I was going through some fall photos for a report I am working on and came across this sequence of mushroom pictures. This particular mushroom is a shaggy mane. Good to eat only when new and then it proceeds to turn into what looks like blobs of ink. The ink blobs are full of spores.
Observations of Washington State Landscapes, Geology, Geography, Ecology, History and Land Use
Thursday, December 30, 2010
Shaggy Mane Sequence
I was going through some fall photos for a report I am working on and came across this sequence of mushroom pictures. This particular mushroom is a shaggy mane. Good to eat only when new and then it proceeds to turn into what looks like blobs of ink. The ink blobs are full of spores.
Tuesday, December 28, 2010
Missoula Flood Routes in the Snow
Quincy Lakes Wildlife Area looking south with The Gorge further to the south and the Columbia River to the west (right). The diagonal line across the upper middle is Interstate-90.
I think I picked a good year not be traveling through London or New York at Christmas time. When I do fly I try to sit by the window. I suspect many geologists have sore necks from having their head turned to look out the window. I always enjoy trying to figure out where I am and what I am seeing.
I took the above picture on a recent flight from Seattle to Kansas City. The rain shadow effect had created a cloud free area over eastern Washington and I had this great view of the Quincy Lakes Wildlife Area with its deep Missoula Flood channels, dry water falls and flood gouged lakes above the Columbia River on the right side of the picture. This one of several flood routes that altered the eastern Washington landscape during the last ice age.
A smaller nick point on the right side to the south of the main channels is the site of The Gorge. The erosion by the spilling waters carved an amphitheater with great acoustics and great views. The site is used for large concerts in the summer. I'm fairly sure that the Dave Mathews Band has not done a Christmas concert here yet, but have paid several visits in the summer.
A little past the Gorge and Quincy Lakes Wildlife Area I got a view of yet another Missoula Flood Channel, The Winchester Wasteway and the North Columbia Basin Wildlife Area and the South Columbia Basin Wildlife Area. Water from the Columbia Basin Irrigation Project is routed through this natural drainage route carved by the Missoula Floods. The lakes and fresh water have developed into outstanding bird and fishing areas.
Winchester Wasteway looking south. The sharp straight line is Interstate-90
With the snow the channels were easy to see and trace. Much easier than figuring them out on the ground like Bretz did. A little further east before the clouds obscured my view I got a view of Moses Lake and Potholes Reservoir.
View looking south of mostly frozen Moses Lake crossed by Interstate-90 with Potholes Reservoir further south and not yet frozen
Wednesday, December 22, 2010
Wading for Geology
Shore of Discovery Bay
In the quest for greater scientific understanding one sometimes must get wet. I find it safer and much faster to wade than smashing through brush and tree limbs on slippery landslide surfaces. Besides this particular slide was covered with Nootka rose thickets. Given the choice yesterday, I went with wet legs versus brush wrestling and rose thorns.
Preglacial tidal sediments (?) possibly deposited during the advance of the Puget and Juan de Fuca ice lobes
Tuesday, December 21, 2010
Eclipse and Snow in Bellingham
The last couple of nights have brought a few small surprises. Sunday night we had a somewhat unexpected snow at roughly 2:00 am. Brightened up the night and early morning during our shortest days of the year.
And last night we were able to watch the eclipse. Given that it was cloudy all day yesterday and is cloudy again this morning it was an unexpected treat. I took the picture by sticking my camera lens into a binocular eye piece. Not exactly high quality optics and and hard to hold steady while taking the shot.
Sunday, December 19, 2010
Pushtay, an Odd Hill Near Selah, Washington
Pushtay on the eastern portion of the Yakima Firing Center
Topography map of Pushtay (note different name on the topo map)
A relatively small but odd hill is located east of Interstate-82 northeast of Selah, Washington on the U.S. Army's Yakima Firing Center. It is a bit hard to capture its out of place appearance. It is nearly a perfectly conical hill located on the south side of a broad slope of a large anticlinal ridge of the Yakima fold belt. The overall landscape of the area is broad sweeping valleys and ridges defined by the folded layers of basalt along with deep sharp edged canyons incised down through the folds. Hence this hill with its conical shape stands out as an oddity.
The base of the hill as well as the surrounding broad slope it rises from is underlain by the Pomona Member of the Saddle Mountains Basalt of the Columbia River Basalt Group. The Pomona basalt is approximately 12 million years old. Most of the hill itself consists of alluvial sediments that were deposited between eruptions of basalt during the upper Miocene. The particular unit on the hill is less than 12 million years old. Younger basalt lavas are present in eastern Washington; however, after the Pomona flows the volumes of later flows were substantially less voluminous. The only younger flows in the area that could have capped Pushtay is the Elephant Mountain basalt, but that flow is fairly thin in the area and may not have ever capped the alluvial sediments underlying Pushtay. The very peak area of the hill has been mapped as being underlain by Pliocene gravels that have been dated at 3.6 million years old.
The alluvial sediments that make up Pushtay were deposited by the ancestral Yakima River and perhaps also the Columbia River. The Yakima and the Columbia were pushed to the west by the repeated floods of basalt lava that filled the basin in eastern Washington. The river(s) likely was carrying a large sediment load from uplift and volcanic activity in the Cascade Range.
The Yakima River is an antecedent river. That is the river was there before the ridges formed. As south to north compression continued the Yakima fold belt lifted up the ridges that the river now cuts through. The meandering nature of the ancestal river is preserved where the river is entrenched into deeply incised valleys through the ridge areas particularly to the north of Selah in the Yakima Canyon - a classic example of entrenched meanders of an antecedent river.
Yakima Canyon topography with entrenched meander loop within Yakima Fold Belt ridges between Ellensburg and Selah
The antecedent nature of the Yakima River can be also readily be observed just north of Yakima and south of Yakima where both the river and Interstate-82 squeeze through Selah Gap north of Yakima and Union Gap south of Yakima.
Yakima River north and south of Yakima (Google maps)
The Yakima flows into the Columbia River. Not yet well understood changes in the area the Columbia River cuts through the Cascade Range likely caused an increase in gradient on the Yakima and thus increased the rate of down cutting by the Yakima further enhancing the entrenched nature of the current river. Possible changes on the Columbia River route through the Cascade Range may have been the result of volcanic activity.
Pushtay is a relatively isolated remnant of the old valley sediments from prior to the entrenchment of the Yakima. It is likely that the original remnant alluvial deposit that forms Pushtay was a somewhat different shape, but over the tens of thousands of years of frost action, wind and occasional sheet wash erosion from rare intense storms the hill was shaped into its current conical shape. Another factor to consider regarding the relative uniqueness of this hill is that similar features that may have once been present along the Yakima at lower elevations would have been obliterated by flood waters from the Missoula Floods that would have inundated areas below 1,200 feet. Pushtay at 1,845 feet as well the surrounding slopes would have been above the reach of the flood waters.
A look at the topographic map shows that Pushtay went by another name for many years. The name was changed to Pushtay after the Yakima Nation, Wanapum Tribe, and the U.S. Army made a request to the Board of Geographic Names for the name change in 1999. Pushtay means small mound in the local Yakima language. I have to admit the second part of the old name is descriptive and it may have been the first part that was more offensive.
Friday, December 17, 2010
Maury Island and Mining
North end of run ways at Seattle Tacoma Airport
While getting ready for takeoff I took this picture of the end of the run way at Seattle-Tacoma Airport. Big airports cover lots of ground and alter the landscape significantly. In the case of this airport lots of fill was required to extend the run ways over a low area at the north end of the runways. Bridges were constructed to support landing lights beyond the ends of the runway. But the changes to the landscape extend beyond the airport. All that fill has to come from somewhere and so the changes to the landscape take place elsewhere as well.
East shore of Maury Island
One source of sand and gravel is visible right after take off. The west shore of Maury Island has several mines. The mining takes place in glacial advance outwash, deposits of sand and gravel associated with melt water from the advancing glacial ice that pushed down into Puget Sound from the north. These deposits are particularly thick on Muary Island. Cal-Portland a Japanese owned concrete producer planned a major mine expansion on the island about ten years ago. The permitting process has taken a very long time primarily because the mine proposed using water access to ship via barge the mined aggregate. Without the ability to ship by water the value of the deposit is limited due to the low demand on Maury Island and Vashon Island (the two islands are actually attached via a narrow neck of land).
There are a variety of permits that are needed for any gravel mine, but water access and the construction of a pier involve more permitting than the mine itself. A variety of groups opposed the pier construction, but the mine obtained most of the permits until 2009 when a Federal Court judge ruled that the Army Corps of Engineers needed to do a more in depth analysis of the proposed pier and how noise and shading from construction and operation might harm orcas and chinook salmon, both of which are listed as endangered species. David Mann who recently argued a Freedom of Information case before the U.S. Supreme Court regarding another Washington Island was the attorney for groups appealing the Army Corps initial permit (see HERE)
After that decision the mining company became more receptive to selling the land and leaving the project. In April 2010 the Washington State Legislature approved $14.5 million for purchasing the land. King County Council approved $19.1 million dollars in November 2010 as well as a non monetary agreement worth $2.4 million regarding another mine site that is owned by the county but leased to the mining company. There is a commitment of $2 million by non profit groups to partially offset the County's purchase.
The State money comes from a settlement fund paid to the state by another mining company, ASARCO. ASRCO operated a smelter in Tacoma for many years and one legacy from that smelter is an area wide contamination of lead and arsenic from air borne deposition. One of the places most impacted by the smelter is the Maury Island and Vashon Island area, so there is a link between using the money at the location to offset the damages caused by the smelter. The County money is from a Conservation Tax, a property tax for purchasing properties for public open space. Many Washington Counties have such a fund. In King County the fund collection is bolstered by the high value of land in the most populous county in the state.
From a gravel mining perspective, this means that the value of other deposits that could serve the area or have an easier time accessing water will increase in value and demand. Gravel mining already takes place with water access south of Tacoma and a pit in Jefferson County near Hood Canal has proposed a conveyor system to load barges. There is a small rock quarry on Lummi Island in Whatcom County with water access and several mines in the straits between Vancouver Island and main land British Columbia. But other market factors also play a role. Some projects may not be constructed if the prce of aggragate gets too high or projects may be redesigned to use less aggregate or different materials.
At this point it looks like a new park with water access is in the works for the east shore of Maury Island. The geologic map that covers Maury Island (Booth, 1991) notes that the area of homes that can be seen on the photo above is modified land associated with mining. Post mining development is not uncommon. Shopping centers have been built in the old mines in Monroe and a residential development and championship golf course have been in development south of Tacoma in an area mined out.
Wednesday, December 15, 2010
A few geology views and a bit from that other Washington
I've been traveling. I am not a highly wired person so typically very limited posting when I travel. A few geology views and a bit from that other Washington. And I missed the big storms in western Washington.
Mount Rainier rises above the low clouds - classic view for air travelers out of or into Seattle. The small cloud cap on the summit is a frequent warning of bad weather on the way.
Missouri River and oxbow from valley wide channel migration approaching Kansas City
Great view in the other Washington.
I very much enjoyed the beer I had while sitting at this window.
And, yes, we had a great time
The southern end of a big glacial lake and the city of Chicago
Thursday, December 9, 2010
Orcas Chert on the Southwest Coast of San Juan Island
Orcas Chert on the west side of San Juan Island
Closeup of Orcas Chert
I always enjoy seeing the Orcas Chert. Orcas Chert of coarse is found on Orcas Island with extensive outcrops along the shores and steep slopes of East Sound and West Sound on Orcas. The formation also crops out along the the headlands on the west side of Shaw Island and makes up significant portions of the shoreline of the east, northwest and southwest sides of San Juan Island.
Orcas Chert is predominantly ribbon chert and has a great mangled look and with twisted geometry and unexpected surprises within the highly sheared rock. Chert is formed by the accumulation of silica bearing skeletons of organisms such as radiolaria, siliceous sponges and diatoms on the sea floor (see HERE for a view of a diatom deposit in eastern Washington). The silica bearing organisms sink to the bottom of the sea and accumulate enough to create silica rich layers. Chert formation typically requires low sediment input and thus are indicative of sites being far from land or at the least far from areas where much erosion is taking place. They are generally though of as being in deeper water as well or otherwise calcium carbonate bearing shells or corral would predominate. So the presence of chert gives a hint as to the source environment - ocean floor possibly deep water or far from an eroding land mass.
The Orcas Chert consists primarily of ribbon chert consisting of alternating chert layers with thin layers of shale. The shale consisting of metamorposed mud stone. Orcas Chert also includes lesser amounts of pillow basalts (lava that erupted under water), volcanic tuff and limestone. The limestone is interesting - more on that later.
The Orcas Chert is part of a suite of rocks belonging to the Northwest Cascades System (NWCS). The NWCS is not a simple assemblage and taking a walk along the the Orcas Chert exposed on the west side of San Juan Island is a good reminder. Lappen (2000) assembled the Geologic Map of the Bellingham 1:100,000 Quadrangle that includes much of the San Juan Islands. The accompanying report provides only a brief description of the geologic setting but I think it sums up the NWCS rather well as "This structural system is a thrust stack of mainly oceanic lithologic packages (terranes) of varying age, structure and metamorphic history." I would emphasize "varying" as an understatement. When I get asked about these rocks or other assemblages of metamorphic rocks in the San Juans or Northwest Cascades I often say these rocks have had a long hard life.
The west side of San Juan Island parallels one of the many thrust faults that juxtapose formations within the NWCS. This fault juxtaposes the Orcas Chert with the Constitution Formation to the east. But it is within the Orcas Chert that one can get some sense of how complicated the NWCS is.
Highly sheared Orcas Chert with fragments of green and possible blue schist
While the NWCS can be described as a melange (French for mix) belt, the Orcas Chert could be described as a melange within the melange. Within the outcrops along the west coast of San Juan Island there are number of highly deformed zones with fragments of other formations embedded withing the sheared Orcas Chert. Its a great place to exercises your ability to determine shear direction and metamorphic fabrics. I take some comfort in that sense of shear has been variously interpreted in these rocks. One thing is clear - these rocks have gone through multiple tectonic events during there journey from the quiet ocean floor sediment basin to being accreted onto the North American Continent and then further faulting and crunching.
Orcas Chert with fragments of limestone
Fossil radiolari in the less mangled chert indicate that the chert is Jurassic to Triassic in age. However, fossil fusulinds within the limestone within the Orcas Chert are Permian. More evidence of the hard life these rocks have had since deposition on the ocean floor. The west coast of San Juan Island is a rare place to see continuous rock outcrops in the low lands of western Washington. Not an unpleasant place to contemplate complex metamorphic and tectonic questions. And there are plenty of other landscape features on this coast as well.
Southwest coast of San Juan Island
Tuesday, December 7, 2010
San Juan Island Rum Runner
Old boat above a small inlet on the west shore of San Juan Island.
The south end of Vancouver Island across Haro Strait is in the distance
While visiting the west shore of San Juan Island I observed an old steel boat hauled up out of a small harbor. Locals knowledgeable about the boat told me it had been used for running rum during prohibition. The west shore of San Juan Island is approximately nine miles from Victoria, British Columbia, Canada located across Haro Strait. Islanders had been used to relatively free trade between United States Territory and British Territory during the years that the San Juan Islands were in dispute between the two countries. The Oregon Treaty of 1846 had set the border between U.S. and British territory as the 49th parallel. However, control over the San Juan Islands was not settled until 1872.
Once the United States assumed full official control of the islands a long tradition of smuggling across Haro Strait began almost immediately with shipments of woolens and silk. At that time Victoria was the big city and most goods were moved via water as few roads existed on the mainland. Smuggling operations would ship goods through the multiple passages of the islands and then to points south such as Seattle, Port Townsend, and Tacoma. Besides avoiding duty prohibited cargo included opium into the United States for migrant Chinese workers as well as Chinese workers themselves. Prohibition of alcohol in the United States from 1919 to 1933 lead to very lucrative shipping during that time period. While buried Spanish gold have intrigued island visitors, a lost stash of well aged single malt has an appeal as well. Of course smuggling still goes on with cocaine and marijuana still shipped through the islands. This past year a Canadian boat was abandoned on the shore of San Juan Island and was suspected to have been used to transport goods otherwise not allowed in the United States.
Monday, December 6, 2010
Side Trip to Mount Constitution, Orcas Island
My work day last Friday was tough to beat. A project on the west shore of San Juan Island and then a short visit to a site on Orcas Island. The downside to work trips to the San Juan Islands is coordinating ferry times or flight times. On Friday I drove and took the ferry and the timing worked out well.
The timing of the ferry from Orcas back to Anacortes (mainland) left me about 3 hours to spend on the island as my Orcas project took little field time. I headed up Mount Constitution on the northeast side of the island. The road was clear to the high plateau at 2,000 feet was clear. The gate just past the switchbacks on the south side of the mountain was closed as beyond that the road to the summit was ice and snow covered. I made the hike to the summit past the still frozen Summit Lake and enjoyed the classic views from the summit including one toward my current home town.
Weaving through the San Juan Islands from San Juan Island to Orcas Island
The timing of the ferry from Orcas back to Anacortes (mainland) left me about 3 hours to spend on the island as my Orcas project took little field time. I headed up Mount Constitution on the northeast side of the island. The road was clear to the high plateau at 2,000 feet was clear. The gate just past the switchbacks on the south side of the mountain was closed as beyond that the road to the summit was ice and snow covered. I made the hike to the summit past the still frozen Summit Lake and enjoyed the classic views from the summit including one toward my current home town.
Summit Lake on Orcas Island
Barnes Island and Clark Island in Rosario Strait, Lummi Island,
Hale Passage, Bellingham Bay, Bellingham and Mount Baker
Sucia Island - a southwest plunging syncline off of Orcas' north shore
View across Strait of Georgia to Sandy Point and Cherry Point
Not a bad day at all. Mount Constitution is within the 5,000 acre plus Moran State Park. It is an amazing piece of wild mountain terrain with lakes and cliffs high above the Salish Sea. Moran was a ship builder who retired to Orcas Island in the early 1900s. He bought the mountain and offered the land to Washington State in 1911. The State initially turned down the offer! It took 10 years to convince the powers in State government to accept the offer. The site is now one of Washington State's premier State Parks. Moran's vision to share the pleasure and rest that this area provided him was greatly enjoyed this last Friday by a geologist killing some time between ferry rides.
Thursday, December 2, 2010
Indian Island U.S. Supreme Court Case
An issue related to Indian Island south of Port Townsend was taken up by the United States Supreme Court yesterday. I previously did a short post on Indian Island HERE. As noted nearly the entirety of Indian Island is owned by the Navy. A loading facility is located approximately two miles across the water from the City of Port Townsend and residences on Marrowstone Island are less than one mile from Indian Island.
The issue was a public information request by Glenn Scott Milner for a map showing the Explosive Safety Quantity Distance for the Naval Weapons Depot on Indian Island. The Navy declined to provide him the map citing an exemption in the law. Mr. Milner claims that exemption is being misapplied.
Congress did allow exemptions from public information requests and the issue is whether or not the denial by the Navy meets the exemption Congress provided. The Navy could have classified the map, but did not. In fact they gave the map to the local emergency responders. It is a good idea for local emergency responders to know just what sort of materials might be present in case of a fire or other emergency (see more below). Because the map was not classified, local responders provided the map to the newspapers. But the concern is that operations could change and the public may be unaware of the risk posed by the weapons depot.
The issue has moved up through the Federal Court system until it was argued before the U.S. Supreme Court yesterday. Dave Mann argued the case for Mr. Milner and numerous media interests had filed supporting arguments as the media tends to like open transparent government. I will note I had the pleasure of once working with Mr. Mann as an expert witness on a case.
I did find a few gems in the transcript of the oral arguments.
Judge Beyer stated "They want firemen to have then (the maps), but they do not want people who might blow them up to have them."
Of course this could be turned into "They don't want people that might be blown up to have them (the maps)."
Mr. Mann responded with "We are talking about public waterways, private land around the base and whether or not that land stays secure." In this regard Mr. Mann raises how this issue can impact the landscape.
A number of industries are required to provide hazard maps associated with explosive or dangerous materials stored or used on their sites. I do know that these industries do not always like putting these maps out and they note concerns about being terrorist targets if terrorists know the damage a release or explosion at the plant may cause.
Locating facilities that have highly explosive materials or toxic chemicals away from population centers is one means of reducing risk. And avoiding locating homes near such facilities is the other half of reducing the risk. A large oil refinery in Whatcom County has purchased significant swaths of land around the refinery to limit development from being located within potential danger areas. This approach has protected significant wildlife habitat that would otherwise not have been protected.
Loading crane at Navy weapons depot facility on Indian Island can be seen from
this view from Tamanowas Rock east of Chimacum.
The issue was a public information request by Glenn Scott Milner for a map showing the Explosive Safety Quantity Distance for the Naval Weapons Depot on Indian Island. The Navy declined to provide him the map citing an exemption in the law. Mr. Milner claims that exemption is being misapplied.
Congress did allow exemptions from public information requests and the issue is whether or not the denial by the Navy meets the exemption Congress provided. The Navy could have classified the map, but did not. In fact they gave the map to the local emergency responders. It is a good idea for local emergency responders to know just what sort of materials might be present in case of a fire or other emergency (see more below). Because the map was not classified, local responders provided the map to the newspapers. But the concern is that operations could change and the public may be unaware of the risk posed by the weapons depot.
The issue has moved up through the Federal Court system until it was argued before the U.S. Supreme Court yesterday. Dave Mann argued the case for Mr. Milner and numerous media interests had filed supporting arguments as the media tends to like open transparent government. I will note I had the pleasure of once working with Mr. Mann as an expert witness on a case.
I did find a few gems in the transcript of the oral arguments.
Judge Beyer stated "They want firemen to have then (the maps), but they do not want people who might blow them up to have them."
Of course this could be turned into "They don't want people that might be blown up to have them (the maps)."
Mr. Mann responded with "We are talking about public waterways, private land around the base and whether or not that land stays secure." In this regard Mr. Mann raises how this issue can impact the landscape.
A number of industries are required to provide hazard maps associated with explosive or dangerous materials stored or used on their sites. I do know that these industries do not always like putting these maps out and they note concerns about being terrorist targets if terrorists know the damage a release or explosion at the plant may cause.
Locating facilities that have highly explosive materials or toxic chemicals away from population centers is one means of reducing risk. And avoiding locating homes near such facilities is the other half of reducing the risk. A large oil refinery in Whatcom County has purchased significant swaths of land around the refinery to limit development from being located within potential danger areas. This approach has protected significant wildlife habitat that would otherwise not have been protected.
Wednesday, December 1, 2010
Pronghorns in Eastern Washington
Pronghorn (Image from Wikipedia)
I have a clear memory of our family encyclopedia with the a great chart showing animals running speed. Cheetahs were the fastest on the chart with the pronghorn of North America second. Cheetahs can reach 70 mph and pronghorns clock in at 60. But pronghorns can maintain high speeds for long distance and for that I always admired them. The same chart showed that a top human marathoner could out run all animals with one exception - the pronghorn. Being a long distance runner I have always been a great admirer of the pronghorn.
A few years ago while traversing an alluvial fan in Nevada on foot in a snow storm I surprised a pronghorn that was in the incised stream channel. Being within 25 feet of a pronghorn that bolts was a thrill. It put hundreds of feet between us in seconds. After a minute of running it stopped and turned to look back at me. I realized it was at least 3/4 of a mile away! I was no match. Nor would any known predator match the running of a pronghorn.
Significant portions of eastern Washington look a lot like Nevada and eastern Oregon. In fact pronghorn preserves are located in southeastern Oregon and northern Nevada. While we have wild horses like Nevada on the scrub steppe (HERE), there are no pronghorns in Washington State. This question has perplexed me as well as a number of biologists.
Pronghorns used to live in eastern Washington. Lyman (2007) provides an excellent summary of the information that has accumulated regarding pronghorn from archaeological sites. Based on the archaeological record, pronghorn lived in eastern Washington throughout most of the last 10,000 years and were a food source for First Nations people; however, they were never as abundant as elsewhere in their range and eastern Washington was likely marginal habitat with limited connectivity to other pronghorn habitat. Pronghorns appear to have disappeared in eastern Washington prior to the Lewis and Clark Expedition and other explorations into eastern Washington as there are no unambiguous documented pronghorn observations. Bison were similar to pronghorn in that they were formerly in eastern Washington in numbers less than elsewhere in their range.
While hunting likely impacted pronghorn and bison populations, there were plenty of pronghorn and bison east of the Rocky Mountains well through the mid 1800s. Hence, other factors likely played a role besides hunting by First Nations peoples given that northern plains peoples were highly dependent on hunting.
Lyman (2007) and Lyman and Wolverton (2002) suggests a combination of forage quality, migration obstacles and human predation limited pronghorn and bison populations in eastern Washington. Williams (1987) suggests water content of snow played a factor.
Pronghorns prefer forb plants over grass. Grassier areas of eastern Washington hence would limit pronghorn range. In addition, eastern Washington is very dry in the summer so nutrient values, particularly protein in forage are lower during critical summer months while mothers need milk for young. Access to water would also be a limiting factor for pronghorns in eastern Washington. Deep long lasting snow also poses a problem for pronghorns particularly in areas where forb plants are low growing. A deep snow winter is not uncommon in significant parts of eastern Washington and in areas with generally low snow, one bad year would devastate the population.
Migration corridors between eastern Washington and other pronghorn habitat areas is very restricted. The limited scrub steppe and grass lands of eastern Washington are relatively isolated from other pronghorn areas. Pronghorn habitat in eastern Oregon is continuous with vast tracts of similar habitat in Nevada and Idaho and points beyond. But the Oregon range is separated from eastern Washington by the Blue Mountains and other high forested areas between the Blues and the Cascade Ranges with only a relatively narrow area of suitable habitat connecting the two areas. The very large Columbia River and Snake River as well as a few other rivers also present a significant barrier to in migration. The limited migration would play a role if numbers declined due to any number of factors. One very bad winter with deep wet snow even if rare would be take a long time for population recovery due to the limited migration routes.
Regardless of the natural challenges facing pronghorns in eastern Washington, pronghorns were apparently present throughout the past 10,000 years up until just before the first American and fur trading explorers arrived in the early 1800s. The predator-prey balance with humans may well have been tilted against pronghorns when eastern Washington First Nations obtained horses in the 1700s. The fact that pronghorns were present in eastern Washington for 10,000 years until they disappeared when they did certainly implies some change had taken place. Perhaps a marginal population could not survive the added pressure of hunters on horse back.
I would propose another factor to be added to the forage, migration and snow factors - the local geology and topography. Eastern Washington would be full of potential hunting traps to drive pronghorns toward. Large rivers and cliffs in the scab lands would provide excellent drive locations for hunting relative to other areas where humans and pronghorns interacted. Add the use of horses and perhaps the human predation would have been just enough to finish off the already low pronghorn numbers.
Given our current impacts on the landscape, it is extremely unlikely that pronghorns will ever return to eastern Washington on their own. For one thing, despite their amazing running ability they go under or through fences as the are lousy jumpers. Pronghorns were introduced as a game animal to eastern Washington in the early 1900s, but the population did not survive. Some First Nations groups are considering pronghorn introduction. Perhaps portions of The Yakima Nation Reservation would support pronghorns or the Hanford Reach National Wilderness Area in combination with the adjoining Saddle Mountain National Wildlife Area, Hanford Nuclear Reserve and the Yakima Firing Range or the public lands of the Telford scabland area. I for one would love to see pronghorns eyeing the cars crossing through the Hanford area or on the high ridges between Yakima and Ellensburg.
Further Reading:
Lyman and Wolverton, 2002, The Late Prehistoric Early Historic Game Sink in the Northwestern United States, Conservation Biology.
Lyman, 2007, The Holocene History of Pronghorn (Antilocapra americana) in Eastern Washington State, Northwest Science.
Williams, 2005, Spatial Precipitation Variability, Snowfall and Historical Bison Occurrence in the Northwestern United States, Anthropology Theses Georgia State University.