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Subject: / Licking Creek Project Area
To: / Colleen Grundy, Silviculturist/Planner
Between July 23rd and July 27th, 2001 I investigated the Licking Creek Project proposed harvest units 10, 21, 33, 34, 35, 39, 40, small portion of 47, 64, 65, 66, 67, and 71. The purpose of the investigation was to verify the recently mapped geology of the Project Area, to determine if the areas are suitable for timber harvest, and to identify karst resources of concern given the proposed timber harvest.
Granite, phyllite, or marble (carbonate) or combinations thereof underlie the proposed harvest units in a general sense. I focused my inventory efforts within harvest units where carbonates were known to occur or recent geologic mapping suggested that carbonates may be present. Portions or all of proposed harvest units 10, 21, 33, 34, 35, 40, 47, 64, 65, 66, 67, and 71 were found to be underlain by carbonate. Karst drainages have developed, though sometimes limited, in all the carbonate blocks. Karst development seems to be limited in the “main” carbonate band, the band which underlies proposed harvest units 40, 64, 65, 66, 67, and 71. The undulating topography characteristic of a carbonate landscape is present but visible epikarst fractures and collapse features are not prevalent. It is possible that the carbonate of this band is somewhat dolomitized which has suppressed karst development. However, the carbonate band which underlies portions of proposed harvest units 21, 34, 35, 47, and 48 has developed very extensive karst and cave systems.
For this exercise it is necessary to roughly define how I applied the karst management standards and guidelines on the ground. Therefore, I will briefly describe my intent and application of the S&G's:
Low Vulnerability Karstlands: These are the carbonate areas most modified by glaciation, are highly weathered, or show limited karst development. These areas may be underlain by slightly dolomitic limestone or marble which can retard karst development. Within the Project Area they either occupy the lower third of the glacial valleys and generally have a deep (>40" deep) covering of glacial till and little or no epikarst showing at the surface or are atop the dolomitic marble. Often these were areas of gentler slopes (<40%). Any epikarst visible seemed to have formed after deglaciation on the outcrop scoured by the last glacial advance. Epikarst observed, tended to develop along bedding or foliation planes within the marble and/or along dike contacts. Surface drainages may be present
Moderate Vulnerability Karstlands: These are carbonate areas which were have a mosaic of shallow organic soils (20-40%, McGilvery Soils) and mineral soils (80-60%, Sarkar[<20" depth] and Ulloa [> 20" depth] Soils) with minor amounts of glacial till. The epikarst is moderate- to well-developed and is visible at the surface. These tend to be at higher elevations, i.e. on the upper two thirds of the valley slopes, and on knobs, ridges, and on the dip-slope of the bedding planes of the marble when near the surface. The epikarst valleys are filled or partially filled with residual soil and/or glacial till. Any epikarst visible seemed to have formed after deglaciation on
the outcrop scoured by the last glacial advance. Epikarst observed tended to develop along bedding or foliation planes within the marble, along the margins of phyllite interbeds and/or along dike contacts. On what is thought to be dolomitic marbles, small surface streams flow across less permeable beds, sometimes sinking for a short distance and continuing on the surface thereafter. Slopes of these areas vary from 20-70%. These lands posed little or no threat to organic, sediment, and debris introduction into the karst hydrologic systems beneath. Partial suspension was required on these lands to minimize soil disturbance.
High Vulnerability Karstlands: All collapsed karst features, caves, loosing streams and resurgences. The highest vulnerability features in my opinion, are those which could produce and transport the greatest amount of sediment if disturbed, are the till lined sinks and cave entrances accepting a loosing stream, whether intermittent or not, and the insurgent streams and features adjacent to the phyllite which produce very mobile sediment as they weather. Also considered high vulnerability are karstlands in which the epikarst was well- or extremely well-developed and the soils were predominately (>50%) very shallow organic (<10"deep, McGilvery) and (<50%) mineral (<20" deep, Sarkar). These karstlands, in my opinion, could move organics, sediments, and debris down, rapidly into the karst hydrologic systems beneath. I considered the entrance area surrounding resurgences to be of high vulnerability as to protect and maintain the environment surrounding the springs and the quality of the waters flowing from them. These areas tended to be at higher elevations except for the features found within one of the eastern most bands of carbonate at all elevations and slope positions.
For the most part the karst lands were low to moderate vulnerability having a combination of mineral and glacial soils atop them. The majority were of moderate vulnerability, with a limited amount (< 20%) of visible epikarst and the associated shallow organic soils. These areas had limited inclusions of high vulnerability, specific karst features. Most of the high vulnerability karstlands were contained within one of two discrete marble outcrops. Many of these take surface waters off of the adjacent phyllite bedrock. In my opinion, these have the most potential for adding sediment and debris into the karst groundwater system of any feature.
Harvest Unit 10
On 7/23/2001 Maurice Jones, Jim Wilds an I hiked into a reported karst feature adjacent to the northwest flowing stream in the western portion of the harvest unit. The feature was reported both by the layout foresters and Jackie deMontigny, soil scientist from Wrangell Range District. The majority of the proposed harvest unit is underlain by phyllite which strikes 314º and dips 48º to the south. Paralleling the eastern stream bank, just above the slope break of the v-notch containing the stream, is a band of marble approximately 20 feet in width. Within this band of marble are 6 collapse features, one small sinkhole and 5 vertical pits 10 to 30 feet in depth. Outside the harvest unit boundary and adjacent to the stream the water gathered by this karst system resurges from a small cave into the creek. The weathered phyllite bedrock is washing or failing into these karst features from the slopes above. While in the field we moved the existing slope break buffer which defines the unit boundary above the stream to include the karst features and a portion of the slope above them. However, after climbing up form the stream when we exited the unit I now believe that the unit boundary should be moved to the top of the cliffs above the karst features and the v-notch stream. The slopes exceed 90% and the soils at their base above the karst features are a mixture of weathered phyllite and colluvium off the cliffs. Given the steepness of the ground, I question the stability of the soils and colluvium on the slopes above the features and stream.
Prescription: The small band of marble containing the karst features lies at the base of a steep (90%) phyllite slope. The phyllite soils and colluvium above these features are have failed into several of the features. The slope break buffer for the stream was adjusted to the base of the cliffs above the features. In retrospect, I believe that the unit boundary should be pulled to the top edge of the cliffs to protect the karst features and stream below.
Harvest Unit 21
On July 26, 2001 I helicoptered to the alpine above proposed harvest units 21, 22, and 24 with Everett Kissinger and Pam Frohne. They moved down into proposed unit number 24 and I ridge walked to just above harvest unit 21. I wanted to prove or disprove my assumptions on our recent geologic mapping and walk the "interpreted" marble outcrop which runs through harvest unit 21. The marble band crossed the ridge where we had predicted. I entered the marble band at about 2,200 feet elevation. The karst development was intense with numerous sinkholes forming parallel to the bedding or foliation and/or along the fracture system perpendicular to the strike. This ridge top karst landscape also had the highest density of deer sign that I found during my week in the project area. I dropped down from the ridge crest following a creek flowing down one of the regional fractures from the phyllite to the marble. At about 2,000 feet elevation the creep abruptly turns and flows a short distance down the contact between the phyllite and marble then turns again an cascades into a karst feature 150' X 50'X 50' deep (Lat. 55º 33.034’, Long. 131º 17.314’ +/- 38’). Immediately adjacent to this feature is a collapse feature 150' X 200' X 60-80' deep (Lat. 55º 33.008’, Long. 131º 17.294’ +/- 38’). Close to these two features are many other very large collapse features. There are numerous possible entrances into the system below but I explored none since I was alone and lacking the technical equipment needed. The bedding/foliation of the marble band strikes 340ºand is vertically dipping. Following the strike of the marble down slope I found several other significant smaller features:
1. A vertical epikarst crack/cave entrance with a good stone rattle approximately 250’ down slope at and azimuth of 164ºfrom the second large collapse feature (Lat. 55º 32.972’, Long. 131º 17.300’ +/- 24’), location measuted approximately 40’ east of flagged feature.
2. An insurgence feature taking a small stream off the phyllite (Lat. 55º 32.941’, Long. 131º 17.256’ +/- 42’)
3. A couple of collapse features aligned along the bottom of a collapse channel trending 354º located southwest of #2 above.. The upper feature is an epikarst crack/cave entrace with a good stone rattle, the lower is an unexplored, straight walled collapse feature. The slope above the features is approx. 60% and 40% below (Lat. 55º 32.942’, Long. 131º 17.275’ +/- 42’).
Down slope and east of the above features I came across another stream coming in off the phyllite to the east entering a cliff bounded sinkhole. This seemed to be a limited insurgence
since the bottom of the collapse was silt filled and I could see a bathtub ring of needles. However I noticed the vegetation fluttering in the feature from a wind near the base of the cliff. I moved through the stink current in the sinks bottom to find a large pit entrance into the main cave system blowing cold air. The air was leaving the cave system with enough velocity to blow flagging held over the entrance straight upwards. Only extensive cave systems have this much
air movement. The bedding/foliation of the marble band strikes 340ºand is vertically dipping. The small stream off the phyllite enters the sink feature from an azmuth of 228º. The location of the feature containing the cave is Lat. 55º 32.885’, Long. 131º 17.284’ +/- 42’.
Further down the strike of the outcrop I found a 100' X 40' X 70' deep karst window into a large stream passage (30' x 30'), and another large insurgence collapse. These features were located on a bench between 60-70% slopes above and 50%+ slopes below. The bedding/foliation of the marble band strikes 335ºand is vertically dipping. The karst window is located at Lat. 55º 32.877’, Long. 131º 17.299’ +/- 190’. There is a large spruce tree adjacent to this feature, estimated 8 feet abh. The adjacent insurgence collapse is located at Lat. 55º 32.851’, Long. 131º 17.236’ +/- 76’. From the karst window, a small collapse valley continues down slope to the resurgnece for the whole system. At about 1200' elevation I found the resurgence cave, where the waters from the cave system flows from a cave passage into a 40-50' deep marble walled canyon cut into a 90-100% slope. There was a small passage just inside the insurgence, though wind was not exiting the system so the cave passage may sump upstream. The system resurgence is located at Lat. 55º 32.791’, Long. 131º 17.200’ +/- 76’. The bedding/foliation of the marble band strikes 333ºand is vertically dipping.
I followed the stike of the marble band down off the steep slopes and cliffs of the valley wall to the stream which trends to the west from the east at the slope’s base. Here I found where the stream cuts through the marble. There is an insurgence collapse adjacent to the stream. A gravel bar currently separates the stream from the feature who’s floor is some 4’ below the current stream’s bed. At higher flows the stream spills into the karst feature and some of the strams flow enters the karst system, most likely flowing towards Calamity Creek. The bedding/foliation of the marble band strikes 332º and is vertically dipping. This stream overflow insurgence is located at Lat. 55º 32.657’, Long. 131º 17.136’ +/- 27’.
Still following the strike of the marble band, I climbed and crossed over the knob which forms the southern lobe of proposed harvest unit 21. Much of this knob has bolwh down in the past and dense second growth timber now grows there. Not far from the streamside insurgence I located 2 large sinkholes (20’ dia., 12’ deep). A collapse depression continues from these sinks into the second growth where a few smaller sinks were located 50’ to the south and another estimated 200’ south of the GPS Location. The two large sinkholes are located at Lat. 55º 32.648’, Long. 131º 17.124’ +/- 26’.
I continued along strike of the marble until it intersected Calamity Creek. The marble is exposed in the creek’s bed at Lat. 55º 32.547’, Long. 131º 17.014’ +/- 45’. The bedding/foliation of the marble band strikes 8º and is dips 45º to the east.