Chris White · @Ceedave
151 followers · 278 posts · Server sciencemastodon.com
A small #outcrop of the #Squantum Member of the #Roxbury #Conglomerate
These #rocks are in the #BostonBay Group, which is currently dated to #Neoproterozoic. The Squantum Member was interpreted as a #tillite, possibly associated with the #Gaskiers #glaciation, although there a scant signs like scratched pebbles or faceted cobbles. It is currently commonly interpreted as a #debrite (debris flow). Details in captions.
#geology #glacier #turbidite #Quincy #Boston #Massachusetts #NewEngland
#outcrop #squantum #roxbury #conglomerate #rocks #bostonbay #Neoproterozoic #tillite #gaskiers #glaciation #debrite #geology #Glacier #turbidite #quincy #boston #massachusetts #newengland
Chris White · @Ceedave
126 followers · 235 posts · Server sciencemastodon.com
Rapid changes in #clast size in #sedimentary #rocks
The #Neoproterozoic #Squantum Member of the #Roxbury Conglomerate (#Boston 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 #glacial deposit and called the Squantum #Tillite, presumably associated with the #Gaskiers Glaciation. Paucity of evidence (e.g., few scratches or faceted clasts) suggests a debris flow. My #photo.
#clast #sedimentary #rocks #Neoproterozoic #squantum #roxbury #boston #glacial #tillite #gaskiers #photo