[Rockhounds] salmon creek WA

[Thomas Yancey]

It has been enjoyable to watch this exchange of messages, because it 
is a confirmation of Pete Modreski's comment that when a locality 
name is mentioned in a message without any indication of state or 
region, it can be assumed to be refering to a place in the Pacific 
Northwest states of the U.S. In this case, 10 days passed before the 
state was identified.

In many ways this is a very interesting locality. It is the source of 
most of the coprolite concretions that are sold in the rock and 
mineral trade in North America. Large numbers of coprolites have been 
collected in the area for years. While these are generally well 
accepted as coprolites, among residents in the Pacific Northwest 
there has long been controversy about their origin. Many people in 
the region do not believe in a coprolite origin for them and 
publications on geology of the area usually debate this issue. Very 
similar coprolite concretions from other regions (Canada, Madagascar) 
are accepted as coprolites, but the origin of the Salmon Creek 
concretions remains contentious.

These concretions are formed of the mineral siderite and they do not 
retain any fabric of the original feces, although the external 
morphology can be preserved in excellent detail. Many of them are now 
oxidized to iron oxides and the process of mineral change can create 
so much alteration in appearance that their origin cannot be 
determined, contributing to confusion. Also, many that are found in 
the stream bed of Salmon Creek or in older stream gravels have been 
rounded by transport. The sediments of the streambanks also contain 
many concretions of all sizes and it is possible to find virtually a 
continuum between large, irregular iron oxide concretions and well 
formed siderite coprolites. The sediments contain large amounts of 
carbonized wood and the co-occurrence of carbonized wood and siderite 
appears to be characteristic.

Another feature of the site is that it is located a short distance 
northwest of Mt. St. Helens and the sediments exposed along Salmon 
Creek contain a lot of volcanic material, including a couple ash 
layers. Late Miocene in age.

Some brief answers to Gary's questions:
- The feces were dropped into soft mud on a pond bottom and quickly 
replaced with siderite.
- There were a lot of animals at the site.
- Turtles.

Tom Yancey


>the salmon creek that i refered to is just outside of Toledo WA. Now that
>you brought it up i have questions about corpolite, how did it keep its
>form? why is there so much of it ? from its size it must have been a small
>critter, what kind of critters were they,
>
>----- Original Message -----
>From: "Charles Baran" <kcbaran at arczip.com>
>To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors"
><rockhounds at lists.drizzle.com>
>Sent: Wednesday, April 02, 2008 9:55 PM
>Subject: Re: [Rockhounds] salmon creek WA
>
>
>>  Are you talking about the Salmon Creek in Clark County, Vancouver
>>  Washington?
>>
>>  teresa jetter wrote:
>>
>>  >Hi Tim,
>>  >Where is salmon creek?
>>  >I have a girlfriend in sissonville, is it some place
>>  >close to her?
>>  >--- Tim Fisher <nospam at orerockon.com> wrote:
>>  >
>>  >
>  > >
>  > >>Quite a few people from NARG have been there
>>  >>already. I prefer to
>>  >>wait until the water is much lower and the stream is
>>  >>wadable. I don't
>>  >>think it has significantly changed. The channel is
>>  >>so incised that it
>>  >>would take a Biblical sized flood to leave any major
>>  >>obstacles.
>>  >>
>>  >>At 08:01 AM 3/24/2008, you wrote:
>>  >>
>>  >>
>>  >>>Can anyone tell me if digging at salmon creek at
>>  >>>
>>  >>>
>>  >>this time of year
>>  >>
>>  >>
>>  >>>is possible, especially after the flooding in the
>>  >>>
>>  >>>
>>  >>area this winter.
>>  >>
>>  >>Tim Fisher
>>  >>Ore-ROCK-On!
>>  >>Email address at http://OreRockOn.com
>>  >>
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-- 
Thomas Yancey