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Chris White · @Ceedave
151 followers · 278 posts · Server sciencemastodon.com
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A small of the Member of the

These are in the Group, which is currently dated to . The Squantum Member was interpreted as a , possibly associated with the , although there a scant signs like scratched pebbles or faceted cobbles. It is currently commonly interpreted as a (debris flow). Details in captions.

#outcrop #squantum #roxbury #conglomerate #rocks #bostonbay #Neoproterozoic #tillite #gaskiers #glaciation #debrite #geology #Glacier #turbidite #quincy #boston #massachusetts #newengland

Last updated 1 year ago
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Chris White · @Ceedave
128 followers · 241 posts · Server sciencemastodon.com
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Anomalous pebble in layered

An angular pebble is conformably surrounded by argillaceous and sandy layers in this of the Member of the Conglomerate. The wide range of clast sizes led to an interpretation as a thru the 1970s, but the Squantum Member is now mostly interpreted as a ( or ). My .

#sedimentary #rock #photograph #Neoproterozoic #squantum #roxbury #glacial #tillite #debrisflow #debrite #turbidite #photo #boston #fieldtrip #umassboston

Last updated 1 year ago
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Chris White · @Ceedave
127 followers · 237 posts · Server sciencemastodon.com
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Deformed bedding in meta#sedimentary

The horizontal bedding of the Member of the Conglomerate (, Bay Group) has been disturbed locally.

In the interpretation of the Squantum (favored through at least the 1970s), the distortion might be caused by glaciotectonic drag at the ice base. The current interpretation as a or would probably attribute the deformations to synsedimentary slumping. My .

#rocks #squantum #roxbury #Neoproterozoic #boston #glacial #tillite #debrite #turbidite #photo #fieldtrip

Last updated 1 year ago
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Chris White · @Ceedave
126 followers · 235 posts · Server sciencemastodon.com
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Rapid changes in size in

The Member of the Conglomerate ( Bay Group) transitions from sandstone, to almost-clast-supported conglomerate, to laminated argillite…in about 25 cm. Fifty years ago, it was interpreted as a deposit and called the Squantum , presumably associated with the Glaciation. Paucity of evidence (e.g., few scratches or faceted clasts) suggests a debris flow. My .

#clast #sedimentary #rocks #Neoproterozoic #squantum #roxbury #boston #glacial #tillite #gaskiers #photo

Last updated 1 year ago
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Chris White · @Ceedave
124 followers · 228 posts · Server sciencemastodon.com
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Interbedded argillaceous & tuffaceous

These photos are of , exposed above the Member of the Conglomerate (). Prior to the 1970s or so, the Squantum Member was interpreted as sediments; it's now broadly interpreted as debris flows, with the Cambridge being distal turbidites overlying it. I lead a field trip here for . See captions.

65mm

#sediments #cambridge #argillite #squantum #roxbury #Neoproterozoic #glacial #umassboston #outcrop #fieldtrip #photo #rocks #tuff #fufjilm #venus #macro #quincy

Last updated 1 year ago
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Chris White · @Ceedave
124 followers · 228 posts · Server sciencemastodon.com
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Interbedded argillaceous & tuffaceous

These photos are of , exposed above the Member of the Conglomerate (). Prior to the 1970s or so, the Squantum Member was interpreted as sediments; it's now broadly interpreted as debris flows, with the Cambridge being distal turbidites overlying it. I lead a field trip here for . See captions.

15mm

#sediments #cambridge #argillite #squantum #roxbury #Neoproterozoic #glacial #umassboston #outcrop #fieldtrip #photo #rocks #tuff #fufjilm #venus #macro #quincy

Last updated 1 year ago
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Chris White · @Ceedave
124 followers · 228 posts · Server sciencemastodon.com
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Interbedded argillaceous & tuffaceous

These photos are of , exposed above the Member of the Conglomerate (). Prior to the 1970s or so, the Squantum Member was interpreted as sediments; it's now broadly interpreted as debris flows, with the Cambridge being distal turbidites overlying it. I lead a field trip here for . See captions.

15mm

#sediments #cambridge #argillite #squantum #roxbury #Neoproterozoic #glacial #umassboston #outcrop #fieldtrip #photo #rocks #tuff #fufjilm #venus #macro #quincy

Last updated 1 year ago
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Chris White · @Ceedave
82 followers · 80 posts · Server sciencemastodon.com
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Fort Hill, Crossing, , ,
Fort Hill is named for the fort (not this tower!) erected on it between the confrontation at Concord in April 1775 and British evacuation of Boston when Washington et al. moved guns onto Heights in March 1776 (independence “declared” in July 1776). The hill is capped by the Roxbury Conglomerate (, ~600 Ma), which sports rakish glacial striations.

#roxbury #boston #massachusetts #usa #dorchester #Neoproterozoic #Pleistocene #history #geology #fujifilm #glacial #newengland

Last updated 2 years ago
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Chris White · @Ceedave
82 followers · 80 posts · Server sciencemastodon.com
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Fort Hill, Crossing, , ,
Fort Hill is named for the fort (not this tower!) erected on it between the confrontation at Concord in April 1775 and British evacuation of Boston when Washington et al. moved guns onto Heights in March 1776 (independence “declared” in July 1776). The hill is capped by the Roxbury Conglomerate (, ~600 Ma), which sports rakish glacial striations.

#roxbury #boston #massachusetts #usa #dorchester #Neoproterozoic #Pleistocene #history #geology #fujifilm #glacial #newengland

Last updated 2 years ago
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Chris White · @Ceedave
82 followers · 80 posts · Server sciencemastodon.com
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Fort Hill, Crossing, , ,
Fort Hill is named for the fort erected on it in the interval between the confrontation at Concord in April 1775 and British evacuation of Boston when Washington et al. moved guns onto Heights in March 1776 (independence was “declared” in July 1776). The hill is capped by the Roxbury Conglomerate (, ~600 Ma), which sports rakish glacial striations.

#roxbury #boston #massachusetts #usa #dorchester #Neoproterozoic #Pleistocene #history #geology #fujifilm #glacial #newengland

Last updated 2 years ago
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Chris White · @Ceedave
29 followers · 15 posts · Server sciencemastodon.com
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Pleistocene glacial striations on Devonian and Neoproterozoic rock in New England. Savin Hill, Middlesex Fells, and Mt Monadnock. See captions for details.

#rocks #glaciology #boston #middlesexfells #mountmonadnock #sedimentary #medford #Neoproterozoic #devonian #Pleistocene

Last updated 2 years ago
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Chris White · @Ceedave
22 followers · 11 posts · Server sciencemastodon.com
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Last set of examples of soft sediment deformation in the. Squantum Member of the Roxbury Conglomerate, Boston Bay Group; Neoproterozoic and approximately contemporaneous with Gaskiers glaciation.

Although previously interpreted as a tillite (it is still sometimes referred to as the “Squantum Tillite), the “consensus” is now debris flows and turbidites.

#geology #sedimentology #turbidites #glaciology #boston #Neoproterozoic #geosciences #sedimentary #rocks

Last updated 2 years ago
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Christopher D. White · @Ceedave
5 followers · 5 posts · Server sciencemastodon.com
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Possible dropstone in the Neoproterozoic Squantum Member of the Roxbury Conglomerate, Quincy, Massachusetts USA. See previous posts for more background.

#geology #glaciology #turbidites #Neoproterozoic #sedimentary #conglomerate #rocks

Last updated 2 years ago
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