Let’s pick on a mineral for this blog.  A mineral that some people would not think is found in the area but the states of California and Alaska is known for.  All you have to do is mention “gold” and you will see their eyes light up.

Yes, indeed, gold is found in York County as well as throughout southeastern Pennsylvania.  If you would search historic geologic writings from as early as 1820, you will read that gold was reported from Chickies Rock in Lancaster County and several of the iron mines located on the southern slope of the Hellam Hills in Hellam Township.

In his classic report “Mineralogy of Pennsylvania” in 1920, Samuel Gordon mentions gold in York County, but does not disclose any specific location.

A green pan shows the black sand (magnetite) and gold better than a black pan

During the late 1960’s and well into the 1970’s, a group of well-educated mineral collectors would gather weekly for a trip to a “hot” mineral locality.  My father, Karl Jones, was a member of the group.  During one of their adventures, a member of the group mentioned that he would love to have a gold specimen from Pennsylvania.  Upon some research and talking with several geologists, the group identified some areas to investigate and the great search for gold started in 1973.

Gold is found in areas associated with igneous rocks and/or found in quartz veins  in rocks with magmatic origin or association.  With the largest exposures of volcanic rocks found in South Mountain in Adams, Franklin and Cumberland counties, the group searched long and hard for gold there.  They came up basically empty handed and puzzled.  Based on historical documentation and geology, they searched near Hunterstown, Adams County, and did find small flakes of gold.  The first find in this 1970’s gold rush.

A collection of gold flakes in black sand. Largest flake is ~1/8th inch

Peters Creek in southwestern Lancaster County became another target to search for the elusive mineral and yes, again, success was struck.  In fact, today, I consider Peters Creek the best gold panning stream in southeastern Pennsylvania.

The next move came into York County north of Delta where gold was found on the property of the Delta Fish and Game Club.  Their three tributaries flow into Muddy Creek which also hosts some gold toward the Susquehanna River.  Gold fever struck the members of the group and expanded their search area into other areas of York County.  Also, word began to reach the “rockhounding” world and other people learned the art of panning and made their own discoveries.

Panning is inexpensive. A shovel, pan, bucket and a sluice is all that is needed

Today, recreational panners can be found in area streams, hoping to win the lottery with a large flake or nugget.  The largest piece of gold I have personally seen was 0.75 inches.  This specimen came from a unnamed tributary to Muddy Creek near Castle Fin.  I regard this stream as the best gold-producing waterway in York County.  It was nicknamed “Lucky Creek” because of the results found by prospectors.   The stream may not contain the most gold, but this stream offers a natural setting for gold to accumulate.  Gold is the heaviest mineral known and will settle to the bottom of a stream over time.  In “Lucky Creek” the bedrock tilts into the Earth upstream.  This forms a natural ledge for heavy mineral to settle and prospecting is made slightly more simpler with the help of “Mother Nature.”

Other areas in York County include northern York County.  The very dense igneous rock known as diabase occupies much of this area.  It is known from other researchers work, that some Pennsylvania diabase contains gold.  My wife hates when I do this but I will bet my next paycheck that if you pan any stream in a quadrant bordered by Rossville and Wellsville on the south and Dillsburg and Grantham to the north, you will find a small flake of gold.  This even includes the popular winter hangout of Ski Roundtop in Warrington Township that is totally underlain with diabase.  Ask any unfortunate skier who has hit a rock coming down the slope just how hard the rock is.

Mentioned earlier in this blog was the mention of searching gold in South Mountain.  The same volcanic rock found in South mountain is also found in the Pigeon Hills near Abbottstown and the Hellam Hills in eastern York County.  Several streams pass through these rocks, but just like South Mountain, the streams appear to be void of gold.

Spring Valley County Park hosts the annual “Gold Panning” outing the last Saturday of July in Spring Valley Park.  The East Branch of the Codorus Creek contains gold that is washing out of the meta-igneous rocks in the area.  Although the flakes are barely large enough to be seen by our eyes, about 200 people attend the outing to learn the art of panning and maybe, just maybe, find a flake of gold.  Remember, being a county park, panning is not permitted other than the day of the event in July.

A mother and daughter try their luck at the gold panning outing

Was there ever any gold production taking place in York County?  As you may tell from the above description of gold in area streams, there appears not to be any “mother load” in York County.  However, there has been a story that has been passed up through generations in a family that a father and his two sons were making a profit prospecting for gold in the Airville area.  As the story goes, the one son thought he was being cheated out of his percentages and killed his father and brother, spending the remainder of his life in York County Prison.

It is a known fact that during the Great Depression of the 1930’s, gold miners who became unemployed from the mines along the Potomac River near Washington actually came into southern York County prospecting to have a small income.

In York County, gold has never been found in place (in bedrock).  All of the gold has been found in placer deposits in the streams.  The closest that gold has been found in place was from one of the slate quarries in Peach Bottom Township.  Here prospectors lifted up the bedrock, placed the loose rock in a gold pan and panned it,  finding small flakes.

Finally, remember to pan a stream you need to get permission from the landowner.  I even give the landowner a sample of the gold (if I find any) to the landowner.  They love to set a vial of gold on their shelf to try family members and friends.   GOOD LUCK!!!!

One of the most common questions I receive is “Were there ever volcanoes in York County?” After all, today we think of active volcanoes in the states of Hawaii, Alaska and Washington, as well as Iceland.

What you have to realize is that our part of the country has been through many changes over geologic time. One of the earliest geologic events that occurred here were volcanoes. Approximately 600 million years ago, we were not residing on dry land. York County was located on or near the boundary where an ancient continent known as Rodinia was splitting apart. This was similar to today’s mid-oceanic ridge, the longest mountain range on Earth, found in the Atlantic and Pacific oceans. Iceland, which made news early this year for its tremendous volcanic eruptions, is only the top of a volcano whose base lies some 30,000 feet under the Atlantic Ocean. Rodinia was also located well south of the equator.

Today, there are four areas where you could go to see volcanic rocks. A greenish rock that produces a dense sound when struck with a hammer is known as metabasalt. Today, basalt originates as lava on the ocean floor where two crustal plates are pulling apart.

Ancient sea-floor volcanic rocks can be seen at several areas in York County. The largest is at Accomac, Hellam Township. The large roadcut on the south side of Accomac Road near the Accomac Inn is composed of basalt. A similar rock can be seen in several roadcuts along Beaver Creek Road near the York-Adams County line in the Pigeon Hills. The metabasalt in the Pigeon Hills shows some cavities in the rock that were once gas bubbles in the lava.

Metabasalts along Accomac Road

Vuggy metabasalt along Beaver Creek Road

Basalt can also be observed along the York County Heritage Rail Trail between Glen Rock and New Freedom. The best location is found just north of a picnic rest area north of Taylor Hill Road in Shrewsbury Township. Here , similar to the basalt in the Pigeon Hills, you can find preserved gas bubbles. The fourth location and the most obscure is found adjacent to the Holtwood Dam spillway in Lower Chanceford Township. Here the basalt is similar in appearance with the surrounding rock known as schist. However, careful observation will show that the basalt is greenish in color and slightly more dense than the surrounding schists.

Metabasalt showing gas bubble cavities along the York County Heritage Rail Trail

Another volcanic rock in York County is known as rhyolite. Similar in composition to the more-famous rock known as granite, rhyolite is associated with the breakup of continental crust (remember basalt is associated with the rifting of oceanic crust). Since the rhyolite is about the same age as the basalt (about 600 million years old), this rock is directly associated with the splitting of the Rodinian continental crust. Rhyolite is present on the property of the Boy Scouts of America Wizard Ranch north of Accomac, Hellam Township. Rhyolite is also found at the southeastern corner of Rocky Ridge County Park in Hellam Township. The rock is a pale reddish or pink color and, like its sister, basalt, produces a dense ringing sound when struck with a hammer.

The rhyolite once was quarried as an ornamental stone just north of Highmount in the Hellam Hills. Although the quarry is no longer present, pieces of rhyolite can be seen scattered in the fields along Deer Forest Road.

If you read any geologic literature concerning our basalt and rhyolite, you will see “meta” placed in front of the words. Because our area has been through at least two major mountain building events (to be discussed in a future post), these rocks have gone through much heat, pressure and burial. As a result the mineralogy and/or texture of these volcanic rocks have changed.

Finally, you will be surprised to learn where the most volcanic rocks in Pennsylvania occurs. The oldest rocks in South Mountain of neighboring Adams, Franklin and Cumberland counties are metabasalts and rhyolites similar to the above mentioned. It is believed that South Mountain was a major rift of Rodinia about 600 million years ago.

How many of you have taken a walk either in a developed area or in the quiet woods and stumbled over an interesting-looking rock?  Have you ever wondered how the rock was formed or how it got here?  Interesting rocks can be found anywhere and all it takes is to reach over and pick it up.  Every rock has a story to tell and this blog will tell these stories.

Each day everyone comes in contact with both geology and history.  This blog will explore some of the most fascinating locations in York County. This column will introduce stories about the origin of some interesting rocks, how we use natural resources and how we live with our geology.  Related topics are certainly welcome from the readers.

What better place to start than to introduce you to the general layout of the land and rocks in the county.

The highest point in York County is Stone Head, high atop South Mountain west of Dillsburg.  This exposure of quartzite is at an elevation of 1,371 feet above sea level.

The lowest point is along the Susquehanna River at the Mason-Dixon Line at an elevation of 200 feet.  That means that York County has a total relief of 1,171 feet.  Because of its magnificent view, some people regard Same Lewis State Park as one of the highest points.  Actually, this location and elevations in the Pigeon Hills near Hanover and the Hellam Hills in the eastern section of the county are just over 800 feet above sea level.

In the northern part of the county, the steep-sided hills of Roundtop (Ski) and Nell’s Hill are elevations of 1,355 and 1,330 feet respectively.  The rolling hills of southern York County are generally 800-900 feet in elevation with one ridge near Airville capping off just over 1,000 feet.

York County hosts igneous, sedimentary and metamorphic rocks.  These rocks range in age from about 600 million years old to as recent as 150 million years. The southern third of the county is composed of mostly metamorphic rocks that tell us of a vast ocean and several continental collisions.

The historic U.S. Route 30 lies within a limestone valley from near Thomasville eastward into Lancaster County. The limestone and surrounding rocks on the bordering ridges reflect a breakup and construction of an ancient continent.  Proof of a beach can be seen in the rocks in the now abandoned York Silica Sand Co. quarry behind the Harley-Davidson plant.

The northern third of the county is underlain with sedimentary and igneous rocks that are the youngest in our area.  These rocks tell us the amazing story of when York County was an Everglades swamp followed by the breakup of a large continent known as Pangaea. It is hard to realize that over a course of one billion years, York  has seen several episodes of continental collisions and breakups, an ocean environment, volcanic activity and dinosaurs walking through the mud of an ancient swamp.  York County has it all in the eyes of a geologist and offers many adventures that will be included here.