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-TO = IN S'J2077, PAN Lj II. by Trouper.
+=====Story In Stone - Part 2.=====
-Part I (January edition) of the ancient history of the Shoalhaven 1-Z. area outlined the way in which the various rocl,:s are fora shale and sandstone are food as sedionts
-on the floor of a lake or sea, and changed into flint or slate
+by Trouper.
-when the countryside is crisJ olded by r;reat forces in the earth's crust; whilst li..estone is an acculation of the alciicontaining reains of living organisins, e g. corals.
-Now that we understand the nature of the rocks -- the brown and grey flint and slate in the lower part, and the sandstones overl:s7ini- the:_, 70 can =a lno the history of the area from a map -- a geologic map (Plato I). In the eastern portions of this -zap, we sec that t:.ice are Ordovician slates, overlain b:; a cap of Permian sandstone, as is seen in the section, A-A. The na_es need cause no alarm -- they are simply a convenient wa-3, of classifying a rock accordi,L to its ag;e. Thus, fro-_, the list on the :map, ''Ordovician'' roc::s Fore first laid down as sedi-,ents during the period, 400 :Mien to 380 million years ago;"Silurianrocl:s originated during the Period 380 :1Mo:a to 320 million years ago, and so on.
+Part 1 (January edition) of the ancient history of the Shoalhaven R. area outlined the way in which the various rocks are formed - shale and sandstone are formed as sediments on the floor of a lake or sea, and changed into flint or slate when the countryside is crushed and folded by great forces in the earth's crust; whilst limestone is an accumulation of the calcium-containing remains of living organisins, e.g. corals.
-ow what evidence do we base these state_ents of age? ike chief evidence is that of fossils. In the sea which overlay the area of the ordovicia:o slates were small fish called graptolites, organisms which lived in colonies, and grow in sall, stringy clusters so that the a.?greRate was somewhat as illustrated in Plato II. wow, these graDtolites underwent a fairly rapid evolutionarz- -process -- the number of branches and the direction of growth of those branches changed, as is ill'ustl'at:;d by reading the figure from left to right. Hence, if a particular t:oo of ,?;raptolito is found in a particular strati of slate, then its evolutionary stage at once gives a 1,:e:y to the age of that slate.
-Now, ),hen we loo:: to either side of the gorge in this area, we note three ihings 1,'irstl, the lower roch strata is disto,-2tcd, and atabout 1,000 feet above the river gives way
+Now that we understand the nature of the rocks - the brown and grey flint and slate in the lower part, and the sandstones overlying them, we can examine the history of the area from a map - a geologic map (Plate 1). In the eastern portions of this map, we see that there are Ordovician slates, overlain by a cap of Permian sandstone, as is seen in the section, A-A. The names need cause no alarm - they are simply a convenient way of classifying a rock according to its age. Thus, from the list on the map, "Ordovician" rocks were first laid down as sediments during the period, 400 million to 380 million years ago; "Silurian" rocks originated during the Period 380 million to 320 million years ago, and so on.
-sudd enly to hexdzolitally heddel rocks that is, the upper
-rocks were not in e:dstence at the ti- then the area was subjected to the great earth forces which distorted the lower shales, and hardened tlIaa to slates. Secondly, the lower are brown or gr(* slates, laid de= far :ro the shore of a sea; the upper arc yellow sandstones which are claposited near a sea or lake shore. Thirdly, referring to the ages lizted on the map, the Ordovician ago ended 380 million years ago, but the Pc.,,r_dan did not begin until 155 million years latur. Layer by lair the shalQs wore built up, year by year -- and
+Upon what evidence do we base these statements of age? The chief evidence is that of fossils. In the sea which overlay the area of the ordovician slates were small fish called graptolites, organisms which lived in colonies, and grew in small, stringy clusters so that the aggregate was somewhat as illustrated in Plate 2. Now, these graptolites underwent a fairly rapid evolutionary process - the number of branches and the direction of growth of those branches changed, as is illustrated by reading the figure from left to right. Hence, if a particular type of graptolite is found in a particular stratum of slate, then its evolutionary stage at once gives a key to the age of that slate.
-tha-0- a ZAP- Aiat o 155 1J toz. fo;p, the
-c5eCi
+Now, when we look to either side of the gorge in this area, we note three things. Firsty, the lower rock strata is distorted, and at about 1,000 feet above the river gives way suddenly to horizontally beddee rocks - that is, the upper rocks were not in existence at the time when the area was subjected to the great earth forces which distorted the lower shales, and hardened them to slates. Secondly, the lower rocks are brown or grey slates, laid down far from the shore of a sea; the upper are yellow sandstones which are deposited near a sea or lake shore. Thirdly, referring to the ages listed on the map, the Ordovician age ended 380 million years ago, but the Permian did not begin until 155 million years later. Layer by layer, the shales were built up, year by year - and then a gap. A hiatus of 155 million years, for the Silurian, Devonian and Carboniferous ages are missed out. Deposition ceased, and in the interim the shales were crushed and folded and hardened into slates; and then, so many million years later, when the crushing foces had died away, sedimentation occurred again.
-tlAr ; 2orwri-
-$34141-6,1,1 e.
+What is the explanation of this missing chapter? It lies in the fact that, throughout the Silurian, Devonian and Carboniferous ages, all this land had been uplifted above the water level; the sea had drained away, and where previously, deposition had been occurring, denudation (erosion) was now taking place. And finally, the area had been submerged once more, but this time the sea had not extended very far beyond the regions we are examining, and sandstones were laid down where for ages only erosion and earth-crumpling had taken place.
-Poi ai,e0f
-NO, 00)000 ru 260,000,000 , le4rS
+Now look to Bungonia - here, Silurian shales and limestones. The rocks of the missing chapter! This area had been submerged whilst the eastern sector had been uplifted. That is, a shore-line had existed between the area now called Bungonia, and the opposite side of the present Shoalhaven. A noteworthy feature of this limestone belt is the fact that the remains of the ancient corals flank a gorge 1,000 feet deep. And yet, coral is a shallow-water organism and does not build at depths greater than about 10 feet. How, then, can there be 1,000 feet of fossil remains where the water had not been more than some 10 feet deep? The fact is that the land had not tilted and lain still, but it had gone on gradually tilting for millions of years, and as the region sank, fraction by fractions the corals went on building, always growing upwards to maintain their normal depth below the rising water.
-Devoy-N( --
-, 0,--3200c001000 yeA,-,5 ago
+However, despite the existence of Silurian sediments on the Bungonia sides there is evidence even here that the progression was not a smooth one. For the upper slates were somewhat eroded away before being covered by the later shales. That is a general uplift had raised the whole land above the sea, and then re-submerged the western side. It did not now subside beneath the original sea, however, being covered instead by a vast inland lake.
-S ---
-,tO,o0ooO0,
+This land being now submerged, and gradually tilting to allow of the building of the corals, erosion started on the still-uplifted eastern section. Year by year, rivers were breaking down the Ordovician slates, and carrying the particles westward - to the lake, this time, and not to the sea - where they were deposited as muds around the corals, later to be dried to form the Silurian shales we now see around the limestone roof.
-Oreicylc; air\
--- ao,co 0
+We now have the history before us, and may recapitulate the tale, in some six stages: see Plate 2.
-Sec-fl or\ B-B
-t-tv1,41PoINI!"
+__Stage 1__. Ordovician times. Whole area the floor of a sea, far from shore; muds being deposited year by year in horizontal layers on the sea-floor - later dried to form shales. Graptolites in sea and on muds.
-c.) havQ" et
-"40=
+__Stage 2__. Silurian times. Whole area uplifted and partly eroded (time-gap between Ordovician and Silurian at Bungonia). Intense earth forces crush and fold area into slates.
-\
-=Iry
+__Stage 3__. Silurian. West side subsides under inland lake, with shoreline east of Bungonia Gorge: limestone belts established and Ordovician rocks of east carried west by rivers; re-deposited in lake.
-IF
-N ./e./
+__Stage 4__. Devonian - Carboniferous times. Region uplifted entirely. Erosion of Ordovician slates and of more recent Silurians of west.
-z
-i3u BoirNia 1,3airbees ck
+__Stage 5__. Permian times. Eastern sector submerged below sea, but not so far from shore as in stage 1 (shoreline close to present Barber's Creek). Sandstones deposited in horizontal layers.
-Devonian and Carboniferous ages are :Lissed out. Doposon
-CCCCar:a tc; ':73ro cruso folcloCi
+__Stage 6__. Post-Permian times. Bodily uplift of whole area, and erosion to present contours.
--1.araenea into slates; aTa then, so illior :Tears later, Then the crushin foces haC_ died away, sedimentation occurred again.
-What is the explanation of this missing chapter? It lies in the fact thats throughout the Silurian, Devonian and Carboniferous ages, all this land had been uplifted above the water level; the sea had drained away, and where previously, deposition had been occurring, denudation (erosion) was now taking place. And finally, the area had been submerged once more, but this time the sea had not extended very far beyond the regions we are examining, and sandstones were laid down where for ages only erosion and earth-crumpling had taken place.
+The story is there complete in the main, and only one minor aspect remains. During the Silurian activity, molten rock from deep down in the earth's crust welled up into the areas near the present Maru1an. This, on cooling gave rise to granite and porphyry in these regions.
-Now look to Bungonia -- here, Silurian shales and litones. The rocks of the missing chapter: This area had been subil3e rged whilst the eastern sector had been uplifted.
-' That is, a shore-line had existed between the area now called Bungonia, and the opposite side of the present Shoalhaven. A noteworthy feature of this limestone belt is the fact that the remains of the ancient corals flank a gorge 1,000 feet deep. And yet, coral is a shallow-water organism and does not build at depths greater than about 10 feet. How, then, can there be 1,000 feet of fossil remains where the water had not been more than some 10 feet deep? The fact is that the land had
+Thus we may see in the story of the ancient Shoalhaven area, not a tale of hills eternal and timeless lands, but of a varied inter-change of land and sea. On future walks, you may see yourself the story revealed; the folded slates of the lower gorge, the sandstones of the upper, and the limestones of Bungonia - pieces of a history before the dawn of man.
-not tilted and lain stills but it had gone on gradually tilting for millions of years, and as the region sank, fraction by fractions the corals went on building, always growing upwards to maintain their normal depth below the rising water.
-However, despite the existence of Silurian sedizents on the Bungonia sides there is evidence even here that the progression was not a smooth one. For the upper slates were somewhat eroded away before being covered by the later shales. That is a general uplift had raised the whole land above the sea, and then re-submerged the western side. It did not now subside beneath the original sea, however, being cove-red instead - by a vast inland lake.
+----
-This land being now submerged, and gradually tilting to allow of the building of the corals, erosion started on the
-- still-uplifted eastern section. Year by year, rivers were break-
-ing down the Ordovician slates, and carrying the particles westward -- to the lake, this time, and not to the sea -- where they were re-posited as muds around the corals, later to be
-_dried to form the Bilur:Lansales e aclJw ,%az around the lime-
-stone roof.
--,SiAGES OFZIEVFLOPMENT
-=.27- Oa-hi/in/co fro-,
-Whole arei; ur)cVer ep-confineria
-Cirapieldes Jv /r1 se.)
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-S,Its Cein9 deposited later -to ic;rol 5 b-,,Ce
-I r
-Mud', e5n Cited 01 Q
-Si-a elf- Silurtat7
-Whole area hifeci 6t9tie. 5e,4 ievei
-M UD5 Rivedrired zwav
-dried io form SHA1E5 ton-woo-ice EROSION
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--1,3reat Fones Crush hrea
-Deposi-tion occurs agz;.:(1,-
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-//11170/6. por/i or? / f/ o<
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-v4.11% up wail?, cruc
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-Wkoler er a subject foerosiori &ibIded slates worn dowe%Fo pi1-1
--\4
-Ste e7- Permian eas7L6,,,-r/ Secr'or
-uhrorgeof oncle-,r grest). t /oke
-.1.1111141.#.1141,..0.11140.4.4110.4.1.110,4.0.414111,04errm,
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-_Deposition of
-SrD, st ones
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-(APProx Life cize)
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--.Te now have the history before us, and :Jay recapitulate the tale, in some six stages: see Plate 2.
-.11221:2_1, Ordovician tiz-es. Mole area the floor of a sea, far frou shore; muds being deposited year by year in horizontal layers on the sea-floor -- later dried to form shales. Graptolites in sea and on muds.
-stiaE2_2. Biblrian times :ihole area uplifted and partly eroded (tima-gap between Ordovician and Silurian at Buzzonia) Intense earth forces crush and fold area into slates.
-Stag p5. Silurian. Test side subsides under inland lake, with shoreline east of BunE,onia Gorge: limestone belts established and Ordovician rocks of east carried west by rivers; re-deposited in lake.
-,-.2Eal. Devonian - Carboniferous times. Region uplifted entirely. Erosion of Ordovician slates and of More recent Silurians of west.
-stEp__L. Permian times. Eastern sector submerged below sea, but not so far from shore as in stage I (shoreline close to present Barber's Creel.). Sandstones deposited in horizontal layers.
-Post-Pori:lian times, Bodily uplift of whole area, and erosion to present contours.
-The story is there complete in the main, and only one minor aspect reycains. During the Zilurian activity, molten rock froz]L deep down in the earth's crust welled up into the areas near the present 1:arl.11an. This, on coolias &alre rise to granite and poIrpbyry in these regions.
-Thus we may see in the story of the ancient Shoalhaven area, not a tale of hills eternal and timeless lands, but of a varied inter-change of land and sea. On future walks, you may see yourself the story revealed; the folded slates of the lower gorge, the sandstones of the upper, and the limestones L.12 Bungo-nia -- pieces of a history before tla6- afxma-of
 "REUNION?" DID YOU SAY "FEDERATION REUNION?"
 Vr. -wsmi. A