Presentation on theme: "Old Rocks and New Mountains: Natural History of the Adirondacks Glenn A. Richard."— Presentation transcript:
Old Rocks and New Mountains: Natural History of the Adirondacks Glenn A. Richard
Relief Map of Adirondacks The Adirondacks are a dome of old rock (1.1 billion years), surrounded by much younger rock (less than 600 million years)
Map of Streams and Lakes Surface water elevations are primarily controlled by underlying bedrock elevations, rather than the type of bedrock. Radial drainage pattern: Streams flow primarily outward from the center toward the edge. However, drainage in the Adirondacks is also controlled by faults.
Roads Roadless areas are undeveloped. ~43% of 6 million acre Adirondack Park (created in 1892) is owned by the state and belongs to the Forest Preserve (created in 1885).
Mount Marcy, highest point in New York (5344’), from Haystack. Predominant rock type is metanorthosite (Mineralogy: mostly blue labradorite feldpar (high in Ca, some Na, low in K), with some pyroxene).
Shore of Lake Champlain (elevation 95 feet) from eastern Adirondacks. Lowest elevation in Adirondacks.
Haystack from Marcy – July 2, 2001. Rugged topography caused by faulting, uplifting, erosion by water and glacial ice.
Gothics – September 2, 2001- Note steep rockslides
Picea rubens and Abies balsamea just below tree line on Haystack, third highest peak in the state at 4960’.
Cross section of Earth Layers of the Earth: Inner Core Outer Core Mantle Crust Lithosphere divided into tectonic plates. Plates are in motion – several centimeters per year – PLATE TECTONICS Orogeny: Collision of plates can build mountains (Example: Himalayas now rising due to current collision of Indian and Asian plates). Crust and very upper mantle are hard rock, called lithosphere. Diagram by Keelin Murphy
Plate Boundaries Divergent: East Pacific Rise Convergent: West Coast of South America -Andes forming here Transform: San Andreas Fault Diagram by Keelin Murphy
Fossil stromatolite (blue-green alga, 1.3 bya) near Balmat in western Adirondacks. From Pre-Grenville Ocean prior to Grenville Orogeny. 1.3 Billion Years Ago: Pre-Grenville Ocean
Metanorthosite (intruded about 1.15 bya) with labradorite crystal on Noonmark. Smaller amounts of pyroxene are present. Grenville Orogeny metamorphosed the rock about 1.1 bya while it formed the Grenville Supercontinent and the Grenville Mountains. 1.1 Billion Years Ago: Grenville Orogeny
Boudinage in migmatite, northwestern Adirondacks formed during Grenville Orogeny 1.1 bya
Lake Placid from Whiteface. Shape is controlled by a group of faults that formed about 650 million years ago, when Grenville Supercontinent split up. 650 Million Years Ago: Grenville Supercontinent Breaks Up
Colden, Avalanche Pass, Algonquin, Indian Pass, Wallface. Passes are valleys formed along faults.
Lake Placid from Whiteface. Shape is controlled by some of the faults that formed about 650 million years ago. Faulting helps to create valleys and basins for streams and lakes.
Diabase dike (650 mya) in western Adirondacks intruded during breakup of Grenville supercontinent.
Ripple marks on Potsdam Sandstone (500 mya), Ausable Chasm display. Formed in warm shallow sea. Potsdam sandstone probably covered Adirondacks and was eroded from central portions after later uplift. 500 Million Years Ago: A Warm Shallow Sea
Great Range from Noonmark – Adirondacks rising since 60 to 15 million years ago for uncertain reasons. Some have attributed uplift to a hot spot, but there is not much evidence for that. Beginning 60 to 15 Million Years Ago: Adirondack Mountains Form
Glacial erratic near Debar Mountain in northern Adirondacks Beginning 1.6 Million Years Ago: Continental and Alpine Glaciation
Potsdam Sandstone left by ice sheet on Poke-O-Moonshine
Au Sable Chasm with Potsdam Sandstone. Au Sable River has cut into the sandstone as uplift occurs.
Heart Lake from Mount Jo. Some consider it to be a glacial kettle.
Snow on Saint Regis Mountain with fall color at lower elevations, shows climate variation with elevation.
Mountain-ash on Saint Regis Mountain, October 8, 2000
Red oak at Lake Champlain shore. Soil in Adirondacks is mostly acid. Vegetation reflects geology
Common juniper at Lake Champlain shoreline grows well in thin soil.
Maidenhair spleenwort - Asplenium trichomanes fern near Lake Champlain shoreline favors habitats where calcite is present. ** Calcite is uncommon in Adirondacks **
Walking fern near Lake Champlain shoreline favors habitats where calcite is present.
Herb Robert near Lake Champlain shoreline favors habitats where calcite is present.
Braun’s holly fern near Cascade Lakes favors habitats where calcite is present.
Cystopteris bulbifera at Cascade Lakes favors habitats where calcite is present.
Pickerelweed in marsh at Lake Champlain shoreline
Cotton grass on floating bog mat at Sunday Pond. Peat is acidic and water is low in oxygen and dissolved nutrients
Insectivorous pitcher plant on Sunday Pond bog mat. Bog water is low in nitrates.
In Summary: 1.3 Billion Years Ago – Warm shallow pre-Grenville Sea 1.1 Billion Years Ago - Grenville Orogeny 650 Million Years Ago – Grenville Supercontinent breaks up 500 Million Years Ago – Warm shallow sea, Postdam Sandstone 60 to 15 Million Years Ago – Adirondacks begin to rise 1.6 Million Years Ago – Ice Ages begin
Some books: Rocks And Routes of the North Country – Bradford VanDiver Geology of New York: A Simplified Account – University of the State of New York Roadside Geology of New York - Bradford VanDiver Bogs of the Northeast – Charles W. Johnson A Map: New York State Geologic Highway Map – University of the State of New York