AAMN Field Trip Canyon Lake Gorge
Thanks to Cindy Sims and Sam Glass for providing the photographs

J.W. and Dr. Ward brief us about the gorge formation before the hike (44kb) Dr. Ward and Cindy discuss how recent floodwaters carved the gorge (63kb) Looking downstream towards the road (42kb) Dr. Ward describes the deposition of marine organisms over 100 million years ago (47kb) Dr. Ward shows the tidal deposits found in ancient stream channels (47kb)
Dr. Ward shows Joanne the Equisetatae fossils found in the channels (42kb) The darker channels are distinct from the lighter limestone matrix (57kb) Dr. Ward points at a network of trace fossils found in the limestone bed (58kb) The trace fossils are burrowings of Cretaceous marine organisms (67kb) Looking at the alternating beds of limestones and marls typical of a shallow sea environment (38kb)
Dr. Ward points at trace fossils formed by crustaceans scooping up seafloor mud (57kb) Aggregate of fossilized serlupid worm tubes from an ancient marine reef (53kb) Dr. Ward explains why unoxidized limestone remains darker in color (41kb) Limestone fractures are part of the erosion process (32kb) Water flows along vertical limestone joints (48kb)
Water also flows along horizontal limestone bedding planes (45kb) Cretaceous limestones contain numerous varieties of fossils (39kb) Dr. Ward identifies fossils typical to Texas limestones (59kb) Our group gathered many fossils in a short period of time (46kb) Our group pauses for Cindy to take our photograph (42kb)
Wave ripples are evidence of a shallow surf zone (53kb) Dr. Ward stands on the Caryocorbula martinae fossil layer (51kb) This bivalve fossil layer is the boundary between the Upper and Lower Glen Rose limestone beds (40kb) The powerful forces of the flood washed away the topsoil and exposed the underlying limestone (63kb) Looking downstream towards the road and seeing the Glen Rose limestone formation (37kb)
Standing on top of Upper Glen Rose limestone (40kb) Looking at the Hidden Valley fault dip (7kb) This fault is part of the greater Balcones fault zone (33kb) Looking at the fault trend intersecting with the gorge cut (48kb) Water flows along the fault plane underneath the surface (43kb)
Standing near the fault plane (62kb) Slickensides occur when one side of the fault plane scrapes against the other side (51kb) Dr. Ward shows how angular beds form from shoreline deposition (62kb) Walking across a pod of sedimentation from a Pleistocene sinkhole long eroded away (60kb) Looking at water flowing in a karst environment (45kb)
Looking at fossils of the rudistid Toucasia hancockensis found in Upper Glen Rose limestone (41kb) The rudistids became extinct after the Cretaceous period (59kb) Dr. Ward standing near a dinosaur track (64kb) The dinosaur tracks follow the ancient shoreline (65kb) Highlighted tracks for better visibility (65kb)