San Juan Islands Geography

The San Juan Islands watershed (HUC 17110003) encompasses 592 square miles.1 It is bordered to the east by the Strait of Georgia watershed. It is bordered on the south by the Puget Sound watershed. The watershed includes all of San Juan County. There is no principal urban area, although Friday Harbor is the county seat. No tribes are located in the watershed, although it is part of the Usual and Accustomed fishing area of the Lummi, Swinomish, Upper Skagit, Nooksack, and Tulalip tribes.

USGS Cataloging Unit: 17110003 (click image for detailed view)

Descriptions of the main islands within the San Juan Islands watershed follow:2

Barnes Island

Barnes Island is located about one and three-fourths miles from the northeast shore of Orcas Island, opposite Mount Pickett. It has a length of 1000 yards and a maximum width of 280 yards, with an area of 36.1 acres. It is elongated parallel to the strike of the rock formations. The surface of Barnes Island is wooded and quite flat and contains a thin covering of glacial drift in many places. The maximum elevation on Barnes Island is about 40 feet.

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Blakely Island

Blakely Island is located on the east side of Lopez Sound. The waters of Thatcher Pass separate it from Decatur Island on the south. On the east the waters of Rosario Strait bound it. The narrow waters of Peavine Pass separate it from Obstruction Island on the north.

Blakely Island has an area of 6.93 square miles. With the exception of a fringe of glacial materials that occur as a bench about 90 feet high along the northwest side, and an occasional remnant of glacial material near the southern end of the island, the region is rocky and mountainous and the shorelines are precipitous. Blakely Dome, the highest elevation on the island, occurs near the northeast margin with an altitude of 1060 feet. Near the shore at the eastern extremity of the island a hill rises to an elevation of 780 feet. This hill is connected with Blakely Dome by an elevated ridge that forms the shoreline in this vicinity.

The southern extremity of Blakely Island is formed by a small hill that rises to an elevation of 260 feet. This hill is elongated in a northwest and southeast direction and a thick bench of glacial drift flanks its southern margin.

To the north of Thatcher Harbor there is a precipitous mountain known as Bald Bluff, which is elongated in a northeast and southwest direction.

Bald Bluff rises to an elevation of 880 feet and its western sides are deeply striated and polished by glacial action. Along the north shore of Thatcher Harbor a thick bench of glacial drift flanks its sides.

Each of the dome-shaped mountain peaks that occur near the shore of Blakely Island slopes gradually towards the center of the island. In the central depression there are two large lakes. The northern or upper lake is known as Blakely Lake, and its elevation is 374 feet. The lower one, which is known as Thatcher Lake, has an elevation of 188 feet and drains directly into Thatcher Harbor.

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Cactus Islands

Cactus Islands are located about midway between Ripple Island on the north and Spieden Island on the south, being separated from the latter by New Channel.

The western or smaller island has an area of 8.7 acres and its flat surface has a maximum elevation of about 40 feet.

The eastern island has an area of 22.7 acres and its maximum elevation is 60 feet. The south sides of both Cactus Islands trend about N 65° W, or parallel to the strike of the rock formations. The shorelines are steep, being quite straight and smooth when running parallel to the strike of the rock formations, and jagged when crossing the strata.

Near the southeast end of the larger Cactus Island there are two small rocky islands that are connected to it by a submerged reef. A reef occurs along the south shore of the same island.

The Cactus Islands are both wooded but the soil covering is scarce.

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Clark Island

Clark Island, with an area of 55.05 acres, is located about 625 yards to the east of Barnes Island. It is about a mile long and its maximum width is about 300 yards. The northern part of the island trends in the direction of the strike of the rock formations, but the southern portion is formed largely of glacial drift that connects with another rocky ridge at the southeastern extremity of the island. Clark Island has a maximum elevation of about 50 feet and its flat drift-covered surface is heavily wooded.

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Decatur Island

Decatur Island is situated on the east side of Lopez Sound. The narrow waters of Lopez Pass separate it from Lopez Island to the south. On the east the waters of Rosario Strait bound it. The waters of Thatcher Pass separate it from Blakely Island to the north.

Decatur Island has an area of 3.58 square miles. It is roughly triangular in shape, the north side being relatively straight while the other two sides converge into a long narrow arm that extends toward the south.

The northeast corner of Decatur Island projects toward the east, parallel to the strike of the rock formations, to form Fauntleroy Point. About a mile to the south, along the east shore, a long elevated double sand spit extends out to connect with a dome-shaped rocky land mass 200 feet high. This dome-shaped rocky point is known as Decatur Head. The east side of the island from Fauntleroy Point southward is deeply covered with glacial drift. To the southwest of Decatur Head the cliffs of glacial drift rise to elevations of 180 feet. Farther southward the land slopes gently until it is only a few feet above high tide-level.

Along the west side of Decatur Island there is a dome-shaped rocky land mass that rises to an elevation of 160 feet. It is connected with the main portion of Decatur Island by a recently elevated double sand bar, and the lagoon that formerly existed between them has been filled with rocky debris. To the southeast the shoreline is formed by cliffs of glacial drift, with occasional outcrops of bedrock at the northern portion. Large glacial erratics together with many smaller boulders are scattered along this shore.

The northern and northwestern parts of Decatur Island are high and rocky. The maximum elevation on the island, which is located in the northwestern portion, is 540 feet. The northern part of the island is very heavily wooded.

A mountain spur extends southward towards the southwest shore of the island near Decatur post office. To the south of Decatur post office the elevations are low and the land is deeply covered with glacial drift. The curved shoreline to the south of Decatur post office is sometimes spoken of as the Macedonian Crescent.

The south end of Decatur Island is formed by an elevated and elongated rocky hill that rises to an altitude of 140 feet. To the west at a distance of about 100 yards there is a dome-shaped hill with an elevation of 120 feet. This is connected with Decatur Island by means of a long sand bar that has been built above the level of high tide. Near the north side of this sand bar there is another and much smaller rocky island.

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Henry Island

Henry Island has an area of 1.59 square miles. It is located at the northwest end of San Juan Island, being separated from it by the narrow shallow waters of Mosquito Pass.

The island is composed of two curved parallel ridges that trend at about N 25° E. The convex sides of the curved ridges face towards the northwest. The outer or northwestern ridge is about three miles long and its average width is about 1000 yards. The other ridge is located about 500 yards to the southeast. It is about one and one-half miles long with an average width of 500 yards. The southwestern extremities of the two ridges are located at points nearly opposite each other, but owing to its greater length the outer ridge extends much farther northeastward than the other.

The longitudinal depression between the two ridges is filled with salt water except near the center of the shorter ridge, where a low sand bar connects the two ridges. Henry Island consequently has the general shape of the letter H.

The water entering the longitudinal depression from the south is known as Open Bay. It has a depth of approximately 500 feet at its entrance, but the depth decreases rapidly as the inner half of the bay is less than 30 feet deep. The deepest part of Open Bay is found near the western part of the entrance.

To the north of the connecting sand bar the land is swampy for a distance of several hundred feet. The remainder of the depression is filled with shallow water entering from the northeast. This shallow body of water, which is little more than six feet deep at low tide, is known as Nelson Bay.

The inner ridge is rocky at each end, with elevations up to 100 feet at the southern end, and up to 60 feet at the northern end. The central part of this ridge is low and covered with glacial drift. A large part of the higher portions of the ridge is thinly drift-covered.

The southern half of the western ridge is rocky with elevations up to 355 feet. At the extreme southern end of this ridge there is a hill 310 feet high, with precipitous sides that extend down into very deep water. This hill is known as Kelletts Bluff.

The shores along the west side of Henry Island are steep and precipitous. The southern half of this shoreline is rocky, while the northern part is chiefly sandy and less elevated. The exceedingly deep waters of Haro Strait bound Henry Island on the west.

The central part of the western ridge slopes gently down towards the shores of Nelson Bay. This area is largely drift-covered. A rocky peninsula rising to an elevation of 60 feet extends eastwardly near the entrance of Nelson Bay. To the north of this peninsula the eastern shores are precipitous and elevations up to 200 feet may be found.

The northern end of the island is low and drift-covered with occasional rocky knobs outcropping at the shoreline. A large part of Henry Island is covered with conifers and other trees and shrubs.

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Johns Island

Johns Island, with an area of 214.55 acres, is located to the east of Stuart Island and separated from it by the narrow waters of Johns Pass. Johns Island is elongated parallel to the strike of the rock formations or about N. 600 W. It is about one and one-half miles long and its maximum width is 650 yards. The northern side of Johns Island is elevated and rocky with steep and rugged shorelines. It is penetrated by two small harbors that cut across the elevated resistant formation. The south side of the island is largely drift covered with an occasional rock outcrop near the water's edge. An elevated wave-built sand bar forms a portion of the southern shoreline and a swampy area occurs behind it. The glacial drift occurring along the southern shore has been deposited on the glacially truncated and polished surfaces of the underlying rock formations. Johns Island is heavily wooded in some parts, while in others the vegetation is very scanty. A small reef occurs about 175 yards from the south shore opposite the central part of Johns Island.

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Lopez Island

Lopez is easily the most suitable of the islands for agriculture, as water is readily accessible on most parts of the island. The soil is good and the island is fairly level, more so than any of the other large islands in the archipelago. In former years, when it was possible to farm for profit, many prosperous, well-kept farms were operated here. Fruit trees thrive phenomenally. In 1900 one six-year-old orchard produced 300 boxes of apples, half a ton of cherries, 1500 pounds of prunes, half a ton of plums, and 40 cases of strawberries. The island got its own creamery in 1908 and was sending 1500 pounds of butter a month to Seattle, Bellingham, and Anacortes.

The fishing industry was also in high gear during the early part of the last century. In an average season forty or fifty outfits, employing more than 400 men, filled the entire bay off the southern coast of Lopez and took a million fish. Most of this activity was centered around Richardson Bay. The town was named for George Richardson who settled there in 1871.

Lopez Island has an area of 29.45 square miles. It is less mountainous that Orcas or San Juan Island, the surface being typically flat or gently undulating and covered with glacial drift. The southeast portion of Lopez Island is more rugged than the remainder, and the shoreline is broken by a complicated group of harbors.

At the north end of Lopez Island there are two elevated rocky masses that extend out from the shore as long parallel ridges trending north and south. These rocky masses are, in reality, islands that have been tied to the main part of Lopez Island by broad arms of glacial drift and alluvium.

The western mass, which is known as Upright Head, is about a mile long and 600 yards wide. The west side rises precipitously to an elevation of 260 feet, but the eastern slopes are more gentle and they approximate the dip-slopes of the rock formations. Upright Head is heavily wooded.

The eastern shoreline of Lopez Island is somewhat more broken than the western one. To the south of Humphreys Head a broad shallow bay known as Swifts Bay opens out towards the northeast. Along the east shore of the island south of Swifts Bay two long sand spits extend towards the east and converge to a sharp point. A shallow swampy lagoon occurs between these sand spits which are fused together near the eastern extremity. This double sand spit is known as Spencers Spit and it almost connects with Frost Island.

The surface of Lopez Island is relatively flat and free from abrupt changes in elevation. The rocky points that extend out from the north end of the island to form Upright Head and Humphreys Head are in reality islands that are tied to Lopez Island by arms of glacial drift and alluvium. The low wooded peninsula on the west side of Fisherman Bay contains some exposures of the old metamorphic rocks. With these exceptions, the whole northern half of Lopez Island is covered with a deep mantle of glacial materials.

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Matia Islands

Matia is a federal bird refuge. Dozens of species from bitterns and sea parrots to black shags and hummingbirds can be seen at appropriate seasons.

The Matia Islands are located in the Gulf of Georgia about one and one-half miles east of the Sucia Islands. They have a combined area of 170.11 acres, being composed of Matia Island, Puffin Island, and several small rocky islands and reefs.

Matia Island, the chief member of the group, is composed of three elevated parallel ridges and their narrow intervening drift-covered valleys. These ridges are composed of resistant sandstone and conglomerate formations, while the valleys represent the intervening shales and less resistant strata. At all parts of the island the ridges trend about N 68° W.

Matia Island has a length of one mile and a maximum width of 625 yards. At the ends of the island long narrow bays represent the less resistant formations, while the ridges on each side of them extend out to rocky islands and reefs. The greatest elevation occurs at the center of the island, with an altitude of 160 feet. Matia Island is heavily wooded, especially along the drift-covered valleys. The island was used as a fox farm.

A series of reefs extends along the north shore of Matia Island. At the corner of the island there are two small islands, the larger of which is wooded.

Puffin Island is located 350 yards to the east of Matia Island. It rises to an elevation of about 60 feet and its grass-covered slopes are used as a nesting place by many kinds of seafowl. The slopes of Puffin Island are precipitous except on the east. A rocky shelf extends along the north of the island, while to the eastward there are three small reefs that are covered at half tide.

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Orcas Island

Orcas Island, the largest island of the archipelago, has an area of 56.92 square miles. Owing to its rugged topography the arable land on Orcas Island is chiefly limited to the valleys and depressions that are covered with glacial drift. In general the island's shape is that of a trapezoid whose northwest and southeast sides are nearly parallel. The northeast shoreline, which follows the strike of the rock formations, is quite free from harbors or other irregularities. The south side differs from the other three sides in that its shoreline is extremely irregular, being penetrated by three long narrow harbors or sounds.

Orcas Island is cut into two almost equal parts by a narrow and deep depression averaging nearly a mile in width. Except for a distance of one and one-fourth miles at its northern end, this valley is filled with seawater known as East Sound. The depth of water throughout the submerged eight miles of its course is quite constant and it averages around 90 feet.

A second long narrow harbor known as West Sound penetrates the southern shore of the island about three and one-half miles west of East Sound. It is nearly a mile in width and its length is about four miles. At its northern end it is divided into two bays by an elevated spur of land sloping down from Ship Peak, a portion of the Turtleback Range. West Sound trends approximately parallel to East Sound. Its bed is shallow and rocky at its northern end, but its depth increases steadily and uniformly until, at the entrance, it is about 180 feet deep.

A third and much smaller indentation known as Deer Harbor cuts the peninsula to the west of West Sound. It is about one and one-half miles long with its east shore trending parallel to West Sound, while the other trends northeast and causes the harbor to have the shape of a blunt wedge that opens towards the southward. At its northern end, Deer Harbor, after narrowing down to a width of a few feet, opens out into a broad shallow lagoon. A small though deep bay occurs on the west shore of Deer Harbor, and a narrow valley, 50 to 100 yards wide, extends northwesterly from it and crosses to the west shore of Orcas Island.

The eastern lobe of Orcas Island is more rugged than the western portion. Extending up from the lowland that lies to the north of East Sound, there is a rocky dome-shaped mountain known as Buck Mountain, which has an elevation of 1383 feet. To the southeast it is connected with Mount Constitution Range by means of an elevated ridge, the elevation of which is only slightly lower than the top of Buck Mountain. A broad ravine extends towards the southwest and separates Buck Mountain from the western part of Mount Constitution Range. A small lake, known as Buck Lake, is situated on the lowest point along the crest of the divide.

From an elevation of about 1400 feet a rocky spur extends southwestward from Mount Constitution Range and continues towards East Sound. Near the shore of East Sound it rises to a sharp peak known as Mount Rosario, which has an elevation of 860 feet. A portion of this rocky spur projects into East Sound and forms Cascade Bay.

The highest point of land occurring to the east of Mount Constitution Range is here called Mount Pickett, in honor of Captain George Pickett of the United States Army, who served during the San Juan dispute. It has an elevation of 1890 feet and with the exception of the higher peaks occurring on Mount Constitution Range, it is the highest mountain in the area. For the most part, Mount Pickett and the whole Mount Pickett Range are heavily wooded.

The north shoreline of Orcas Island is formed by the steep and rocky slopes of Mount Pickett, Mount Constitution, and Buck Mountain. One or more flat drift-covered benches may be found at elevations of 2130 feet or higher, but otherwise this whole shoreline is steep and precipitous.

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Patos Islands

The Patos Islands are located in the Gulf of Georgia at the extreme northwest corner of the San Juan Island group. The deep waters of Boundary Pass separate them from Canadian islands to the west, which are conspicuous for their strong riptides.

The Patos Islands are composed of Patos Island and Little Patos Island and these have a combined area of 244.5 acres.

Patos Island is about one and one-half miles long and its maximum width is 550 yards. It is elongated parallel to the strike of the rock formation and is curved so that its convex side points towards the south. The west end of the island trends northwest, while the east end of it trends northeast. The strike of the rock formations follows the curvature as well as the elongated direction of Patos Island.

The southern shoreline is rocky and elevations up to 60 feet occur near this side. The north side is low and largely drift-covered but the bedrock outcrops along the shore near sea level.

At the east end of Patos Island there are three long points, composed of resistant material, that extend out far beyond the intervening spaces due to differential erosion. Since these long narrow parallel points of land extend out from the end of the island like the toes on the foot, this end of Patos Island is called Toe Point. The western extremity of Patos Island is called Alden Point, and a lighthouse is located upon it. Patos Island is quite heavily wooded.

Little Patos Island is located near the southwest shore of Patos Island and separated from it by the narrow waters of Active Cove. Little Patos Island is heavily wooded. The whole island is formed from the western extension of the resistant strata that follow along the southern shore of Patos Island. The maximum elevation on Little Patos Island is about 50 feet.

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San Juan Island

San Juan Island is 14.5 miles long and its maximum width is 6.5 miles. It has an area of 55.39 square miles. The shores are usually elevated and rocky except at the southeast portion of the island. The southwest shoreline is broken by only one large bay, known as False Bay, and even here the shoreline is but slightly indented at low tide. False Bay is about a mile long and three-quarters of a mile wide, and it is so shallow that the greater part of the harbor is bare at low tide. At the entrance of False Bay the margins are rocky, but elsewhere they are composed of glacial drift with a low relief. The mud in the bottom of False Bay was derived from glacial clays that occur in the San Juan Valley.

The west side of San Juan Island is cut by four large harbors or bays. From north to south these are Roche Harbor, Westcott Bay, Garrison Bay, and Mitchell Bay.

Indenting the northeast shore of San Juan Island are Rocky Bay and Friday Harbor. Friday Harbor is roughly rectangular in shape and has an average width of one and one-half miles and a length of more than a mile. It opens towards the northeast. Near the entrance of Friday Harbor the water is more than 300 feet deep. Friday Harbor apparently owes its origin to the presence of two or more intersecting fault or fracture zones occurring in the underlying rock formations.

Griffin Bay, the largest bay occurring on San Juan Island, is located on the east side of the island between Cattle Point and Pear Point. It is somewhat rectangular in shape, with a width of nearly four miles and a length of approximately two miles. The water near the shore is shallow in some places, while in others the deep water extends close to the shoreline. Within half a mile from the shore there are numerous small scattered reefs and rocks, many of which do not rise high enough to be uncovered at low tide. Beyond a distance of half a mile from the shore the water increases rapidly in depth and reaches a maximum near the center of the bay with a depth of about 275 feet.

Davidson Head, the most northern point on San Juan Island, is a rocky wooded peninsula with an area of 48 acres. It is connected with the mainland by means of a narrow sand spit. Davidson Head is elongated in an east and west direction which is parallel to the strike of the rock formations.

Extending along the northeast shore of San Juan Island to the north of Sportsmans Lake, there is a range of hills with a maximum elevation of 520 feet. Farther to the southeast there is another hill with an elevation of 380 feet, which is separated from the others by the depression that contains the stream issuing from Sportsmans Lake. These hills are all heavily wooded on their northern slopes, while the southern slopes are either bare or covered by a few scattered conifers.

The lack of conifers on the southern slopes is noticeable on all of the islands where the soil is shallow or sandy. This phenomenon has been ascribed partly to the relative conservation of moisture on the northern or shady side, and partly to the fact that the most prevalent wind storms come from the south and uproot the vegetation on the southern slopes, especially when the soil is sandy.

While the shoreline is usually bounded by elevated rocky hills, the typical topography of the central part of San Juan Island, with its numerous drift-covered valleys and depressions, has furnished this island with an abundance of fertile land.

There are no continuous streams on San Juan Island. During the rainy season a small stream follows the bottom of the San Juan Valley and into False Pay.

A small intermittent stream that flows eastward and empties into San Juan Channel drains Sportsmans Lake, the largest lake on the island.

The village of Friday Harbor is supplied with water derived from Trout Lake nearly five miles away. Trout Lake has no outlet that reaches the sea.

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Shaw Island

Shaw Island, because it is located at the geometric center of the San Juan Archipelago, is sometimes called "the Hub." The Wilkes expedition named it for John D. Shaw, who served prominently in the Algerian war of 1816. It is the smallest of the bigger islands in the group.

Today agriculture and fishing are the mainstays as they are on Lopez, but in the past Shaw has had a somewhat more diversified economy. Moderate limestone deposits were being quarried on Shaw in the late years of the 19th century. When the quarries shut down later on, many Shaw Islanders turned to cutting cord wood for the Roche Harbor Lime Works.

Shaw Island is located in the center of the San Juan Island group. It is separated from San Juan Island on the southwest by San Juan Channel. On the southeast Upright Channel separates it from Lopez Island. Harney Channel separates it from Orcas Island on the north, while on the northwest it is separated from the Wasp group of islands by Wasp Passage.

Shaw Island has an area of 7.71 square miles. It is roughly triangular in shape and its shorelines are generally low and rocky, being cut by numerous harbors and bays.

A large shallow bay known as Blind Bay penetrates the north shore of Shaw Island. It is about a mile long and three-quarters of a mile wide. It is a part of a broad depression of glacial origin that crosses Shaw Island in a north and south direction. At the south side of the island this broad valley is given its physiographic expression by the formation of the shallow bay known as Indian Cove.

Numerous irregular harbors and bays break the southern shores of the island.

The greater part of the surface of Shaw Island is covered with rocky elevated knobs and intervening drift-covered valleys. It is probable that the latter generally follow fracture or fault zones. Largely the drift-covered valleys that are at, or a little below, sea level cause the irregularities in the shorelines.

The most elevated knobs occur in the west central portion of the island where elevations up to 300 feet may be found. Deciduous trees predominate in the valleys, while conifers are abundant in the higher areas. Shaw Island is more heavily wooded than any of the other islands of the San Juan Island group.

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Skipjack Island

Skipjack Island, with an area of 19.28 acres, is located about a mile to the west or slightly northwest of Bare Island. In contrast with Bare Island it is wooded and rises to an elevation of 120 feet.

Skipjack Island is elongated in an east and west direction. Its parallel sides trend to the strike of the rock formations, the dip of which is steep or nearly vertical. Due to the differential erosion of the shale strata, narrow bays with parallel sides penetrate the ends of the island. The widths of these bays are determined by the thickness of the eroded strata. For the same reason two longitudinal valleys cross the island and these are partly covered with glacial drift.

About 200 yards to the east of Skipjack Island there is a small reef which is awash at high tide.

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Spieden Island

Spieden Island is situated about a mile from the north shore of San Juan Island, being separated from it by the deep waters of Spieden Channel. It has an area of 480.45 acres.

Spieden Island is nearly three miles long and its maximum width is only 875 yards. It trends about N 70° W, or roughly parallel to the strike of the rock formations. Near the central part of the island the elevation reaches a maximum of 410 feet. The east end of Spieden Island is less elevated than the western portion. The eastern extremity is formed by a dome-shaped hill rising 80 feet above sea level, known as Green Point. To the west of the dome-shaped hill a broad lowland crosses the island at an elevation of about 25 feet. Still farther westward the land rises to a maximum elevation of 410 feet.

Beginning to the west of the lowland, a drift-covered shelf extends along the north side of Spieden Island for a distance of one and one-half miles. This shelf has an average elevation of about 40 feet at the water's edge, and rises at a gentle angle. At a distance of about 250 yards from the shore near the central part of the shelf, and at a shorter distance when measured from a point to the east or west of the center, the elevations increase towards the top of the ridge. The north side of this elevated ridge, though somewhat precipitous, is heavily wooded, while the southern slopes are devoid of trees.

Sheer cliffs that rise to a height of 260 feet bound the western part of the north side of Spieden Island. The western extremity of the island is known as Spieden Bluff.

Spieden Island is surrounded on all sides by deep water near the shore and it has the distinction of being the only large island of the San Juan Island group that does not possess a harbor.

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Stuart Island

Stuart Island is the most western of the San Juan Island group, being located in Haro Strait to the northwest of San Juan Island. It has an area of 2.79 square miles.

Due to the fact that Stuart Island is composed of closely folded sedimentary rocks that have suffered from differential erosion, the shoreline is exceedingly irregular. In certain cases the softer formations have been eroded to such an extent that they are now covered with water, and long narrow bays with parallel sides result. Were it not for the presence of two large harbors Stuart Island would be roughly elliptical in shape with its major axis about N 65° W.

A long narrow embankment known as Reid Harbor enters the island near its southeast extremity. With an average width of 500 yards and an average depth of 25 feet at low tide, it trends northwest for a distance of nearly two miles. Reid Harbor is located on the axis of an elongated centroclinal fold in the underlying rock formations. To the northwest of Reid Harbor the same erosional and structural valley extends as far as the western shoreline of the island, being flanked on each side by an elevated and consequently more resistant rock formation. On the south side of the valley this resistant formation rises in the form of an elongated dome called Tiptop Mountain, which is 640 feet high. On the north side of the valley these same resistant strata again appear, and they serve as the narrow arm which separates Reid Harbor from Prevost Harbor.

To the north of this central resistant rock ridge there is another softer formation which is represented by a valley of low relief. Still farther northward the same resistant strata appear for the third time, and they form the elevated northern margins of Stuart and Satellite Islands. Along the northern side of Stuart Island this resistant formation is broken through in two places about a mile apart, and the water entering the valley to the southward connects the one inlet with the other and forms the large harbor known as Prevost Harbor. The elevated landmass occurring in and surrounded by the waters of Prevost Harbor is called Satellite Island.

The central elevated ridge has a maximum elevation of 420 feet, while the northern ridge attains an altitude of 500 feet. The shorelines along the north and west sides of Stuart Island are steep and rugged. At the northwest extremity of Stuart Island is a precipitous rocky point called Turn Point, on which a lighthouse is located. Strong riptides characterize the nearby waters of Haro Strait.

A rocky area that is connected with the remainder of the island by an uplifted arm of alluvial materials forms the northeast extremity of Stuart Island. Stuart Island is only moderately wooded.

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Sucia Islands

The Sucia Islands have an abundant source of sandstone and are located in the Gulf of Georgia about three miles to the north of Orcas Island. They have a combined area of 749.0 acres.

The Sucia Islands owe their origin to the differential erosion of stratified rocks that have been folded into the form of a trough or syncline that is inclined towards the east. During the lapse of time since the folding of these the region has been reduced by erosion to an approximate level, and due to the inclined trough-like structure of the rocks, the outcrop of each stratum has the general form of a horseshoe. By the processes of erosion, the shale strata have been eroded somewhat deeper than the more resistant sandstone and conglomerate layers that stand out to form parallel horseshoe shaped ridges. In some cases the softer formations composing the Sucia Islands are represented by drift-covered valleys, while in others they are covered by seawater to form long narrow bays or channels.

The Sucia Island group includes the following islands: Sucia Island, Little Sucia Island, Herndon Island, the South Finger Islands, North Finger Island, Ewing Island, Clements Reef, and a number of other small rocks and reefs.

Sucia Island, which forms the nucleus of the Sucia Island group, is composed of portions of five parallel horseshoe-shaped strata, two of which are soft while the remaining three are relatively resistant. With the exception of the south side, the island is composed of two parallel resistant strata with an intervening softer stratum.

Near the western extremity of the island, the outer ridge of resistant material is broken through, so that water enters a portion of the shallow valley representing the softer stratum. The result is a bay called Shallow Bay. The shallow waters of Echo Bay occupy the central portion of the horseshoe.

Steep cliffs that slope abruptly down bound the north arm of Sucia Island into deep water. This elevated region is known as Lawson Bluff and rises to a maximum height of 160 feet. A narrow channel that separates Ewing Island from Sucia Island crosses the outer ridge belonging to the north arm of Sucia Island. In this region the inner ridge is represented by a series of small rock islands, while the intervening softer stratum is covered with marine water.

The inner member of the south arm of Sucia Island extends out towards the east without any break in the ridge. The extremity of this ridge is called Johnson Point. The valley to the south is largely filled with seawater, and the next ridge to the south is broken through in two places. The intervening portion of this ridge forms Herndon Island. To the south of this ridge the water enters from the east along an erosional valley to form Fossil Bay. The head of Fossil Bay is separated from Fox Cove, another bay entering the island from the westward, by a narrow neck of land.

The rock formations on the south side of Fossil Bay are richly fossiliferous. These rock formations extend westward to form Little Sucia Island.

The surface of Sucia Island, and particularly that of the drift-covered valleys, is covered with a dense growth of vegetation. Sucia Island was used as a fox farm and is currently a state park.

Little Sucia Island is located just southwest of Sucia Island. It is an extension of the fossiliferous strata that forms the southern margin of Sucia Island. The shores of Little Sucia Island, as well as the exposed shores of the other islands of the group, are fringed by flat rocky shelves that have been formed by wave action at high tide. The island is crossed by a depression that is filled with glacial drift and alluvial material.

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Waldron Island

Aside from rum-running and Indian missions, the leading industries on Waldron were fishing, farming, some logging, and stone quarrying. Waldron and one or two other islands have large quantities of excellent grades of sandstone, used for paving city streets around the turn of the 19th century.

Life seems to move more slowly on Waldron than almost anywhere else. Clocks are little esteemed. There is no public electricity, no telephone, no community water. Waldronites – many of them descendants of the men and women who make up the island's history – mostly prefer to do without modern conveniences. There are a few cars on the island, and "about as many cars as there are dogs." The roads are narrow, unpaved, and overhung with brush and trees.

Waldron Island has an area of 4.59 square miles. It is located about one and one-half miles from the northwest shore of Orcas Island and separated from it by the deep waters of President Channel.

The southeast portion of Waldron Island is elevated and rocky, but elsewhere the island is deeply covered with glacial drift and elevations above 100 feet are rare.

The highest portion of the island is roughly elliptical in shape, with its longer axis trending about N 45° E. Although this area is surrounded on all sides by steep slopes, the structure of the underlying rock formations is just the reverse of the topography, since this is at the same location of an elongated centroclinal fold. The maximum elevation of this is 580 feet.

The southwest end of the elevated region projects out into the water about a mile beyond the adjoining shores to form Point Disney. The cliffs on the northwest side of Point Disney rise vertically from the waters to a height of nearly 500 feet.

The elevated portion of Waldron Island is covered with an abundant growth of oak trees and conifers that have favored the soil derived from the weathering of certain shaly sandstones. As a consequence the trees now occur in curved rows which follow the outcrops of these formations.

A small double rock-bound bay occurs on the east side of Waldron Island near the northern extremity of the elevated area, known as Mail Bay.

To the north of the rock point which forms the northern margin of Mail Bay the region is low and covered with glacial drift. Near Point Hammond at the northeast corner of the island, the stratified cliffs of glacial materials rise to an elevation of 100 feet, while the bedrock outcrops near the water's edge. Several rock points outcrop along the north shore of the inland beneath the cliffs of glacial materials. One of these rock points extends out from the northwest comer of the island to form Fishery Point.

The central part of the west side of Waldron Island projects to westward as a long narrow point of glacial drift and alluvial materials which have a low relief. This long point is called Sandy Point. Between Sandy Point and Point Disney there is a broad embayment known as Cowlitz Bay. Waldron post office and boat-landing are located on the shore of this bay.

Near the southeast side of Cowlitz Bay there is a reef, known as Mouatt Reef, which rises about three feet above low tide.

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References Cited

1. Environmental Protection Agency (EPA). Surf Your Watershed: San Juan Islands. <http://cfpub.epa.gov/surf/huc.cfm?huc_code=17110003>

2. McLellean, Roy. 1927. The Geology of the San Juan Islands. University of Washington Press. Seattle, WA.