navi
starting to spend too much on rocks
Member since November 2008
Posts: 229
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Post by navi on Mar 6, 2009 17:11:55 GMT -5
I don't understand this. The Meremac river by my house has river tumbled agates, from south and west of here. I have several spots I go to.
So, today I was walking on a trail with my sons and found a new beach on the same river, maybe 4 miles upstream of my favorite spot. The shore was a huge beach, entirely covered in small rocks!!! I thought I was at the motherload.
Not a single agate.
It's the same river, pulling from the same sources. The rocks I find farther downstream all came past here.
What gives? How is this possible?
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Post by sitnwrap on Mar 6, 2009 17:21:08 GMT -5
Could they have trucked in the sand/pebbles to make the new beach.
I walk a local ocean beach and they have done that with different sections of that beach frome time to time. I hate when they do it and it's a waste of money cause the tides just disperse it anyway.
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agatemaggot
Cave Dweller 
Member since August 2006
Posts: 2,195
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Post by agatemaggot on Mar 6, 2009 18:41:08 GMT -5
I may be mistaken but I think that agate may be harder and denser then most other rock. The current may have been stronger or straighter / faster on your (favorite ) stretch of river and slower on the new area. The faster current may have carried away the lighter stones from your favorite beach and left the agate exposed. The new area may have a slower current that has been depositing the lighter material over the top of the heavier Agate which may be there but deeper in the deposit.
I have noticed this type of thing going on in the Sand plants we hunt for Lakers. The classified stone falls from a moving belt 10 or 12 foot above a built up pile that may be 8 to 10 ft. high. An Agate and another type of stone the same size will behave differently. A piece of Granite may fall on the top of the pile and after hitting it may bounce and slide about halfway down the pile. An Agate on the other hand seems to have more Kinetic energy built up because of it's density and weight to size and more often than not, it will bounce and slide to the bottom or all the way down and roll away from the main pile several foot. When we hunt sand plants we always start looking about 6 foot from the base of the pile and work our way inward until we reach the base .
If your new beach is covered with smaller pebbles there might well be Agate there but you might need a rake to get em !
This is only a half-A$$ theory I have conjured up during my many wanderings so, don't quote me as there is no reason why 2 of us should sound like Dufuses. I am sure that someone on our Forum is up to speed on the weight to mass thing and would be able to explain to us what the heck I was trying to say here !
Harley
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navi
starting to spend too much on rocks
Member since November 2008
Posts: 229
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Post by navi on Mar 6, 2009 20:29:10 GMT -5
so, when the mrs. got home, i got to sneak out and spend about 30 minutes at my good spot. now, this was my 3rd time there this week and spent about 30 min there each time. each time, including today, i left with at least 5 pounds of banded lace agate, ranging from quarter to softball size. i actually got some real nice ones today shaped and ready, just about, for fine grind.
so i started thinking, what's different about this spot?
it is barely, just barely on the inside of a bend (small bend) and at the start of it. the earlier location today was on a mostly straight stretch.
regardless, i know where my good spot is!!! :-)
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agatemaggot
Cave Dweller
Member since August 2006
Posts: 2,195
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Post by agatemaggot on Mar 6, 2009 20:38:01 GMT -5
We may be on to something here, Gold as it travels downstream tends to gather in the same type of place if I remember right. You might be able to find a topographic map of the area and get a birds eye view showing the hot spots !
Harley
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Mar 6, 2009 20:57:24 GMT -5
Could be a river-sorting thing as already mentioned. Could also be that there are other rockhounds in your area, and your new beach is their favorite beach!!
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franzibear
starting to spend too much on rocks
Let's rock
Member since October 2008
Posts: 139
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Post by franzibear on Mar 7, 2009 12:55:10 GMT -5
I think I'm with rollingstone on this one. It seems that even accounting for river-filtering according to density and weight, there should still be SOME agates at the new beach, if perhaps somewhat smaller and at a different part of the beach... That's my thinking at least. Truly, there's nothing new under the sun. If it's such a promising beach, then it, or the river upstream of it, may have been picked over pretty well. OR, perhaps, the source of the agates you find downstream comes from a concentration somewhere below the new beach..... Or it's simply the law of diminishing returns....
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