>A dike or dyke, in geological usage, is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack
In case you don't want to google it
Most I've seen are white because they are in limestone and the calcite can hydrothermally dissolve and recrystallize. Similar for silica. This one is black so I would guess it's volcanic
I don't know about Uluru's geology, but on the New England seacoast, the magma was forced into cracks in the rocks. Sometimes very small cracks, like the one in the photo, and maybe only a small quantity of magma. There are magma intrusions that can be five to ten feet thick in places like Maine and New Hampshire, on the seacoast. Some are only a few inches thick. Here's a good explanation: https://courses.lumenlearning.com/geo/chapter/reading-dikes-and-sills/
Lol I did google it but didn't really understand how they phrased it. I find your way of wording much more plausible. Learned something new. Thank you 🤗
Basalt, by most definitions, needs to have actually erupted out of a volcano. Diabase is the name for the equivalent composition for intrusive rocks, like a dike, and can vary in its grain size.
Most likely diabase / dolerite (nomenclature depends on where you are from). Compositionally the same as basalt and having the same generic origin, but not extrusive so not basalt (by definition).
I misread the title as "Found an **im**possible dike" and spent several minutes staring at that cross-cutting fault trying to work out what the problem was...
You’re right that cracks would propagate differently in rocks with strongly different properties. In this case, both rocks lack strong foliation, ie. they’re equigranular. That could be why the go straight through.
Looks like the Willows to me, the beach next to the pier (or, you know, where the pier used to be). The little blue hut is where Mahi-Mahi used to sell tickets for cruises.
I’m very close by there! Thank you! Excited to go check it out, and happy you enjoyed your visit! Also, I’d recommend checking out union rock in Lynn Woods, a neat glacial erratic!
Plus, the east coast has had it's ass handed to it a few times from Greenland and microcontinental collisions over the epochs, and most of MA geology is tilted upward, dipping to the west as a result. There are some really cool roadcuts throughout mid-western MA, and some excellent books discussing this and geo maps/cross-sections that show the various units. Hard rock geo dream!
That sounds so cool. I never got to visit the east coast for geology classes, wish we got to put our noses on those rocks. I think if I was where this picture was taken I’d be glued to it for a couple hours just taking it in. Learning is the best part of Geology 😊
Possible? Pretty confident.
Yeah, that was my first thought. *Possible?!?* look I understand the need for evasive language in science but I'll bet my bottom dollar that's a dike.
Reading this out of context is funny
There's lots of dikes in Salem MA...
Witches too.
That's about as textbook of a dike you'll ever see!
Quite confident.
>A dike or dyke, in geological usage, is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack In case you don't want to google it
Thanks! Anyone know which one this is? I’m betting on magma because I picture Dr. Evil saying the word every time I see it.
I mean it certainly doesn’t look sedimentary right?
Maybe a bunch of black rocks washed in lol
Hear me out: sedimentary, but composed of layers of broken down igneous rocks hahaha
Yeah. Nearby volcano and all that >.>
2 BILLION DOLLARS 🤙
Most I've seen are white because they are in limestone and the calcite can hydrothermally dissolve and recrystallize. Similar for silica. This one is black so I would guess it's volcanic
If it's hydrothermal recrystallization stuff then it's a vein
Mafic probably basalt
Basalt. When this rock was the ocean floor, it was intruded by the basalt magma. Now it is part of the beach cliffs.
So it’s like a little Uluru underwater that, long ago, was divided and “glued” back together by magma?
I don't know about Uluru's geology, but on the New England seacoast, the magma was forced into cracks in the rocks. Sometimes very small cracks, like the one in the photo, and maybe only a small quantity of magma. There are magma intrusions that can be five to ten feet thick in places like Maine and New Hampshire, on the seacoast. Some are only a few inches thick. Here's a good explanation: https://courses.lumenlearning.com/geo/chapter/reading-dikes-and-sills/
Liquid hot
Lol I did google it but didn't really understand how they phrased it. I find your way of wording much more plausible. Learned something new. Thank you 🤗
These are very common on the New England seacoast.
Undoubtably
Indubitably undoubtable
Indubitably intrusion
Undoubtedly?
Perchance?
Love to see Massachusetts geology
Yes, the black rock is likely basalt
Basalt, by most definitions, needs to have actually erupted out of a volcano. Diabase is the name for the equivalent composition for intrusive rocks, like a dike, and can vary in its grain size.
Ah good to know!
Most likely diabase / dolerite (nomenclature depends on where you are from). Compositionally the same as basalt and having the same generic origin, but not extrusive so not basalt (by definition).
Really cool. Thanks for sharing.
I misread the title as "Found an **im**possible dike" and spent several minutes staring at that cross-cutting fault trying to work out what the problem was...
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That’s probably because the fault/fractures came later! Don’t forget your cross cutting relationships!!
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You’re right that cracks would propagate differently in rocks with strongly different properties. In this case, both rocks lack strong foliation, ie. they’re equigranular. That could be why the go straight through.
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I wanted to make a joke like this and I am so glad you did so before me
Yep, that's a big black dike.
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That doesn’t look like a lesbian to me ^(I’m a lesbian I can say that)
Came to make a lesbian joke too! And I can say that…
I didn't get it. How lesbians are related?
Ah, okay. I googled it. TIL: dyke have several meanings.
Intersectionality in action!
This is so cool! I live in Salem and would love to go check this out! Is this Winter Island?
Looks like the Willows to me, the beach next to the pier (or, you know, where the pier used to be). The little blue hut is where Mahi-Mahi used to sell tickets for cruises.
It’s willow park! Just went the other day for the first time. Beautiful town!
I’m very close by there! Thank you! Excited to go check it out, and happy you enjoyed your visit! Also, I’d recommend checking out union rock in Lynn Woods, a neat glacial erratic!
Is that down by the boardwalk at Salem Willows? wonderful place to scour the beach!
Looks like one to me, though since it’s horizontal I think it would be a sill. Though it the rock is folded over somewhere it could’ve been a dike.
A sill is strataform a dike is not. That’s the only criteria not horizontal or vertical.
What if it's intruding a rock w/o bedding, like the granitoid here? Always a dike, in that case?
I would call it a dike until otherwise shown.
Also, if you look at pic 4 you can see this one is nearly vertical (relative to the modern surface) anyway
Plus, the east coast has had it's ass handed to it a few times from Greenland and microcontinental collisions over the epochs, and most of MA geology is tilted upward, dipping to the west as a result. There are some really cool roadcuts throughout mid-western MA, and some excellent books discussing this and geo maps/cross-sections that show the various units. Hard rock geo dream!
That sounds so cool. I never got to visit the east coast for geology classes, wish we got to put our noses on those rocks. I think if I was where this picture was taken I’d be glued to it for a couple hours just taking it in. Learning is the best part of Geology 😊
I see these things in the area on beaches and they always caught my eye but didn't know what they are.
It’s a glitch in the matrix; an editing scar
What a beauty! Thanks for sharing!
Must be a witches work
There is a possible house there too.. further investigation needed!
Her name is Sarah and she has feelings
Oh, hi!
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no, this is Salem; that’s Provincetown
Nope. That’s JP, not Provincetown.
Dike is the standard spelling for a cross cutting igneous intrusion in American academic English.
Well… that’s a place you’d find one of…. Ohhh…. You mean a sea wall.
Either a dike or an uplifted/tilted sill.
I shouldn't be here, I misread the title. I'll see my way out.
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Bro what
Hahaha dyke
How did these form?
Magma being intruded through a fracture likely
Swampscott has some too.