The cross section below shows the rocks of the Watchung Reservation and surrounding area, revealing the relative positions of the lava flows that erupted in this region and the sedimentary rock layers between them. A Walk Back in Time The Ruth Canstein Yablonsky Self-Guided Geology Trail click here to view on a smart phone NOTES Trailside Nature & Science Center 452 New Providence Road, Mountainside, NJ A SERVICE OF THE UNION COUNTY BOARD OF UNION COUNTY (908) 789-3670 CHOSEN FREEHOLDERS We’re Connected to You! The Ruth Canstein Yablonsky Glossary basalt a fine-grained, dark-colored Mesozoic a span of geologic time from Self-Guided Geology Trail igneous rock. approximately 225 million years ago to 71 million years This booklet will act as a guide for a short hike to interpret the geological history bedrock solid rock found in the same area as it was formed. ago, and divided into of the Watchung Reservation. The trail is about one mile long, and all the stops smaller units called Triassic, described in this booklet are marked with corresponding numbers on the trail. beds layers of sedimentary rock. Jurassic and Cretaceous. conglomerate sedimentary rock made of oxidation a chemical reaction “Watchung” is a Lenape word meaning “high hill”. The Watchung Mountains have an rounded pebbles cemented combining with oxygen. elevation of about 600 feet above sea level. As you travel southeast, these high hills are the together by a mineral last rise before the gently rolling lowland that extends from Rt. 22 through appropriately substance (matrix) . Pangaea supercontinent that broke named towns like Westfield and Plainfield to the Jersey shore. apart in early Mesozoic time, erosion processes (running forming separate continents The Watchung Reservation is located in the water, ice and wind) which and the Atlantic Ocean. loosen and transport rock central part of a large geologic area called the on the earth’s surface. puddingstone a type of conglomerate. Newark Basin. The rocks were formed about quarry an open cliff face where rocks 200 million years ago, during the late Triassic glacial erratic a rock fragment different from the rock on which it are removed to be used for period. At that time, all of the continents were building -stone, paving, etc. joined into one landmass called Pangaea. lies, having been transported Forces deep within the earth caused this by a glacier. quartzite a metamorphosed form of sandstone. super-continent to gradually pull apart, glacier a thick mass of ice, formed forming the Atlantic Ocean and the continents by compacted snow, with sandstone sedimentary rock composed we know today. motion in a definite direction. of sand-sized minerals or rock grains. hematite a red-colored iron ore. The Watchung Reservation began as a broad sedimentary rocks formed from fragments valley in which multiple layers of mud and igneous rock formed by the cooling of of other rocks, compressed sand were deposited. Over millions of years, the layers gradually hardened into sedimentary molten material. or cemented together. rock. As the crust stretched, cracks formed and lava rose through them and spread onto the impermeable having a structure that does shale sedimentary rock composed surface. The lava cooled and hardened into igneous rock. Three series of lava flows over the not permit water to move of mud that is a mix of clay course of several million years, were separated from one another by layers of sand and mud through it. materials and other fine now compacted into rock called sandstone and shale. Continued crustal stretching caused Jurassic the second of three geologic textured mineral fragments. the valley to sink further and become tilted to the northwest. As millions of years passed, the periods in the Mesozoic era soil creep slow movement of rock rocks were eroded to produce the surface we see today. (180 - 135 million years ago). fragments down a gentle The Earth’s climate cooled significantly about one million lava molten igneous rock that slope. years ago, causing snow and ice to accumulate and form great flows out and cools on the spring a small pond or stream of ice sheets called continental glaciers. There were four major surface of the Earth. water flowing naturally from glacial periods during which the ice moved across portions lithify to form rock by cementing the earth. of North America, including northern New Jersey. Soil and or compressing sediments. Trap rock Scandinavian for “stairs,” rocks of all sizes were frozen into the glacier and transported matrix mineral material by which construction term for basalt. south. When the ice melted, these materials settled to the rock fragments are cemented. Triassic earliest of three Geologic ground to form a blanket of sediments over the surface. The metamorphic rocks that have in some way periods in Mesozoic era (225 glaciers did not travel much further south than the present been changed by - 180 million years ago). day Watchung Reservation. Click here to download this temperature and pressure. tour onto your smartphone Gray Shale 11 (As you walk up the trail, notice many of Ruth 10 the smaller trees with the lower portion of Canstein their trunks curved in a downhill direction. Lake Surprise 8 This is evidence of a form of erosion Yablonsky 9 called “soil creep.” Under the influence of gravity, the soil on steep hillsides moves Teacher & 7 slowly downhill. As the trees grow, they Naturalist 6 constantly adjust their growth direction to Camping Fields remain upright.) 5 4 Master Gardeners 11 At this stop, the thin papery pieces Loop of shale are gray. This color indicates For over three decades Ruth has been teaching that these sediments were continuously children about the natural world. both at the sci- 3 1 covered with water, probably in a deeper ence center and in visits to elementary schools. Parking Trail = 1 mi. Lot part of a lake or swamp. The red and She is a teacher’s teacher, always encouraging 2 gray shales are part of a larger unit called children. the Feltville Formation. This formation is In recognition of her achievements, Yablonsky Self-Guided Geology Trail approximately 600 feet thick and overlies was awarded the Alliance for New Jersey Envi- the basalt of ronmental Education’s Patricia R. Kane Lifetime the west to see the second ridge. The the Orange 1 Visitor Center Achievement Award in 2010 for excellence for The self-guided hike begins on low area in between the ridges formed Mountain environmental education. the lower level of the Nature Center, to as the softer sandstones and shales Formation that Yablonsky grew up in The Bronx, went to Hunter provide you with an eroded more rapidly. The marked outcrop forms the First College and then to the University of Michigan, overview of what is basalt, which formed the step-like Watchung where she earned her Master’s Degree in geol- you will see on the structure as the lava cooled. Basalt is Mountain. ogy. In 1985, Yablonsky came to Trailside. trail, and a graphic also called trap The Feltville history of the area. rock, from the Formation is, in Naming the trail after her is the perfect honor, for as she said in an interview two years ago: Please take time to Scandinavian turn, covered by view the exhibits of word “treppe” another flow of “My passion is geology If you have an under- basalt minerals and which means lava known as the Preakness Basalt. This standing of the basics of geology, anywhere in fluorescent minerals stair. The forms the Second Watchung Mountain, the world you go you have an understanding of (in the Discovery chemical which rises on the other side of the why things are the way they are.“ Room) as well. weathering and swampy area. When you leave the Visitor Center, turn oxidation of the right and walk to the highest edge of the iron-rich basalt This concludes the geology hike. You parking lot to the marked outcrop. produces its rusty color. Many trap rock may turn around and walk back up the quarries are located in the Watchung Orange Trail to the parking lot or you may Mountains. The rock is blasted from the continue up the bridle path, and bear 2 Basalt Outcrop quarry walls and crushed to produce right, which will take you to The Loop In the parking lot, you are standing gravel for road stone and asphalt. picnic area. on the ridge of the First Watchung Cross the parking lot and continue to Mountain, formed by the first, and oldest, the street entrance. Turn right and walk lava flow 200 million years ago. Look downhill on the paved road, as far as the down the hill, behind the trees, toward lower edge of the parking lot. proceed down the trail, you will notice the 6 Glacial outside bend banks on each side are steep. Each time of the meander, a hiker walks down the trail, a little soil Erratics eroding the 3 Erosion at Parking Lot These boulders is loosened. When it rains, the loosened stream bank there When rain falls on vegetated areas, are glacial soil is washed down hill. At one time, the more quickly. much of it is absorbed by the plants and erratics, too. narrow valley you are walking did not The faster water soil. When it falls on an The term “glacial exist. Much of the soil and rock has been moves, the more impermeable surface erratic” refers transported by erosion, washed away by sediment it can such as this paved to any rock that rainwater flowing down the slope. carry, transporting parking area, it cannot was frozen into Continue down trail.