Reading Summaries

The Natural History of Point Reyes: Chapter One Summary

Prologue:
The prologue introduces what the author wants to talk about for the book. It starts by interpreting a quote about the Point Reyes peninsula, and moves on to incorporate the history of the region, and some of its special characteristics. It highlights the importance of understanding the history of a place to understand it in the present.

Chapter One:
The author starts by introducing the characteristic wind and fog of the Point Reyes Peninsula. He breaks the weather patterns into seasons. The Coastal Miwok who naturally inhabited this area broke the year into 13 seasons according to what food was available at the time. The author argues that it would be perfectly reasonable to break the year into two seasons, the wet season and the dry season, but for the purposes of this book he wishes to break the weather into the four seasons in order for reader comprehension.

Maritime Influences
The north Pacific High is a mass of air that sits 1000 miles off the California coast at about that latitude of Point Reyes. This mass of air moves north and south seasonally, and directly affects the local weather pattern. As winter approaches this pressure system moves northward to 38N. Its movement north creates the spring winds, but once the pressure system is in place it creates a block for storms headed for the coast. As winter progresses the system moves south again exposing the coast the later winter storms. Three major movements of water along the coast are the Upwelling Period occurring in spring and summer, the Oceanic Period that occurs in September and October, and the Davidson Countercurrent that predominately happens in the winter.

Winter: The Rainy Season
The Point Reyes Peninsula has a short winter and a long dry summer, this is known as a Mediterranean climate. However, the wind and fog of Point Reyes moderate this pattern. The timing rainy period is fairly reliable, usually starting in November, and ending in March, but there is a vast variation in the annual amount of rainfall. Sometimes the Pacific High stays in place, creating a drought year, but this is fairly rare. In February the flowers begin to bloom, and the days begin to lengthen.

Spring: The Windy Season
As winter dissipates the Pacific High once again moves northward to protect the coast. Low-pressure systems tend to develop in the central valley causing average daily winds of 35mph, and peak winds of 80mph along the Point Reyes Peninsula. These winds combined with the Coriolis Effect cause the costal upwelling that brings cold nutrient rich water to the surface. Spring is generally one of the longer seasons, sometimes starting as early as January.

Summer: The Foggy Season
Winds saturated with water vapor from the warmer offshore water are driven onshore, across the cold costal water. As the water cools the air it reaches “dewpoint” and becomes fog. Fog is defined as “condensed atmospheric water in sufficient concentration to reduce visibility by 3,280 feet.” The visibility on a foggy summer day is often reduced to 150 feet at the lighthouse. When the water temperature is not cold enough to instantly make fog the cold air rises to meet the hills and turn into gray overcast. Fog movement through the trees on the point, and along the Inverness ridge provide around 12 inches of fog drip during the summer, providing them with water that they might not otherwise get until winter.

Fall: The Subtropical Season
By mid August the fog begins to lessen and the browned hills are visible. Costal temperatures raise, and it can even get up to 80 degrees at the lighthouse. Most wildflowers and perennial plants die leaving only the green of the evergreen trees. In the tidal flats of Drakes Estero, Tomales Bay, and Drakes Bay, ducks and arctic seabirds have begun to arrive. In late October winter begins to show itself in the turning leaves of willows and alders along the creeks. Gray Whales are often sighted from the lighthouse in late fall.

Anomalous Patterns.
The Point Reyes Peninsula has a relatively reliable weather pattern, but anomalous weather patterns sometimes can help to disrupt it. Floods are often associated with an “El Niño” year. El Niño often occurs once a decade every 3-10 years, but is not well understood by scientists. It is a warm countercurrent that results in southeasterly trade winds, warmer waters, and the migration of new species. In the El Niño year of 1983, Barracuda, Roughtoothed Dolphin, and Striped Dolphin were all found in The Gulf of the Farralones, these are all species that are usually found much farther south. Drought is another irregularity that is not well understood, although it is known that it is the result of air masses, ocean currents, and water temperatures. Luckily droughts are almost always proceeded by flood years.

Chapter Two Summary:

Geology:
The author begins by comparing the Point Reyes Peninsula to a gray whale, and pointing out several similar attributes. The geology of the peninsula is as old as 225 million years, although the exact age can only be guessed. The peninsula is constantly creeping northwest at as much as 2.15 inches per year. Occasionally there is a major shift in the fault such as the 1906 earthquake when the peninsula jumped 13 feet. The granite outcrops of Inverness Ridge have replaced metamorphic rocks of the peninsula.

The San Andreas Province:
The San Andreas Fault separates Point Reyes from the North American Plate. The Peninsula has similar vegetation to that of the North American Plate, but geologically it is very separate. Most of the rocks found west of the San Andreas fault are from the Tertiary period. The Granite on the Inverness Ridge is slightly older dating back around 136 million years. The Peninsula as a whole can be broken down into three geologic regions, the granite Inverness Ridge, The Point Reyes Headlands, a granite body overlaid in conglomerate, and the area in between, and basin of sediments.

Metamorphic Rocks:
Metamorphic rocks including schist, quartzite, and limestone are the oldest rocks of The Peninsula. They occur mostly along the Inverness Ridge although lots of them are embedded in granite. The metamorphic rocks found on The Peninsula are also found in Santa Cruz, Santa Lucia, and Gabilan.

Granitic Bedrock:
The piece of granite bedrock that the Inverness Ridge is part of stretches east, and also south all the way to southern California. It is thought that the granite is older than the Franciscan formation that it borders. The top of the Inverness Ridge reaches 1300 feet above sea level.

Tertiary Rocks:
The Point Reyes Conglomerate dates back about 65 million years and the maximum thickness of the layer is about 700 feet. The conglomerate is mostly made up of granite rocks embedded in granite sand along with chert.

Miocene Rocks:
Laird Sandstone, a younger coarse-grained rock, overlies the western side of the Inverness Ridge. Monterey Shale overlays some parts of the granite base. The shale is made up of cherts, sandstones, and organic shales containing many single celled organisms.

Pliocene Rocks:
The basin between the Inverness Ridge and the Point Reyes Headlands is filled with marine sediment that is as young as 8 million years. Greensand makes up the Drakes Bay formation and is a fossil rich medium.

Soils:
The Soils of the Peninsula are also different from that of the mainland east of Tomales Bay. The soil types reflect the geologic patterns of the area.


Chapter 3: Plant Communities

Bishop Pine Forest:
Although bishop pines were once common now they only occur in the humid coastal range of California from Humboldt to Santa Barbara. On the Point Reyes Peninsula bishop pines are restricted to the north end of the Inverness Ridge, they almost all occur in soils of granitic origin. Other trees are sometimes mixed in with the pines but are usually secondary members of the community. Bishop pines are a type of close-coned pine. This means that they are dependent on fire for reproduction.

Douglas Fir Forest:
Douglas Fir is the primary tree on the southern end of the Inverness Ridge. The firs survive in Monterey shale, and get about 30 to 42 inches of rain per year. Although many of the trees were logged in the late 1950s, many original growth trees still stand in the more isolated areas. Some Douglas Firs rival redwoods in height and size.

Coastal Strand:
What is known as the coastal strand is the strip of land directly along the ocean. Much of the coastal strand is made up of sand dunes and dominated by invasive beach grasses and ice plant. The strand is broken up into three subhabitats: the foredune, the central dune, and the hinddune. The largest dune system on the peninsula borders the great beach. Most of the plants find refuge in the hinddune.

Coastal Rangeland:
Treeless rolling pastures dominate the western and northern sections of the peninsula. Most of this land is designated for agriculture. The areas left ungrazed are mostly covered by perennials. Many of the grassland wildflowers are hard to see and covered by grass most of the year; however, in winter and spring there is an abundant native bloom. These grass lands also are home to the Swamp Harebell, a rare plant that only occurs along the coast in shady canyons.

Northern Coastal Scrub:
The northern coastal scrub is a narrow strip that extends from Southern Oregon to Monterey County. This strip is predominately coyote bush and bush lupine which both have extensive communities on the Inverness Ridge. In the drier areas California Sagebrush is found with the coyote bush. On the coastal slope of the Inverness Ridge, Pink Flowering Currants bloom starting as early as February. One of the more rare California grasses, called California Bottlebrush-grass, also is part of this habitat.

Marshlands:
The marshlands on the Point Reyes Peninsula have been mostly destroyed by agriculture. The marshlands that remain can be broken into two categories: salt marshlands and freshwater marshlands. There are about 1,000 acres of salt marshland on the peninsula. The vegetation in the salt marshes is almost identical to that of San Fransisco Bay marshes. Freshwater marshes are scarce on the peninsula. These marshes are mostly covered by Rushes, and the Marsh Monkeyflower.

Intertidal Plant Communities:
Almost all marine plants are algae, which lack true flowers, leaves, or roots. There are three existing types of marine algae: green, brown, and red. The color used to classify each plant is not necessarily recognizable to the human eye. The only marine plants that have adapted to the ocean enough to flower are eelgrass and surfgrass, which both occur in Point Reyes. Extensive kelp beds border sculpted beach and play host to short kelp, stalked kelp, bull kelp, and California kelp.



Chapter 4: From the Ocean's Edge to the Serpent's Lair

Marine Invertabrites:
The tide pools and other subtidal areas of the peninsula house an amazing amount of marine life. This habitat can only be viewed on a serious minus tide. The distribution of invertebrates depends mostly on the temperature of the water. The cold to warm water transition in California occurs south of Point Reyes at Point Contraception. The subtidal habitat of Pont Reyes can be divided into three zones, sany beaches, rocky shores, and bays or estuaries.

Eelgrass Beds:
Eelgrass beds serve as an excellent habitat for many marine species. Eelgrass is widely known as the only flowering underwater plant. The eelgrass beds promote the growth of algae, diatoms, and bryzoans. These are eaten by seaslugs and snails.

Fishes:
There are three main events that happen annually. These include the migration of the salmon upstream, the migration of gray whales past the headlands, as well as the herring run in Tomales Bay. Herring group in large school in early winter and migrate inshore to spawn in estuaries and bays. The fish lay there eggs on the vegtation, namely eelgrass in tomales bay, because it makes up 75% of the underwater vegetation. Silver salmon were also once abundant in this area. Sadly they have been overfished throughout the years, and the creeks that they spawn in have habitat issues.

Amphibians:
There are six types of salamanders native to the Point Reyes Peninsula. As it rains these salamanders make it to the nearest puddle or stream to mate. Later on in the winter when the rains have saturated the ground frogs can be heard in many ponds and marshes. The peninsula is home to the red-legged frog, a nationally endangered amphibian.

Reptiles:
The only turtle that occurs on the peninsula is the western pond turtle. However lizrds and snakes are abundant. There are four species of lizard on the peninsula most abundant are the Alligator Lizard, and the Western Fence Lizard. There are several species of snakes that live on the peninsula also, including the Western Rattlesnake.


Chapter 5: Birds the Sky People

Shorebirds:
Winter provides the largest amount of food for birds. A variety of different birds feed in the park within the winter, some all the way from Alaska or Canada, and some residents of a park. Different bodies of water in the park provide 18 square miles of estuarine habitat; there are also 25 miles of sandy beaches. Abbott’s Lagoon, being the only estuary not affected by the tide plays host to multitudes of birds whenever the tide is high.

Seabirds:
Seabirds can survive a variety of habitats. Seabirds feed mostly on fish and follow their migrations. Many birds follow the herring into Tomales and consume 56-99% of the spawn that they produce. Thousands of birds gather on the water and can be seen in Drakes Bay, Tomales Bay, Drakes Estero, and many other places.

Raptors:
Winter is also the best season to see raptors, or birds of prey. The most common are red-tailed hawks and American Kestrels. The number of raptors varies greatly year to year due to global weather patterns and the abundance of food. When there is a mild winter the birds may choose to stay farther north in the Pacific Northwest or the Great Basin. Other times an abundance of prey prompts a population explosion of raptors.

Landbirds:
In late September and early October the landbirds make their way to the Point Reyes peninsula. Some species remain year round to breed here are some migrate for the winter months. The number of berries that can be scavenged during the winter months attracts many of the birds. Some wintering species return some years and not others.

Pelicans:
Brown Pelicans winter in Point Reyes, usually arriving from Baja in May or June and staying through December. The migration is due to the changes in fish populations in different regions though out the year. The pelicans later breed in the Gulf of California often off the Channel Islands. The White Pelican also winters in Point Reyes. It is extremely rare for the two species to co-exist and Point Reyes is on of the only places where this is seen. In Point Reyes the Brown Pelican arrives earlier in the season and in more abundance. Historically both species of pelican are on the decline. Many died off as a result of the chemical DDT. Populations are beginning to rise but white pelicans remain rare.


Chapter 7 Summary: Marine Mammals

Marine Mammals
The area that extends from Tomales Point out into the Gulf of the Farallones has a rich variety of marine life. A combination of upwelling and shallow water attracts herds of whales and pinnapeds. Before whaling and hunting stations were set up there must have been multitudes of marine mammals in this area. Sadly marine mammals suffered greatly in the 19th century, but recently numbers have been in the rise particularly in the elephant seal and blue whale populations.

Sea Otter
Sea otters once bred at Point Reyes, out on the Farallon Islands, and in other near shore locations in California, Otter pelts were greatly sought after in the 18th century and they were hunted nearly to extinction. By the early 1900s sea otters were displaced from the entire California coast. Later a small population was discovered south of Monterey and since the species has been under protection. Recently the population has been on a rise although they are still considered an endangered species in California. Otters have a relationship with kelp beds and since the decline in the otter population kelp beds in California have also been dwindling.

Pinnapeds: Seals and Sea Lions
Over 2500 harbor seals have been counted around Point Reyes making it the most abundant stretch of California coast. Harbor seals tend to be shy of people,which helps them survive in close proximity to civilization. Harbor seal hall-outs are scattered around the Point Reyes Peninsula, and contribute to 25% of pups born in California. Seals tend to forage for food at high tides and at night, using the middle part of the day and lower tides to haul-out and rest. Harbor seals are small (generally 150 to 200 pounds) and walk awkwardly on land.

Northern Elephant Seal
Elephant seals are considered one of the most fascinating animals in the park for several reasons. Like sea otters elephant seals were once hunted as a natural resource. This time it was for the use as their blubber. In 1868 elephant seals were though to be extinct but by 1892 a small population was found on an island of the coast of Baja. Since the elephant seal populations have been protected and they have become increasingly prolific. Animal size differs greatly in the males and females. Point Reyes is the northern most breeding site for the elephant seal and many of the beaches and coves around the point host breeding colonies for the seals.

California Sea Lion
California Sea Lions can be seen from the sea lion overlook near the lighthouse or swimming in Drakes Bay. Although the sea lions venture as far north as British Columbia the Farallon Islands are the northern most established breeding colony. Sea Lion Populations have been on a general rise in the last 50 years including a rise of three-fold in the population in four years.


Northern Sea Lion
Northern sea lions have a shortly lighter coat and shorter nose than their relative the California seal lion. In contrast to the change in population of the California sea lion the northern sea lion population has slowly decreased over the last 50 years. Northern sea lions can often be seen halled-out at the headlands.

Northern Fur Seal
Between 1810 and 1812 70,000 fur seals were hunted from the Gulf of the Farallones. Sightings are rare and are usually adult females or juveniles. There have been sightings along the Cordell Bank and as far north as Alaska.