[Rockhounds] New Madrid fault / Rivers

[Jim Daly]

I suspect that the Delaware Water Gap ( on the Delaware River between northern New Jersey and Pennsylvania) might be another example, and part of the same rift.
Jim
--- On Sat, 3/28/09, Mark Sigouin <marksigouin at verizon.net> wrote:


From: Mark Sigouin <marksigouin at verizon.net>
Subject: Re: [Rockhounds] New Madrid fault / Rivers
To: "Dora Smith" <tiggernut24 at yahoo.com>, "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" <rockhounds at lists.drizzle.com>
Date: Saturday, March 28, 2009, 9:43 AM


The Hudson River also occupies a failed rift. From my geology classes years and years ago, when a rift forms causing two plates to move from each other, at points along the successful rift there occur third unsuccessful rifts where the continental crust doesn't pull apart.  But the rift presents a weak point for erosion to work on creating a river valley that often ignores other hydrogeologic flow structure controls.  So you get rivers that cut through mountain ridges rather than going around them.


----- Original Message ----- From: "Dora Smith" <tiggernut24 at yahoo.com>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" <rockhounds at lists.drizzle.com>
Sent: Saturday, March 28, 2009 12:26 PM
Subject: Re: [Rockhounds] New Madrid fault / Rivers


> I really didn't think that the Mississippi River was a coincidence.
> 
> Yours,
> Dora Smith
> Austin, TX
> tiggernut24 at yahoo.com
> ----- Original Message ----- From: "Mr EMan" <mstreman53 at yahoo.com>
> To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" <rockhounds at lists.drizzle.com>
> Sent: Friday, March 27, 2009 11:45 AM
> Subject: Re: [Rockhounds] New Madrid fault / Rivers
> 
> 
>> 
>> --- On Wed, 3/25/09, Alan Goldstein <deepskyspy at insightbb.com> wrote:
>> 
>>> The failed rift dates to the Precambrian - about 700 million
>>> years ago.
>> 
>> Sorry, Alan you are correct-- my brain only holds so much trivia without frequent "reactivation".  200-180 mya was the reactivation age not the original formation age--mia culpa.
>> 
>> Agreed,Rift zones were great influences of drainage basins and paleo-rivers. Now we can add the St Lawrence River to the list.  The recent History Channel episode:  How the Earth Was Made: The Great Lakes brought up the discovery that Lake Superior and Lake Ontario have failed rifts at there long axis which laid the foundation for a paleo river drainage basin that probably drained a region (possibly including the paleo-Mississippi) to the north then east.
>> 
>> Elton
>> 
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