Presentation on theme: "Adirondack Geology: Old Rocks and New Mountains: Glenn A. Richard."— Presentation transcript:
1Adirondack Geology:Old RocksandNew Mountains:Glenn A. Richard
2The Adirondacks are a dome of old rock (1 The Adirondacks are a dome of old rock (1.1 billion years), surrounded by much younger rock (less than 600 million years)Relief Map of Adirondacks
3Map 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.
4Roadless areas are undeveloped 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).Roads
5Mount Marcy, highest point in New York (5344’), from Haystack 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).
6Shore of Lake Champlain (elevation 95 feet) from eastern Adirondacks Shore of Lake Champlain (elevation 95 feet) from eastern Adirondacks. Lowest elevation in Adirondacks.
7Haystack from Marcy – July 2, 2001 Haystack from Marcy – July 2, Rugged topography caused by faulting, uplifting, erosion by water and glacial ice.
8Gothics – September 2, 2001- Note steep rockslides
9Picea rubens and Abies balsamea just below tree line on Haystack, third highest peak in the state at 4960’.
10Cross section of Earth Layers of the Earth: Inner Core Outer Core MantleCrustDiagram by Keelin MurphyCrust and very upper mantle are hard rock, called lithosphere.Lithosphere divided into tectonic plates. Plates are in motion – several centimeters per year – PLATE TECTONICSOrogeny: Collision of plates can build mountains (Example: Himalayas now rising due to current collision of Indian and Asian plates).
11Plate Boundaries Transform: San Andreas Fault Diagram by Keelin MurphyPlate BoundariesTransform: San Andreas FaultDivergent: East Pacific RiseConvergent: West Coast of South America -Andes forming here
121.3 Billion Years Ago: Pre-Grenville Ocean Fossil stromatolite (blue-green alga, 1.3 bya) near Balmat in western Adirondacks. From Pre-Grenville Ocean prior to Grenville Orogeny .
131.1 Billion Years Ago: Grenville Orogeny 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.
14Boudinage in migmatite, northwestern Adirondacks formed during Grenville Orogeny 1.1 bya
15650 Million Years Ago: Grenville Supercontinent Breaks Up Lake Placid from Whiteface. Shape is controlled by a group of faults that formed about 650 million years ago, when Grenville Supercontinent split up.
16Colden, Avalanche Pass, Algonquin, Indian Pass, Wallface Colden, Avalanche Pass, Algonquin, Indian Pass, Wallface. Passes are valleys formed along faults.
17Faulting helps to create valleys and basins for streams and lakes. Lake Placid from Whiteface. Shape is controlled by some of the faults that formed about 650 million years ago.
18Diabase dike (650 mya) in western Adirondacks intruded during breakup of Grenville supercontinent.
19500 Million Years Ago: A Warm Shallow Sea 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.
20Beginning 60 to 15 Million Years Ago: Adirondack Mountains Form 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.
21Beginning 1.6 Million Years Ago: Continental and Alpine Glaciation Glacial erratic near Debar Mountain in northern Adirondacks
22Potsdam Sandstone left by ice sheet on Poke-O-Moonshine
23Au Sable Chasm with Potsdam Sandstone Au Sable Chasm with Potsdam Sandstone. Au Sable River has cut into the sandstone as uplift occurs.
24Heart Lake from Mount Jo. Some consider it to be a glacial kettle.
25Snow on Saint Regis Mountain with fall color at lower elevations, shows climate variation with elevation.
26Mountain-ash on Saint Regis Mountain, October 8, 2000
27Vegetation reflects geology Red oak at Lake Champlain shore. Soil in Adirondacks is mostly acid.
28Walking fern near Lake Champlain shoreline favors habitats where calcite is present.
29Cystopteris bulbifera at Cascade Lakes favors habitats where calcite is present.
30Pickerelweed in marsh at Lake Champlain shoreline
31Cotton grass on floating bog mat at Sunday Pond Cotton grass on floating bog mat at Sunday Pond. Peat is acidic and water is low in oxygen and dissolved nutrients
32Insectivorous pitcher plant on Sunday Pond bog mat Insectivorous pitcher plant on Sunday Pond bog mat. Bog water is low in nitrates.
33Insectivorous round-leaved sundew on Sunday Pond bog mat
34Labrador tea on Sunday Pond bog mat favors wet acid conditions.
53In Summary: 1.3 Billion Years Ago – Warm shallow pre-Grenville Sea 1.1 Billion Years Ago - Grenville Orogeny650 Million Years Ago – Grenville Supercontinent breaks up500 Million Years Ago – Warm shallow sea, Postdam Sandstone60 to 15 Million Years Ago – Adirondacks begin to rise1.6 Million Years Ago – Ice Ages begin
54Some books:Rocks And Routes of the North Country – Bradford VanDiverGeology of New York: A Simplified Account – University of the State of New YorkRoadside Geology of New York - Bradford VanDiverBogs of the Northeast – Charles W. JohnsonA Map:New York State Geologic Highway Map – University of the State of New York