c29a08d 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><strong>L327<br /></strong></h2> <h2>Sandstone, ferruginous</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text"> <p>Cretaceous</p> <h3>Location</h3> <div class="element-text"> <p>Carston, Lower Greensand<br />Hunstanton</p> </div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Mainly medium sand (to coarse sand in the case of L327a).<span> </span><br />Yellow-brown<span> </span><span>iron stained</span><span> </span>quartz, cemented by the same yellow brown oxide. A few larger quartz grains up to 5 mm long. Grains are angular to sub-rounded, and poorly sorted.<span> </span><br />Fizzing with acid, indicating that there is a carbonate cement.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Angular to sub-angular grains of quartz, displaying<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>.<span> </span><br />Most have thin brown rims of iron oxide.<span> </span><br />A few grains of feldspar.<span> </span><br />Minor carbonate cement (sparite).</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Deposited in an aqueous environment, since it is not clean enough to be<span> </span><a href="/p1acollections/items/show/167">aeolian</a>.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p><span>Iron staining</span><span> </span><br />Hematite (Fe₂O₃) → red (blood-red, cherry-red, brown-red) iron-staining<span> </span><br />Limonite (FeO(OH)•nH₂O) → yellow or brown iron-staining</p> <p>The yellow colour of this rock is probably produced by limonite.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">ferruginous sandstone</div> </div> </div> aqueous sorting https://wserv3.esc.cam.ac.uk/p1acollections/files/original/ccd2e73c233ad6349b5c93414d58b231.jpg 62525c1eed532ca964421366771e92aa https://wserv3.esc.cam.ac.uk/p1acollections/files/original/2d5710f094a41112efe4a6ced6ef87ba.jpg 1c4dff891bd163644992404cd5efe88c https://wserv3.esc.cam.ac.uk/p1acollections/files/original/16246ed0fde11e3e222ba6d720f0af18.jpg 2a9a504b49d86b21cd7f29ccbce43c7d 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><strong>L326<br /></strong></h2> <h2>Sandstone, ferruginous arenite</h2> Subject The topic of the resource <h3>Specimen Age</h3> <div class="element-text">Permian<br /><h3>Location</h3> <div class="element-text">Penrith Sandstone<br />Appleby, Westmorland</div> </div> Description An account of the resource <div class="element"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text">Reddish brown rock. Medium sand grade.<br />Round to sub-round grains of quartz, often with a thin rim of red hematite. Mainly reddish and pink-brown grains, fewer white grains and very few black grains. Well sorted and well cemented.<br />No fizzing with acid, so does not contain significant carbonate.<span> </span><br /><br />Laminations can be observed in sample L326b. There is an inter-layering of coarser and finer laminae.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Fine laminations can be seen when the thin-section is held up to the light.<span> </span><br />Moderately well rounded quartz grains with thin rims of hematite, and overgrowths of quartz in optical continuity with the original grain.<span> </span><br />Occasional grains of very fine quartzite, microcline, plagioclase, mica and decomposed fine-grained igneous rocks.<span> </span><br />Siliceous cement and the secondary quartz<span> </span><a href="/p1acollections/items/show/232">overgrowths</a><span> </span>hold this rock together.</p> <p>The grains are finer as a whole in L326b, and less well rounded.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Probably deposited in an<span> </span><a href="/p1acollections/items/show/167">aeolian</a><span> </span>environment, since it almost entirely comprises well sorted and well rounded quartz grains.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">ferruginous sandstone<br />ferruginous arenite</div> </div> </div> aeolian lamination sorting https://wserv3.esc.cam.ac.uk/p1acollections/files/original/00f841abc429436b12138c68e9e1d2de.jpg 7a9247d7745cda074637c5b09e12aa1f https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f88c1bb129d373b147642f8efdbe0b01.jpg 6a29f5dce510fba60873bf7f5c362052 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/4c5c6e868e4ecb7a96c6dbacd3fe9d99.jpg 188fa31e087acc0ba82ee2bfd560f8fa 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><strong>L325<br /></strong></h2> <h2>Sandstone, calcareous cement</h2> Subject The topic of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Age</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Jurassic<br /><br /><div class="element-set"> <div class="element"> <h3>Location</h3> <div class="element-text">Portland Group, Shotover Hill, Oxford</div> </div> </div> </div> </div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Hand Specimen</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Pale grey rock, mainly medium to coarse grained quartz sand. Poorly sorted.<span> </span><br />Small amounts of lithic fragments up to 10 mm across, and shell fragments.<span> </span><br />Contains &lt;15 vol% clay, making it an arenite.<br />Pale grey cement fizzes with acid, indicating that it is carbonate.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Quartz grains, sub-angular to sub-rounded, occasionally rounded, displaying<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>.<span> </span><br />Lithic fragments including flint and quartzite.<span> </span><br />Some grains of feldspar.<span> </span><br />Rare small<span> </span><span>green clasts</span>.<span> </span><br />Grain supported.<span> </span><br />Cemented by a sparry calcite cement. The cement crystals are large, each enclosing a number of sedimentary grains.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>Deposited in an aqueous environment; grains are not rounded enough to have been deposited in an<span> </span><a href="/p1acollections/items/show/167">aeolian</a><span> </span>environment.</p> </div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p>The rare<span> </span><span>green clasts</span><span> </span>are made up of a<span> </span><a href="/p1acollections/items/show/184">cryptocrystalline</a><span> </span>material, which may be a type of amphibole called glauconite, and some rather decomposed rhyolite or andesite.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">Calcareous sandstone<br />Calcareous arenite</div> </div> </div> </div> </div> </div> aqueous sorting https://wserv3.esc.cam.ac.uk/p1acollections/files/original/32a05eeb9aabaf5fb28349a082d5c394.jpg 02b0bedfd37de54daaf46474c660f569 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/65b615211cc1922e57de5ae5e048795e.jpg 84867e2d04166abe4cf5d4729cbc41dc https://wserv3.esc.cam.ac.uk/p1acollections/files/original/c8be6e16095920cbfd64b604e493e1a4.jpg e1bbccc19d642b02fb9155ebe414a979 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><strong>L324<br /></strong></h2> <h2>Sandstone, feldspathic arenite</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text">Precambrian<br /><h3>Location</h3> <div class="element-text">Torridonian Group, North West Scotland</div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Hand Specimen</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Reddish brown rock made up of pinkish feldspar, colourless quartz, and some dark grey grains. Medium to coarse sand. Moderately rounded. Fairly well sorted.<span> </span><br />Contains &lt;15 vol% clay, so this is an arenite.<span> </span><br />No fizzing with acid, so does not contain significant carbonate.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Quartz (~65%)<span> </span><br />- Includes fresh quartz grains with<span> </span><a href="/p1acollections/items/show/263">undulose extinction</a>, quartzite grains with internal<span> </span><a href="/p1acollections/items/show/257">sutures</a>, and quartz vein material. Some quartz grains have opaque rims.</p> <p>Feldspar (~35%)<span> </span><br />- Mainly microcline, some plagioclase. Some<span> </span><a href="/p1acollections/items/show/228">microperthite texture</a><span> </span>and decomposition to clays.</p> <p>All grains are moderately rounded and fairly well sorted. The rock is well compacted. A thin film of cement mainly hematite and clay coats the grains.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>This rock contains too much feldspar, and the grains are not sufficiently well rounded nor well sorted to have been deposited in an<span> </span><a href="/p1acollections/items/show/167">aeolian</a><span> </span>environment. The sediments were deposited in an aqueous environment.<br /><br /><br /></p> </div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text"> <p>sandstone<br />feldspathic arenite</p> </div> </div> </div> </div> </div> </div> aqueous compacted sorting https://wserv3.esc.cam.ac.uk/p1acollections/files/original/de416cb250390ced9266b0dc46e032ab.jpg e6c675e8595cdeae101d2c42a98541da https://wserv3.esc.cam.ac.uk/p1acollections/files/original/3de35d39290e782696bc440ea5d5882c.jpg d61148549d7e0e0ec79e4fdf95957213 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/941313bb34f96b29318b1045b7884989.jpg 6a0f1becf00fa29aed87ddf02b468b15 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><strong>L323<br /></strong></h2> <h2>Sandstone, arenite</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text">Jurassic<br /><br /><h3>Location</h3> <div class="element-text">Estuarine Series, North Yorkshire</div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Hand Specimen</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text">Pale yellow grey rock, almost entirely made up of medium sand quartz grains. These are sub-rounded, very well sorted, and are held together by a matrix of siliceous silt. Contains a significant amount of clay, but &lt;15 vol%, so it is an arenite.<span> </span><br />No fizzing with acid, so does not contain significant carbonate.<span> </span><br />Weakly laminated.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text">Sub-round grains of quartz, some opaque grains and a few flakes of white mica.<span> </span><br />Siliceous, silty matrix.</div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text"> <p>This rock was deposited in a moderate energy, aqueous environment. The grains are not well rounded enough to be<span> </span><a href="/p1acollections/items/show/167">aeolian</a><span> </span>sediments.</p> </div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text"> <p>sandstone<br />arenite</p> </div> </div> </div> aqueous sorting https://wserv3.esc.cam.ac.uk/p1acollections/files/original/9c74043dd4765743a7af9b90b0f50ef4.jpg ac96894746f8137ce25d5f1f809dfa00 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/afce700bce529e295af89d899592b41e.jpg ef8d9d97da68dd0afcc64131b171809e https://wserv3.esc.cam.ac.uk/p1acollections/files/original/0e48212f1384b76ca45fc688ba4e0b6d.jpg 0efd2cfb2ca972cc8e8ebbb0583ac682 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><strong>L311<br /></strong></h2> <h2>Conglomerate</h2> Subject The topic of the resource <h3>Age</h3> <div class="element-text">Eocene<br /><h3>Location</h3> <div class="element-text">Hertfordshire</div> </div> Description An account of the resource <div class="element-set"> <div class="element"></div> </div> <div class="element-set"> <div class="element"> <h3>Hand Specimen</h3> <div class="element-text">Poorly sorted. Rounded clasts up to ~15 mm long.<span> </span><br />Pale yellow matrix of quartz grains.<span> </span><br />Cement fizzes with acid, indicating that it contains carbonate.<span> </span><br />This conglomerate is just clast-supported.</div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Rounded clasts of very dark red brown<span> </span><a href="/p1acollections/items/show/171">amorphous</a><span> </span>silica (chert) and<span> </span><a href="/p1acollections/items/show/242">polycrystalline</a> quartz.</p> <p>Matrix of quartz grains (typically 0.25 mm) and fine-grained carbonate cement (sparite). Dark red-brown<span> </span><span>iron staining</span>.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text">Deposited in a high energy environment.</div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p><span>Iron staining</span><span> </span><br />Hematite (Fe₂O₃) → red (blood-red, cherry-red, brown-red) iron-staining<span> </span><br />Limonite (FeO(OH)•nH₂O) → yellow or brown iron-staining</p> <p>The red-brown colour of this rock is probably produced by hematite.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">conglomerate</div> </div> </div> clast supported high energy https://wserv3.esc.cam.ac.uk/p1acollections/files/original/00db217bd8288150c439f1ca37a8cfec.jpg 20ab67c34086aeea11bab20c8a79886e https://wserv3.esc.cam.ac.uk/p1acollections/files/original/dec6f2245ea893d30d732fad22681274.jpg 2c9eeea810ad45f5041e688c15f68300 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/df792c1dff764855c0f5a8bca4f4832b.jpg ea4c3e9e50b4e890ff1f6c1f86466fdb 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><strong>L310<br /></strong></h2> <h2>Breccia</h2> Subject The topic of the resource <h3>Specimen Age</h3> <div class="element-text"> <p>Permian</p> <h3>Location</h3> <div class="element-text"> <p>Brockram, Cumbria</p> </div> </div> Description An account of the resource <div class="element-set"> <div class="element"> <div class="element-text"> <h3>Hand Specimen</h3> </div> </div> </div> <div class="element-set"> <div class="element"> <div class="element-text"> <p>Very poorly sorted.Angular to sub-angular clasts up to 30 mm long. Randomly orientated.<span> </span><br />Clasts mainly pale grey, some white, some red.<span> </span><br />Red-brown colour of the fine-grained matrix indicates<span> </span><span>iron staining</span>.<span> </span><br />Matrix and some clasts fizz with acid, indicating that they are made of carbonate. This is a limestone.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text">Variety of clasts: sedimentary rock fragments, carbonate and feldspar crystals, fine-grained quartz and carbonate, some bioclasts. Clasts are quite angular.<br />Matrix of very fine-grained clays containing fragments of quartz and carbonate.</div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text">Clast-supported. Clasts are angular, so sediments cannot have been transported far. (NB, if this rock were matrix supported the clasts could have been transported a long way without losing their angularity.)<span> </span><br />Probably scree accumulation during desert conditions, from approximately the same horizon as L326.</div> </div> <div class="element"> <h3>Advanced Notes</h3> <div class="element-text"> <p><span>Iron-staining</span><span> </span><br />Hematite (Fe₂O₃) → red (blood-red, cherry-red, brown-red) iron-staining<span> </span><br />Limonite (FeO(OH)•nH₂O) → yellow or brown iron-staining</p> <p>The red-brown colour of this rock is probably produced by hematite.</p> </div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">breccia</div> </div> </div> clastic scree 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><strong>L300<br /></strong></h2> <h2>Granulometer</h2> Description An account of the resource <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Six vials containing unlithified terrigenous sediments of different grain sizes. These are:</p> <table><tbody><tr><td> </td> <td>grain size (mm)</td> <td>grain size (phi)</td> </tr><tr><td>Very coarse sand</td> <td>1-2</td> <td>-1-0</td> </tr><tr><td>Coarse sand</td> <td>0.5-1</td> <td>0-1</td> </tr><tr><td>Medium sand</td> <td>0.25-0.5</td> <td>1-2</td> </tr><tr><td>Fine sand</td> <td>0.125-0.25</td> <td>2-3</td> </tr><tr><td>Very fine sand</td> <td>0.063-0.125</td> <td>3-4</td> </tr><tr><td>Mud</td> <td>&lt;0.063</td> <td>&gt;4</td> </tr></tbody></table></div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text">These are not sections cut from a rock. They are cut from a block of resin containing sedimentary grains. Use these sections to familiarise yourself with grain sizes, as seen in thin-section.</div> </div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">granulometer</div> </div> Grain size https://wserv3.esc.cam.ac.uk/p1acollections/files/original/ccf4a152eba569461bf6ef055f4b1967.jpg 09fce135a7daa260d1040c49fa782944 https://wserv3.esc.cam.ac.uk/p1acollections/files/original/f138a19e1e584077538e0a5fb26e22db.jpg 01aab9478722295690d2c9ca02f53a9b https://wserv3.esc.cam.ac.uk/p1acollections/files/original/8bb0c75035b89eb9fa8462899036cdf4.jpg 4ac94845dc4d2450665869ea8855f2ea 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><strong>L201<br /></strong></h2> <h2>Tuff</h2> Description An account of the resource <div class="element"> <h3>Hand Specimen</h3> <div class="element-text"> <p>Fine-grained, blue-green, sedimentary texture.<span> </span><br />Slaty<span> </span><a href="/p1acollections/items/show/180">cleavage</a>.<span> </span><br />Some patches of lighter and finer-grained material.</p> </div> </div> <div class="element"> <h3>Thin-section</h3> <div class="element-text"> <p>Slaty cleavage due to the alignment of chlorite and muscovite.<span> </span><br />Cross-cut by the blobs of the fine-grained material. These are orange-brown in thin-section. Could be water-lain ash, ripped-up to form clasts.<span> </span><br />Very fine-grained, brown matrix, probably<span> </span><a href="/p1acollections/items/show/266">volcanic</a><span> </span>ash.<span> </span><br />Carbonate, quartz and opaque clasts slightly larger than the matrix.</p> </div> </div> <div class="element"> <h3>Rock History</h3> <div class="element-text">Fine-grained volcanic ash deposited by an explosive volcanic eruption has undergone low grade metamorphism to produce a slaty cleavage.</div> </div> <div class="element"></div> <div class="element"></div> <div class="element"> <h3>Rock Name</h3> <div class="element-text">tuff</div> </div> cleavage metamorphism slaty