FTELD TRIP ACROSS THE APPALACHTAN OROGENIC BELT

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Which way do the rocks dip? (You are facing east). 8 Which way would you drive to find ol4er rocks? younger rocks? Which way to the anticline? to the EEsLine? This quarry is a veritable gold urine of interesting inported rock typesi we could spend the whole day here. Notice especially the coarse-grained red s-andstone: we'I} see more of that the next stop. Jurassic, from the rift basin. dark gray, coarse-grained ggbbre: the coarse-grained, intrusive equivalent of basalt. An igneous rock - look at the crystals and the difference between its texture and the sandstonets. Jurassic, from the rift basin.
STOP 4: 9 <strong>THE</strong> BIKE STORE', MOHNTON The vacant lot just beyond the Harley-Davidson shop can be soft and wet, and you need to be careful to stick to the higher ground. Stay away from the highway, because itts a blind curve with high-speed traffic. This site is located within the IIESOZOIC RIFT BASIil (labelled rrTriassictr on Figure L ) that runs continuously from New York state to Virginia. The basins are of Late Triassic and Early Jurassic n9€r are younger than anything in the Appalachian orogenic be1t, and are not genetically related to Appalachian events in any way. The Appalachian orogenic belt involved compressive deformation and shortening of the earth's crust; the Mesozoic rift basins involved extensional deformation and lengthening of the crust. The extension is related to the breqlsup of Pangea - the rifting apart of the supercontinent of Pangea in early l.lesozoic tine. This rift basin is one (of rnany) early, failed attenpts at breakup; the new Atlantic Ocean didn't open up here, but opened later farther east, and preserved this basin on the segnent of continent that drifted west from the nid-Atlantic ridge. This rift basin was a precursor of the new Atlantic ocean. The rift basin has a wedge shape, thickest on the north edge and thinningr to zero on the south edge. The sedimentary strata dip to the north. Look across the highway to the north; the ridge on the skyline is the north edge of the basin. The north edge is marked by a norrnal f4ult, in which the south side, our side, yras dropped down. The high lands on the upthrown side were subjected to intense erosion, and generated coarse sand and gravel sediment that becarne the sandstones and conglomerates of this outcrop. The skyline ridge to the north is underlain by older rocks that were the very source for the pebbles in this conglomerate. The rift basin contaLns two rnajor kinds of rock: terrigenous, red, clastic sedinentary rocks ranging fron shale to sandstone and conglomerate, and intrusive igneous rocks of gabbro composition (that we saw at the previous stop). The rocks here are cobble and boulder corxrlorcrates and cq?rse:grrained rFd sandstones. observe in these rocks: the in the conglomerates, Are they snooth or angUlAr? Are they sorted into beds of sinilar clast sizer oF are they rlnsorted and mixed together regardless of size? How far alray (relatively) is this location from the source of
Page 1 and 2: GEOIOGY 106 FTELD TRIP ACROSS THE A
Page 3: REGTONAL GEOLOGTC SETT TNG The next
Page 7 and 8: . Varlicot atlta (hrtlcol .rogsroho
Page 9 and 10: C*;:;il 't {r ( i:$-*
Page 11 and 12: i'.iii :iii.'i:j l3 lz ll lo 1 ?_-J
Page 13 and 14: STOP 1: h,INDY HILLS BRIDGE Stop L,
Page 15 and 16: There were at these rocks. 5 least
Page 17: STOP 3: G()LD 7 , N GREEN CIUARRY,
Page 21 and 22: 11 STOP 5: STONE CLIFF PARK, READ I
Page 23 and 24: 1_3 Work out a sequence of eyents i
Page 25 and 26: 15 Note the regularity of the beddi
Page 27 and 28: 17 sToP 7 - DEER LAKE This is an ab
Page 29 and 30: 18 as representing shallow, gently
Page 31 and 32: sroP 70: 20 LAVELLE I I This exposu
Page 33 and 34: 22 STOP 77: LAVELLE TTT . This is a
Page 35 and 36: t l+{ o OJ 0) .o r0 E F (n F.l fr U
Page 37 and 38: sToP 73: DTNNER STOP 25 BEAR VALLEY
Page 39 and 40: surface of the rocks just below the
Page 41: Pecopter:is sp. Annu,a.ria sp. lieu

FTELD TRIP ACROSS THE APPALACHTAN OROGENIC BELT

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